Author Archives: Maximus Chillers

Blue recovery unit with a grey recovery cylinder during a chiller breakdown

Chiller Breakdown

A rainy day for a chiller breakdown for our engineer in the North West.

News Article No.8

Electrical Faults during Chiller Breakdown

Our customer called us out because he was having electrical faults with the chiller. The power supply to part of the panel had gone down and he required our assistance. Our engineer found a blown fuse which he replaced and tested operation- it blew again. Using his multimeter, he followed the diagnosis though to an earth fault on the flow switch…

Water System Flow Switches

The flow switch vapour seal had failed allowing rain water to ingress. This caused an earth failure on the 240v control circuit, and so blowing the fuse. The customer raised an order forthwith and so our engineer replaced the flow switch with the stock from his car. Each of our engineers keeps a range of flow switches for a variety of applications…

Stainless Steel

Where water system chemicals are corrosive, we carry corrosion resistant flow switches. This type has a longer working life due to the use of stainless steel. They are more expensive due to the higher manufacturing costs, but they are worth the money as they are less likely to fail, causing a potential loss of production.

Outside Use

This was the type fitted by our engineer on site in this news article. It has been developed and tested across a range of adverse weather conditions including freezing conditions and heavy rain. The electrical and switching compartment is protected by a sealing gland to keep the weather out. A rubber ‘o’ ring provides the seal into this compartment.

Inside Use

Some applications have the flow switch located inside the building in the plant room with the control cable extending out to the chiller controls. Another configuration allows for the flow switch to trip out the building controls and so dropping out the run signal to the chiller. In either case there is no need for weather proofing. This kind of flow switch is cheaper due to the lower construction costs.

High Pressure

Some water systems operate at considerable pressure. Therefore, high pressure flow switches have been developed for this application. They are capable of preventing water ingressing from the water system and into the electrical and switching compartment.

Test and Adjustment

Our engineer carried out testing and adjustments to the flow switch to ensure that it ran reliably. He achieved this by monitoring the water system readings and measurements against the design specifications of the switch. When he got it to settle down, he replaced the fuse and ran tested the chiller...

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Condenser Fans

The condenser fans were not coming on at all at first and later only slowly. They are controlled by a fan speed controller which is sensitive to pressure. A minimum value of volts is supplied to the fans, so as to prevent stalling and over heating of the internal motor windings. The fans were found to be in good working order, so he decided to turn his attention to…

Refrigerant Pressure Temperature Relationship

There was found to be a lower pressure and so a lower temperature in the condenser. After careful fault finding and diagnosis involving putting the pressures and temperatures into a calculator, our engineer decided that the chiller was running short of refrigerant. This is consistent with Charles’s Law of Constant Volume: one of the fundamental scientific principals of how a chiller works- the higher the pressure- the higher the temperature/ the lower the temperature- the lower the pressure.

Refrigerant Recovery Units

After receiving a further order from our customer, we gave the go ahead to our engineer to use his refrigerant recovery unit to decant the gas. The refrigerant is sucked into the unit using a small one cylinder reciprocating compressor. The compressor discharges into the on board condenser which is cooled by a fan. The subcooled refrigerant travels down a refrigerant hose which is connected to the recovery cylinder in the picture. After this process was complete, he started looking for a leak...

Leak Testing and Pressure Testing

The leak was identified on the flange for the expansion valve. This component was removed, cleaned with our in house refrigerant grade solvent, then the joint re made with a compound suitable for the temperature range of the component. After a satisfactory nitrogen pressure test, the evacuation process can begin…

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Refrigerant System Vacuum Pumps

Each of our engineers carry a high capacity vacuum pump of the highest quality. We believe in investing in state of the art equipment as this is part of how we provide the MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere. Good equipment makes the job go easy.

Vane Pump

The pump works by sucking vapour into the inlet port. A rotary vane system extracts the vapour and discharges it through the top of the pump module. Oil is used to lubricate the vanes that slide around the pump cylinder. The vanes are kept a tight fit against the cylinder with the use of springs. As our pumps are high capacity, an oil filter is fitted to the outlet with a gauze inside to catch any oil droplets.

Electric Motor

This motor fits onto the back of the vane pump module. It comes from the factory set to 240v, but we change the pins for the electrical connections to convert it for use with 110v. This is because customers and engineers demand the use of 110v as if is safer for use in the UK climate. The 110v plugs and extension cable are shrouded and weather resistant. Weather resistant does not mean weatherproof, so we take measures to limit the exposure to adverse weather conditions. The pump motor, however, is not weather resistant at all, so care is taken to locate it somewhere dry. After a long time running, the motor runs hot, so our engineers take readings and carry out adjustments to ensure that it stays within its nominal operating temperature range.

Oil Changes during Chiller Breakdown

The vac pump oil is changed before each use with our specialist grade, high quality oil. Contact our office for prices and delivery times. The manufacturer of the pump recommends these oil changes as moisture and impurities absorb into the oil and so reduce its performance, also the working like of the pump.

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Refrigerant System Evacuation Process

Having set up the vacuum pump, our engineer started the evacuation process.

Torr Gauges used During Chiller Breakdown

We use analogue Torr gauges as they are more reliable than digital ones. Also, they do not need batteries and it does not matter if they get wet. He attached the Torr gauge to a suitable part of the system with a refrigerant hose, ensuring that a good seal was made between the components with a sealing compound.

Fittings used during Chiller Breakdown

Fittings were used to get between the different thread types from the vac pump to the fridge system. Having warmed up the pump for half an hour he was ready to start the process.

Non Condensables Removed during Chiller Breakdown

One purpose of evacuation is to remove the gasses that will not condense such as nitrogen remaining in the system from pressure testing. Another non condensable is air that has entered the system from when the expansion valve was removed. These non condensables affect how a fridge system works according to Dalton’s Law of Partial Pressures: that all gasses in a vessel act as if they are on their own. The non condensables cause a higher head pressure and false readings: when this pressure is added into our calculation- it throws out the sum and so gives a false reading of subcooling.

Dehydration during Chiller Breakdown

The other purpose of evacuation is to dehydrate the system. Water, as we know, has a boiling point of 100°c at sea level, which is 1bar absolute or 760 Torr. As you start to drop the pressure, so correspondingly, the boiling point also drops. For example, water boils at the top of Mount Everest at around 68°c. If we continue vacuuming a refrigerant system, eventually we can remove all moisture by dropping the pressure below the saturation point of water. This works even in the winter in UK ambient conditions. Moisture in the system causes system failures and malfunctions leading to expensive breakdowns.

To read more about flow switches hit the Tag at the top of the page.

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Read more about rotary vane pumps at Wikipedia | Click Here


Chilling plant maintenance of grey machines with red warning signs

Chilling Plant Maintenance

We at Maximus Chillers carry out chilling plant maintenance in factories and facilities around the UK and overseas.

HFC Refrigerants

HFC (hydrofluorocarbon) chiller refrigerants were developed to be chlorine free. For a while they were seen to be the great new thing until the GWP (global warming potential) of the refrigerants became more of a concern. The release of these refrigerants from leaking systems dramatically increases the green house effect and so trapping more heat in the atmosphere. For this reason, F-gas regulations are phasing them down to 21% by 2030. Because of the 650kg charge in the chillers in the photo, we carry out leak testing at one month intervals. Where a leak is identified with this refrigerant, the system can be pumped out using the push/ pull method. There are no refrigerant system shut off valves available to allow the systems to be pumped down.

Chilling Plant Maintenance using Leak Detectors

We employ HFC refrigerant leak detectors to identify any leaks around the system. On systems of this size, there may be more than one leak, with a large leak alerting the attention of the engineer and the smaller leaks found subsequently. Our leak detectors are sent off periodically to be calibrated with the internal replaceable components upgraded as necessary.

Static Leak Detectors

Static leak detectors are available for each machine to catch any leaks as soon as they happen- before the one month intervals. This reduces the amount of refrigerant leaking to atmosphere and so adding to global warming. These leak detectors are bump tested on each visit to ensure reliability with replacements available on site, should one of them fail.

Chilling Plant Maintenance for One World

The above measures are essential with this kind of refrigerant in the interests of the environment. Basic checks now, protect the future of the planet. We only have one world, so we need to look after it as best we can. You can rest assured that you are in safe hands with how we handle this range of refrigerants.

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Shell and Tube Chiller Condensers

During the maintenance, we assess the subcooling values under part and full load to diagnose the efficiency of the shell and tube condensers. This kind of condenser is very popular with larger chillers in the UK. They are not sensitive to different weather conditions as the heat rejected into the condenser water system is pumped into the cooling towers outside of the plant room.

Chilling Plant Maintenance of Copper Pipework

The nest of pipes inside the shell are constructed using copper. This is because of the excellent heat transferring properties of this metal. On other sites where the refrigerant is ammonia for example, stainless steel is used as ammonia corrodes copper and most other metals and alloys. Thorough maintenance of the pipework is carried out on each visit.

Water System Maintenance

The water loop is inspected at various test points around the system with our range of test equipment. Where there are readings that are starting to go beyond nominal conditions, we carry out adjustment to bring them back into line. If the water system is behaving abnormally, this will in turn affect the efficiency of the condenser. In extreme circumstances, a system failure can occur causing a potential loss of production. Effective maintenance from Maximus Chillers has evolved over time to prevent this from happening in the first place. Each time we encounter a new issue, a thorough investigative process is carried out, the solution is arrived at and this is added into the routine.

Air Bleed Ports during Chilling Plant Maintenance

Air can be pulled into the condenser from the cooling towers outside. This can sit on top of the water in the condenser and so prevent the heat exchange of latent heat from the refrigerant and into the water. An air lock in the condenser amounts to that portion of the heat exchanger from not being in use. This dramatically affects the efficiency of the plant. We carry out checks to each condenser and bleed any air on each visit to ensure the best running conditions of the plant.

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Refrigerant System Standing Pressure

One of the ways to assess the condition of the refrigerant is the standing pressure. Only during factory shut down are all the chillers off for long enough for the system pressures to stabilize and so have a consistent standing pressure around the system. The pressure readings can be taken and added into our software to determine the composition and purity of the refrigerant and the presence of non condensables. Where the refrigerant is found to be in poor condition, maintenance can be arranged to rectify the issue.

Coefficient of Performance

The coefficient of performance is the cooling effect compared to the amount of electricity used. In an inefficient system, a small amount of cooling is achieved relative to a large amount of electricity used. In this age of environmental concerns, we carry out extensive measures and adjustments to improve the COP. Not only is an efficient plant cheaper to run, it is better for the environment too.

Control Panels

The control panels for the chillers in the photo are defunct. That is to say- the component parts are no longer manufactured. I am sure there is the odd circuit board rolling around on a shelf somewhere, but we fit state of the art controls. Our supplier builds bespoke panels exactly suited to each particular machine. They are plug and play with associated sensors, transducers and vane loading actuators supplied. The panel is fixed next to the chiller, wired in and ready to go. All settings come as default, so just the odd one needs to be modified. The panel can be easily integrated into the existing remote start stop and variable speed drives.

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To read more about shell and tube chiller condensers hit the Tag at the top of the page.

For further reading on Hydrofluorocarbon Refrigerants | Click Here


Maximus Chillers sign outside our chiller maintenance company office

Chiller Maintenance Company

Chiller Diagnosis

One of the most important parts of a chiller maintenance company is the diagnosis. If this is done wrong, the wrong parts are ordered and the return job goes wrong.

News Article No.7

For us at Maximus Chillers, it is imperative that we get the diagnosis right, so the return job goes easy. On a maintenance visit, a detailed Tick Sheet is completed with all the necessary readings and adjustments.

Chiller Maintenance Company Case Study

One of our engineers was on a maintenance visit recently and he found an electrical fault with a relay. An intermittent fault- so the most annoying to diagnose. The relay interlocks the compressor A1 run signal on the start contactor. The fault causing the relay to drop out was the high pressure condition. The high pressure switch was found to be in good working order with continuity back to the relay, so the relay was deemed to be not switching intermittently. The relay was changed with the available stock on site and the machine went back into seamless operation.

State of the Art Equipment

At Maximus Chillers we know that incorrect test equipment can lead to incorrect diagnosis. That’s why we have the highest quality equipment which is regularly inspected, replaced or calibrated. With a Fluke multimeter with fused leads- we diagnose the most complicated of problems. Sometimes a wiring diagram is not available, or the machine has been modified. Even wires disappearing into a conduit and ending up on the other end of the chiller can be traced and effectively diagnosed. You can rest assured that with the ongoing maintenance by Maximus Chillers- we will extend the useful life of any chiller.

Chiller Maintenance Company Technical Support Desk

For over the phone diagnosis, our contract customers enjoy the full benefit of our technical support desk. Faults are often something and nothing, or are just to do with how the machine was restarted. If we can get a chiller away over the phone, that saves us time and that saves you: the customer money too. Just part of what we call the MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere.

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Chiller Expansion Valves

We at Maximus Chillers have a comprehensive range of expansion valves, on the shelf, in our stores at our chiller maintenance company in Droylsden, Manchester. There are three commonly used types of expansion valve used on a chiller:

Pulse Expansion Valve

This is a simple design of a solenoid coil lifting a solenoid valve and opening the diaphragm in the expansion valve. This allows the refrigerant to pass from the high side of the system into the low side. A sensor either side of the evaporator feeds back to the controls. The controls work out the length of time the valve stays open and the length of time the valve stays closed. Quite a simple idea and quite reliable from our experience too. The replacement of parts are a straight swap.

Electronic Expansion Valve

Another type of valve we stock is the electronic expansion valve. Similar to the above, this valve uses a sensor either side of the evaporator to work out the superheat. Another method of working out the superheat is a sensor and a transducer. Either way amounts to the same thing: the controls work out the difference in temperature and saturation point. The mechanical part of the valve is a step motor which winds all the way shut when the chiller starts. This is so that the controls can register step 0. As the valve opens, the controls record the amount of steps and so opens and closes for a close control of the superheat.

Thermostatic Expansion Valve

A thermostatic expansion valve is a completely mechanical and stand alone part. The pressure in the bulb increases with temperature and so forces the valve open. We have the full range of orifices for the commonly used varieties of valve on the shelf. Each orifice is used for a different application, ranging from low temperature -40° saturation, through medium temperature 0° saturation, to high temperature 20° saturation. High temperature applications include laser chillers- the secondary refrigerant cools the oscillator and the laser head.

HFC Chiller Refrigerant

HFC refrigerant is being phased down to 21% by 2030. This is in accordance with F-gas guidelines and the emission reduction measures as defined in the Kyoto Protocol. This refrigerant, however, still remains to be the most popular type amongst chillers, with new chillers coming of the production line charged with, most commonly, R407c and sometimes R410a. R134a is also a popular chiller refrigerant most commonly used in flooded centrifugal chillers. The more the phasedown starts to pinch, the more the incentive to use a lower GWP (global warming potential) drop in refrigerant. This extends the useful life of the chiller, therefore removing the need to build a new chiller, with the associated high amount of carbon emissions.

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Chiller Evaporators

Eddy current Inspections by Chiller Maintenance Company

At periodic intervals according to the maintenance schedule, the end plates are taken off the chiller evaporators and the tubes are inspected. We have calibrated eddy current instrumentation to assess the integrity of the evaporator tubing. This equipment uses electromagnetic coils to produce eddy currents, the electrical impedance is then measured. It picks up any cracks, pitting or corrosion. The conclusions are mapped onto a chart showing the tubes which are likely to fail. These tubes can be taken out of operation to prevent catastrophic system failure in the future. The system can then be pressure tested in accordance with F-gas leak testing requirements to prove the integrity of the system. Just part of the joined up forward thinking of this chiller maintenance company.

Chiller Maintenance Company Lagging

On our maintenance visits, one of a long list of checks is to check the insulation and vapour seal. If the lagging is not in place correctly, moisture from the air forms as condensation on the steel shell. This is not visible, so the condition of the steel can deteriorate dramatically over time. Where the lagging is in good condition, industry guidance states that it should not be removed to inspect. Where the lagging is in poor condition, however, it should be stripped back to the location of a good seal to inspect the integrity of the shell. For low temperature glycol or brine applications, rapid deterioration occurs as the shell is defrosting and re freezing between production cycles or defrost cycles. We heat treat the steel to remove all the moisture, then grind off any rust, before adding a two kinds of specialist paint available for sale at Maximus Chillers. We then match into the old lagging for a good join with our off the shelf varieties of lagging. The lower the temperature of the application, the greater the thickness of the lagging supplied.

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To read more about chiller diagnosis hit the Tag at the top of the page.

For further reading on F-gas enforcement reforms visit RAC Magazine | Click Here


400 kw white chillers with panels open during air cooled chiller maintenance

Air Cooled Chiller Maintenance

A nice day to carry out air cooled chiller maintenance at a new site we have taken over in the South East.

News Article No.6

Our engineer attended site at around 9am with the risk assessment method statement having been sent in advance. A site survey was carried out to see if there were any additional risks. Should there have been any changes- the RAMS have a section for the additional risks and control measures. After gaining a permit to work, our engineer was issued with a security pass to access the chiller compound. Three chillers are located in the compound which feed air handlers for a critical application. Two of the chillers are multiple system, scroll compressor, air cooled chillers. The other is a single system screw chiller.

Program Settings During Air Cooled Chiller Maintenance

A complete download of the program settings is available in our engineer’s phone. This is to cross reference the settings, should one of them be accidentally changed by the maintenance engineers. Onsite engineers are the first port of call for chiller trip outs, with the responsibility to get the plant up and running. We offer real time assistance, over the phone from our Technical Support Desk and can send user manuals in PDF form, direct to their computer. The settings were found to be nominal, so a detailed analysis of the alarm history was carried out:

Alarm History During Air Cooled Chiller Maintenance

In reverse date order, the alarm history of all the systems was interrogated. There had been several system shut downs to carry out the periodic maintenance by the onsite personnel. The electricity having been shut down, there was a subsequent oil pre heating timer in the history too. On Chiller 2, System 1 however, there had been several low pressure trip outs. Our engineer decided to start the maintenance with this system by carrying out a full diagnosis of the low side of the refrigerant system:

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Superheat During Air Cooled Chiller Maintenance

The system runs on R410a refrigerant. This refrigerant has higher operating pressures in comparison with other HFC refrigerants. It has an efficient temperature range which can be seen on a pressure enthalpy chart. Below or above this range- the refrigerant loses efficiency and so has a lower coefficient of performance. The most common saturation point for this refrigerant is 0° which corresponds to a 7 bar suction pressure in the evaporator. Above this is the superheat of the refrigerant returning to the compressor. On this occasion there was found to be 26° of superheat and a suction pressure of 4 bar- close to the low pressure trip out. After careful diagnosis, our engineer decided to focus his attention on the expansion valve:

Thermostatic Expansion Valve

There are 4 forces acting on a TEV:

Liquid line pressure coming from the condenser.
Versus
Suction pressure down the equalising line from the far side of the evaporator. This compensates for the pressure drop across the evaporator and shows the true compressor side pressure.

Spring pressure acting upwards and closing the valve.
Versus
Bulb pressure forcing the valve open.

To reduce the superheat, the bulb should have forced the valve open. The refrigerant charge in the bulb acts upon the bellows to achieve this. The reason for the malfunction, on this occasion, was found to be the failure of the expansion valve orifice. It had become jammed- causing a shortage of refrigerant in the evaporator/ high superheat.

Latent Heat

Our engineer was carrying out the above fault finding with one compressor running and the other two being held off. This was to prevent a low pressure trip. Where chillers are left running with a high superheat condition, the reduced amount of latent heat causes a higher cost in electricity relative to refrigeration effect (COP) The refrigerant carries on superheating without absorbing latent heat- pointless and inefficient for a chiller.

Chiller Pump Down

For convenience, this chiller can be pumped down and valved off using the service valves. The evaporator can be worked on after breaking in procedures are carried out. Therefore, we have arranged for this to be carried out before fitting the new expansion valve parts. These chillers also have the ability to pump down the refrigerant on receiving a fault feedback from the electronic leak detector. This is an added measure to lower the environmental impact of refrigerant leaks.

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Subcooling During Air Cooled Chiller Maintenance

Cooling the refrigerant vapour down, through the latent heat phase and then subcooling the liquid down further. On System 2 of the same chiller, a subcooling issue was identified. 21 bar/ 36° saturation was normal for that system as defined by the fan speed controller. Now, the system pressure was higher at 28 bar/ 47° saturation, so our engineer decided to work out the subcooling. A very high reading of subcooling was recorded at 28° this was diagnosed to be due to non condensables in the refrigerant:

System Non Condensables

Non condensables are gases that will not condense, such as, air and nitrogen. If nitrogen is not vented properly and a deep vacuum then achieved, the gasses will remain in the refrigerant system. When calculating the subcooling, the readings work out incorrectly due the presence of the gasses. This can lead to false diagnosis. The remedy for the issue was to arrange a full refrigerant decant, pressure testing and dehydration, before charging with new refrigerant.

Efficiency

Having good subcooling values on a refrigerant system is critical to efficiency. Where there is no subcooling- the refrigerant has not fully rejected all the latent heat from the condenser. This can be seen when looking at a PH chart and plotting the pressures and temperatures. This heat remains in the refrigerant and adds to the system along with heat added from the compressor and heat from the process. This is another reason the coefficient of performance is reduced and so incurring increasing electricity costs for the plant.

Economizer

These chillers are also fitted with refrigerant economizers- one for each system. They work by diverting some of the refrigerant from the condenser, through a small expansion valve, then through a plate heat exchanger. The rest of the liquid refrigerant passes on the other side of the plate heat exchanger and so is further subcooled.

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To read more about air cooled chiller maintenance hit the Tag at the top of the page.

For further reading on chilled water visit Wikipedia | Click Here


Large white chiller being inspected to compose a chiller maintenance schedule

Chiller Maintenance Schedule

The chiller maintenance schedule in essence is as follows:

  • What is the plant? According to the asset list for that particular contract.
  • What are we going to do with it? The checks, procedures and diagnosis in the pursuit of the maintenance of the chillers.
  • How Often? The periodic maintenance schedule defining the required interval between visits to ensure seamless operation of the plant.

News Article No.5

Chiller N+1

N+1 is intrinsic in the development of a chiller maintenance schedule. N+1 means the amount of cooling required + the same amount again in parallel. It can also be represented as 2N. Two water system pumps are a good example: where the pipework splits in two- one pipe for each pump. When a pump fails, the redundant pump comes online. Chillers are arranged in parallel, in this way, on the water system. This redundancy allows for a stress free maintenance of the plant. The failed system can be rectified and brought back online while the redundant system takes the load.

Intervals of Chiller Maintenance Schedule

The intervals in the contract are influenced by the redundancy of the chillers on site. The less run hours the compressor does, the less maintenance is required. We at Maximus Chillers can tailor make a maintenance schedule exactly to your needs by looking at how much the chillers are used and how hard they work.

Load affecting Chiller Maintenance Schedule

For some applications, the chiller operates under a high load condition all the time, with a redundant system in standby. On other applications, the chiller works in minimal load conditions. Regardless of the load conditions, the chiller is critical to the cooling of buildings or for an industrial process.

Lead/ Lag of Chiller Maintenance Schedule 

An important thing to remember is to balance compressor run hours and bearing wear by rotating the lead/ lag duty of the chillers. This can usually be done in the in the sequencer (if fitted) by changing a program setting. Otherwise, the switchover controls can be changed on the off/hand/run toggle switches. Where manual changeover is required, the onsite engineers are usually conversant with the procedure concerning the water system pumps, valves and controls. During the maintenance, the stop checks can be carried out on the redundant system, while the run checks are carried out on the system which is online.

Chiller Maintenance Schedule for Reciprocating Compressors

Reciprocating compressors require a log of the compressor run hours. This is because the valves and bearings should be changed at pre prescribed intervals as laid down by the maintenance schedule. Particularly important to reciprocating compressors are regular oil changes and oil sampling- a small change in the result of an oil sample can prevent a serious compressor smash up. A check list including the model number and serial number is completed on each visit and kept in a file on site. This file can be consulted during diagnosis and maintenance to decide on the beast way forward with an on going issue.

Chiller Maintenance Schedule for Air Cooled Chiller Condensers

Air cooled chiller condensers can often be looked after by the onsite engineers in between maintenance visits. Just a quick brush down every few months is usually all it takes. Where the environment lends to a type of contaminant being collected on the condenser coils, an effective chemical is selected from our stores and used on the coil. Where there is an issue with the serviceability of the condenser, we can put together a plan to keep on top of it. We can even retrofit a new condenser- it’s what we at Maximus Chillers call the MAXIMUS ADVANTAGE™

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Shell and Tube Evaporators

The shell is made from a heavy steel sheet rolled into a circle. The seam is welded together to form a cylinder. The tubes are pushed though the tube holders which are made from steel and are welded into the shell of the evaporator. The tubes are copper because of its good thermodynamic properties.

Direct Expansion Evaporators

Direct expansion is achieved in an evaporator with a thermostatic, or electronic expansion valve. The refrigerant enters the valve from the condenser as a high pressure, hot liquid. The pressure drop on the evaporator side of the valve makes the refrigerant flash off into a cold, saturation point liquid and vapour mix. The liquid boils off, absorbing latent heat through the inside of the copper tubes. On the outside of the copper tubes is the return water from the process, or the cooling of buildings.

The parts of the maintenance schedule that relate to DX evaporators are:

Oil Pooling

The inside of the tubes are in the clean environment of the fridge system. This means they do not become fouled. A tube insulating issue can be caused on the inside by oil. If there are issues with the oil return system, the oil can pool in the evaporator. A low refrigerant charge can have the same effect. Written into the maintenance schedule are manual oil return and oil draining visits. During these visits, the monitoring of the refrigerant charge is also carried out.

Sensor Location

If a sensor is not located in its pocket correctly, or without sufficient heat transfer paste- it will read incorrectly back to the electronic expansion valve driver. This will cause the expansion valve to malfunction.

Pressurisation Units

A full maintenance of the pressurisation unit is carried out. This includes the pumps, controls and program adjustments as required. Incorrect pressure in the water system will cause a knock on effect of faults on the chillers.

Pump Sets

As above with chiller lead/ lag change over, water system pumps are manually changed over from lead to lag in the building controls. Carrying out this procedure reduces the chance of pump failure between visits. This is because it balances the pump run hours and so prevents bearing seizure after a long period not running.

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Flooded Evaporators

Flooded evaporators are the reverse of the above DX evaporators. The refrigerant is on the outside of the tubes, with water on the inside of the tubes. Gravity and refrigerant charge determine the refrigerant level in the condenser and evaporator. In between the two is located the liquid pipe with the orifice located in the pipe for the expansion of the refrigerant. The cooling water flows through the condenser tubes and off to the cooling towers. On the low side, the chilled water flows through the evaporator tubes and off to the process, or the cooling of facilities.

The parts of the maintenance schedule that relate to flooded evaporators are:

Tube Fouling

Because the condenser cooling water and chilled water systems are pumped through the pipes, the tubes become dirty over time. This occurs more often on the condenser as the water towers are open to atmosphere. Contaminants from surrounding buildings and factories gets into the water system and thermally insulates the tubes. This thermal insulation reduces the heat exchange through the copper tubes. The knock on effect is higher head pressures and eventually high pressure trip outs.

Specialist Cleaning Equipment

We at Maximus Chillers have in our stores the required equipment to carry out the cleaning of the tubes. Our engineers can attend site and liaise with the onsite engineers as regards the draining, strip down and lift out of the heat exchanger end plates.

Flushing Agents

A water sample is taken from the cooling and chilled water systems. These samples are sent off to our laboratory for analysis. Bacteria can build up in the water system causing slime- this can be rectified with a careful selection of chemical agents. Also, silt can build up- various chemicals are added to positively charge the silt and so carry it around the system to the strainer. Where the issue is caused by rust- an inhibitor can be added to prevent, or slow the oxidization of the steel.

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F-gas Chiller Leak Testing

The frequency of F-gas leak testing is determined by the size of the plant. This will be detailed in your F-gas file which is kept on site. Another record of this is kept by the chiller company at their registered office. The copies of the periodic leak testing sheets are kept by both parties. These detail the result of the test, refrigerant added to the system, refrigerant removed from the system and the required follow up actions. Some methods of leak detection are:

Visual Inspection

On each visit our engineers remove the coverings of the ends of the condensers and panels. This is to inspect the whole machine for a sign of a leak. Any potential leak is marked for future identification of the location. A visual inspection will always be backed up with a further diagnosis such as:

Superheat and Subcooling

These readings are taken during a maintenance visit to determine the refrigerant charge of the chillers. The engineer, however, has to bear in mind that the subcooling and superheat readings can read abnormally due other reasons.

Bubble up Leak Spray

Various makes are available from the suppliers. Each engineer having his own preference. We at Maximus Chillers stock leak sprays and a wide selection of other materials.

Electronic Leak Detectors

Fixed

This type of leak detector is installed in the chiller low down in the panel. This is because HFC refrigerant is heavier than air. The leaking refrigerant will tend to pool in the bottom of the various panels around the chiller.

Portable

Each of our engineers carries a portable sniff tester. It comes with an extended tip to get into the most tight and awkward places. The leak detector has a replaceable element inside the unit. It also comes with replaceable tips which can be swapped out periodically. They come with a portable plug socket and transformer to charge the on board batteries after use in the field.

Related Articles:
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Water Chiller Maintenance

Process Chiller Maintenance Visit

Chilled Water System Maintenance

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Glycol Chiller Maintenance

Chiller Maintenance Company

Chilling Plant Maintenance

For further reading on chillers and the chiller maintenance schedule- visit Better Bricks | Click Here


Chiller compressor failure of blue Grasso in enclosure

Chiller Compressors

System Testing for Chiller Compressors

Chiller compressors fail often the result of ineffective servicing and system testing.

News Article No.4

At Maximus Chillers, we carry out extensive tests during our visits to ensure that small problems are resolved before they become big problems. If we notice a reading starting to become abnormal, we can carry out the diagnosis, then do the necessary service. Some of the compressor readings we monitor:

Compressor Temperature

The suction, discharge, motor windings and bearing temperatures are recorded for comparison to previous visits. These are often available in the PLC for the chiller, or our engineer can take the readings with his test equipment. Problems with the oil system can be the cause of higher compressor temperatures, the system running outside of its nominal operating conditions is another reason. Magnetic drive systems have an advantage as they do not use oil.

Accelerometer

Portable vibration sensors are carried in of each of our company vehicles. This is an accelerometer to measure vibration. Along with other system readings, we keep an on going record of the vibration levels around the compressor. When internal components are coming out of alignment due to wear, this causes an out of balance condition in the compressor. This, in turn, causes a knock on effect- causing other components to go out of balance. Catching this condition early will prevent a compressor smash up resulting in the replacement of expensive internal components.

Oil Analysis

Another way of preventing big problems to occur is periodic compressor oil testing. Samples are taken, usually on alternate visits, which are sent off to a laboratory for analysis. The acid level is tested to provide pre warning of a potential compressor motor windings burn out. This is because acid in the compressor oil rots through the electrical insulation on the motor windings. The presence and quantity of white metal and yellow metal is analysed too. This is a window through to a component starting to wear inside the compressor.

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Screw Chiller Compressors

The compressor in the photo is a screw compressor. It operates with ammonia refrigerant. This refrigerant is usually used for low temperature applications, mainly associated with food production. This compressor, however, has a 1° refrigerant saturation and is used to cool computer rooms. Common causes of compressor failure on this kind of compressor are:

Leaking Compressor Castings

The various compressor components are sealed together using ‘o’ rings or paper gaskets. ‘O’ rings are especially prone to leaks due to work hardening and flattening of the sealing face of the ‘o’ ring. The system can be pumped down and the compressor valved off. Then, our lift and shift team can remove the compressor to our remanufacturing facility for strip down.

Leaking Shaft Seal

The mating surface of a shaft seal has a mirror smooth finish. This is to reduce friction and aid with a better seal. Over time, this starts to wear, causing an ineffective seal and a leak of refrigerant and oil. A service visit can be arranged to change the shaft seal on site. The shaft couplings can be split, the shaft seal can then be removed and replaced. A quick job, then the machine is up and running again.

Slide Valve Potentiometer

This is an electronic device with a slide attached to the moving compressor slide valve. The device has a start and an end position programmed into it during commissioning. The potentiometer converts the slide valve position, usually into a 4-20mA signal which is fed back to the chiller PLC. They are prone to reading out or the reading being jammed in one position. This results in a trip out from the controls, as the controller is not able to determine the true position of the compressor slide valve. We have an off the shelf stock of slide valve potentiometers for the various compressor range. A service visit can be arranged to replace the part after diagnosis has been carried out.

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Centrifugal Chiller Compressors

Centrifugal compressors are a very reliable kind of compressor but when they go wrong, they can go wrong in a big way. Compressor overhaul is expensive, this can be carried out onsite, or a better option is a lift and shift to our remanufacturing facility. Proximity sensors are usually fitted to monitor the distance between the impeller and the casting. This is an added protection along with the other sensors and transducers around the compressor.

MCS

We are on account with Micro Control Systems- an American company who specialise in building panels to order for specific chiller compressors. We easily fit this control system to any compressor to control the loading of the vanes in accordance to the available load from the process. The control panel has previously been fitted to other machines of the same model number, so any teething issues have already been ironed out. Maximus Chillers can achieve seamless operation of your plant.

Oil System for Chiller Compressors 

Newer centrifugal compressors are oil free so as to eliminate any of the service issues relating to oil. There are a substantial amount of compressors, however, that use oil to lubricate the bearings. This kind of compressor, if properly serviced, can last for 50 years. The oil system picks up impurities which are caught by various filters. These filters can be changed or cleaned according to the prescribed service schedule. Our engineers make sure that spares are ordered and kept onsite prior to a visit.

Cost Effective

Our visits and ongoing upkeep of your plant saves money. Money spent as a preventative measure saves so much more money in the long run. With competitive prices on specialist internal compressor parts- Maximus Chillers completes the picture. When compressor failure occurs, you are in safe hands with years of industry experience invested in each of our engineers.

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Scroll Chiller Compressors

High Discharge Pressure

With high discharge pressure, there is a corresponding increase in discharge temperature. This means that the compressor is operating beyond its recommended values. The cause of this is often a poorly maintained condenser. Especially on industrial chillers, there can have been gaps in the schedule where the condenser was not correctly serviced. This condition is often rectified easily by an onsite engineer by giving it a brush down. Where the fins are bent over- we carry a specialist tool to straighten them back out- how they came out of the factory. We also use different formulas of chemicals to rinse the various kinds of dirt from deep within the fins.

High Suction Pressure on Chiller Compressors 

Some chillers are used where very high water temperature can come back from the process if the chiller were to be off line for a short period. Usually, this happens in factories where certain industrial processes are being carried out. When the onsite engineers start the plant back up, the chiller experiences a high heat load to deal with.

MOP Expansion Valves

Maximum operating pressure expansion valves limit the pressure in the evaporator to a given level, regardless of the available heat load from the process. They do this by having a limited amount of liquid refrigerant in the bulb. When this runs out, the power element cannot push the orifice open any further- thus limiting the suction pressure. This is important to prevent scroll compressor failure as it prevents putting added strain on the compressor motor windings due to high suction pressure.

Oil and Refrigerant Shortage

Where there is a shortage in refrigerant, there follows a low oil level condition. The refrigerant mass flow rate, carries the oil around the system and back to the compressor. This is greatly impaired when the chiller is short of gas. The oil cools the compressor and lubricates the shaft bearings. These bearings and other internal components wear down and seize causing failure. Maximus Chillers can put together a package to minimise chiller compressor failure.

Chiller Refurbishment Supplier

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Visit Wikipedia to read more about impellers which are used in centrifugal compressors | Click Here


Chiller service company's PLC and relay board in a panel

Chiller Service Company

Chiller Service Company Diagnosis

System Testing

A chiller service company can carry out diagnosis even when a wiring diagram is not available- our engineers can trace the wiring around the chiller.

News Article No.3

This often aids with diagnosis even when there is a wiring diagram, as to have your eyes on a component often makes more sense than a symbol. In any case, our engineers carry out system testing with Fluke multimetes and ammeters. We carry a range of thermocouples and probes to be used in conjunction with our calibrated digital thermometers. We use these along with comparators to carry out leak testing…

F-gas Leak Testing

According to the frequency dictated by the quantity of refrigerant, we use the above test equipment to carry out F-gas leak testing. First, we have a visual look around the chiller for a sign of a gas leak. All parts of the pipework and system components are inspected. Then, we carry out a full refrigerant diagnosis to determine that the refrigerant system is operating with a full charge of refrigerant. The report for each chiller being completed and filed in the onsite F-gas leak register. A history can be built up to assess the serviceability of the plant and the frequency of leaks.

Chiller Service Company Monitoring

Where intermittent faults are concerned, on going system monitoring is required. If the job is not progressed on each visit, there is little point in a call out. We carry out tests during monitoring and ensure that the wiring is tight. Hopefully, waiting for the fault to occur whilst next to the machine. Alongside this, we rely on a report from the end user, as regards, the symptoms and the circumstances of the chiller when the fault occurred. From this we extrapolate the diagnosis and decide the next step to take. This may be to attempt to move the fault to another machine or, at least eliminate one thing each visit.

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Chiller Service Company Evaporators

Shell and Tube Evaporators

These have a rolled steel shell, welded down the seam with and end plate on either end. The water system pipes can be bolted to the sides or the end. The endplate can be removed for access to the waterside of the tubes. A strainer is fitted to the inlet to catch any foreign objects that may have been carried around the water system. Inlet and outlet gauges are fitted for the monitoring of the water system readings during a service visit. On larger chillers the screw or centrifugal compressor is mounted directly on top of the evaporator- sucking directly off the top of a flooded evaporator…

Flooded Evaporators

This kind of evaporator has the refrigerant in liquid form on the outside of the tubes. These are a rack of copper tubes extending through the length of the shell. The warmer process water running through the tubes causes the refrigerant to boil off. A sight glass is usually available to check the state of the refrigerant evaporating on the copper tubes. The suction from the top of the evaporator goes round a baffle so as to prevent the slug back of liquid refrigerant into the compressor. The refrigerant flow into the evaporator is controlled by the expansion valve…

Expansion Valves

This takes the form of a fixed size orifice on the liquid line in between the shell and tube condenser and the flooded evaporator. The size of the orifice previously being calculated to match the mass flow rate of the refrigerant dictated by the compressor. Some newer systems have a variable orifice for the more efficient running of the plant. This is controlled electronically along with the loading of the compressor, relative to the available load condition.

Multiple System N+1

Smaller DX evaporators are usually multi system. This gives an N+1 redundancy of the plant. Indeed, when one side of a 2 system evaporator is having service work carried out, the other side continues to operate normally. Thinking ahead and allowing for additional capacity is essential when the application is critical, such as, a data centre or a hospital. When a redundant system comes online due to a failure- getting the system back up and running is a matter of urgency. For this we offer same day delivery of parts and a fully stocked mobile workshop.

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Chiller Service Company Condensers

Various configurations are employed to ensure good air flow through the chiller condenser fins. The most popular being a ‘v’ condenser as the surface area is increased with this design. Powerful fans are used to reject the air and heat upwards and away from the chiller. Where system location causes the recirculation of air, duct work can be fitted to direct the air away from the chiller.

Pressure Transducers

Johnson Controls

A popular kind of pressure transducer used on condensers is Johnson Controls. These can be bolted onto the refrigerant discharge pipe to sense the system pressure. They have a 5vdc input that comes into the transducer on a red wire, a black wire is the ground and a white wire is the signal back to the fan speed controller. The transducer has a minimum to maximum range, so a chart can be used to determine if the signal is reading back correctly. On chillers where the transducer is wired directly in the controller- calibration can be carried out to offset the readings.

Keller

Another kind of pressure transducer is the 4-20mA type. It sends a mA signal back to the controller or the fan speed controller. 4mA is the minimum position, so this relates to the minimum of the transducer pressure range.

R134a Refrigerant

R134a refrigerant operates at a lower pressure in a condenser than the other commonly used HFC refrigerants. If you were looking for a chilled water set point of 6° in the UK ambient for example, the R134a refrigerant saturation on the high side of the system would be around 36° Latent heat from the water system and heat added into the refrigerant from the compressor are rejected from the condenser. As the refrigerant passes down the condenser tubes, cool air blowing across the outside of the tubes, cools the refrigerant vapour down through the latent heat phase and into a subcooled liquid.

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Chiller Service Company Compressors

Centrifugal Compressors

This kind of compressor has a lower volumetric efficiency compared with the positive displacement compressors below. This is because the refrigerant is compressed using centrifugal force off the tip of the impeller, instead of being mechanically compressed. The advantage of this kind of compressor is a high mass flow rate of refrigerant. These compressors are used in factories where a large amount of chilled water is required to cool the process. They are also used in countries where district cooling is used. The chillers are arranged in rows in a chiller hall and are piped into the district cooling loop.

Screw Compressors

Oil used to lubricate the bearings is also used to create a seal between the rotors. Computer aided design (CAD) software and computer numerical control (CNC) grinding machines are used in the construction of screw rotors. The shape of the rotors is designed to compress the refrigerant along the screw. The length of the screw that is available to compress the refrigerant can be adjusted with a slide valve. Any stage of loading between 0- 100% can be achieved. This is regulated with a slide valve potentiometer. Screw compressors are very reliable and have a long service life. They also have a low vibration reading which ensures a lower instance of refrigerant leaks around the compressor.

Scroll Compressors

A service free compressor. Service free assuming that the rest of the system is functioning correctly. This kind of compressor relies on oil migration around the system. The oil is entrained along the inside of the pipework, around the system and back to the compressor. An oil level sight glass is fitted into the body of the compressor at the required level. Refrigerant shortage can cause the oil to stay in the bottom of the evaporator, causing a low oil level condition in the compressor. Chiller service companies can be scheduled to attend site to drain the oil, then pump new oil into the compressor.

Compressor Failure

When any of the above compressors fail, you are in safe hands with Maximus Chillers. We have the capability to lift and shift the compressor to our remanufacturing facility for a full overhaul. The reason for the failure is diagnosed to ensure the new compressor does not fail for the same reason. Improving the reliability of your plant and extending its life is what we are all about- if we can reduce your service costs- that makes us happy! All temperatures and pressures are recorded to ensure the replacement compressor goes into seamless operation.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Read more about pressure sensors on Wikipedia | Click Here


Large air cooled brown chiller with test equipment during planned preventative chiller maintenance

Planned Preventative Chiller Maintenance

Featuring planned preventative chiller maintenance- in a series of longer, in depth news articles:

News Article No.2

This time concentrating on the checks, adjustments and diagnosis our engineer carries out while on site. We can extend the life of your plant and reduce energy costs- just with the effect of our maintenance. As well as completing a detailed checklist which is sent in to your office in PDF form, our engineer carries out extensive F-gas leak testing.

Planned Preventative Maintenance of Chiller Controls

The first part of the maintenance is carried out to the controls of the redundant systems. This is because all the pressures and temperatures should be reading the same. If not, this is an opportunity for:

Sensor Calibration

Before calibrating a sensor that is reading out, our engineer carries out a diagnosis to assess the serviceability of the sensor. With NTP (negative temperature coefficient) and PTC (positive temperature coefficient) sensors, the resistance is taken at a given temperature, which is then compared with a chart. With pressure transducers the 0-5vdc feedback signal is analysed to see if it is within the allowable tolerance. Once this diagnosis is complete and the sensor is deemed to be in good working order, our engineer will then calibrate the sensor. A password is entered into the PLC (programmable logic controller) to gain access to the service menu. From here, he can select the particular sensor, then offset it by the required amount. A lot of controls are not linear, that is to say, a sensor reading 2° high being reduced by 2° may not calibrate correctly. An amount of trial and error is often required, also the monitoring of the sensor against a digital thermometer at various temperatures.

Program Settings and Timers

Each program setting and timer in the various menu levels is checked against the previous maintenance checklist. Sometimes these are changed accidentally by the onsite engineer when looking for something else- it is easily done.

Planned Preventative Chiller Maintenance of Safety Chain

Each component on the safety chain is manually tripped or the fault condition is replicated to cause the device to trip. This part of the PPM (planned preventative maintenance) is essential to ensure the safety chain protects the chiller during a fault condition. Compressor failure or evaporator freeze up can occur with dramatic cost implications. We routinely prevent small problems, such as a faulty switch, becoming big problems.

Planned Preventative Chiller Maintenance of Wiring

Each wire on the chiller is checked for tightness including the fans (on air cooled chillers) the compressor motor connectors and compressor contactor contacts. Loose line wiring will cause breaker and fuse faults. Loose control wiring will cause error messages and chiller faults. This is a call out in between visits that can be eliminated. With the effect of our maintenance, any chiller becomes more reliable and has lower energy costs.

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After the above stop checks are carried out, system run checks are carried out:

Superheat

Using R134a refrigerant as an example, the refrigerant pressure will be 1.9 bar at 0° This refrigerant is in the HFC (hydrofluorocarbon) family- a commonly used refrigerant. If the refrigerant vapour returning to the compressor is excessively superheated- this is a sign of system issues. Here are some of the causes for a high superheat condition:

Refrigerant Shortage

Not enough latent heat being absorbed by the refrigerant in the evaporator. This allows the refrigerant to carry on superheating with the available heat load. Refrigerant leak testing is required to identify any leaks. The history of maintenance checklists can be consulted to see if the issue had been deteriorating over several maintenance visits.

Expansion Valve Failure

A thermostatic expansion valve operates with a higher superheat value, whereby an electronic expansion valve has a much closer control. In either case, our engineer will be accustomed to the nominal readings.

Thermostatic Expansion Valves

This type of valve is operated with a power element and orifice. A bulb is clamped onto the suction pipe which is connected to the power element via a capillary tube. The power element is pressurised with the same refrigerant as in the chiller. Some of this refrigerant is in its liquid phase, so with an increase in temperature, there is a corresponding increase in pressure. This pressure acts against the diaphragm and so pushes the orifice open. The orifice allows more refrigerant through the valve. When load conditions change and there is a reduction in heat load, the reverse happens- the orifice closes and reduces the amount of refrigerant through the valve. When the power element looses its charge- the orifice shuts down causing a high superheat condition. A low pressure trip out can also occur.

Electronic Expansion Valves

This type of valve uses sensors on the liquid and vapour sides of the evaporator, or a transducer and sensor vapour side of the evaporator. This is so the program can work out the superheat value. If the sensors are faulty, the valve will not operate correctly and a high superheat condition may occur. If the step motor or driver have failed- replacement parts are required.

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Subcooling

This is the measurement of the refrigerant condition in the condenser. Air cooled condensers are particularly popular in the UK as the ambient conditions make them very efficient. Shell and tube condensers are used on lager systems- these are cooled down using a water tower. When there is a refrigerant shortage, the liquid does not stay in the condenser long enough for it to subcool sufficiently. Some of the refrigerant stays in its vapour phase. With not enough latent being rejected in the condenser- the chiller’s COP (coefficient of performance) will be reduced. This means high energy consumption relative to the refrigeration effect of the chiller. This condition can be remedied with a scheduled visit from one of our team.

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Air Cooled Chiller Planned Maintenance

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Process Chiller Maintenance Visit

Chilled Water System Maintenance

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Glycol Chiller Maintenance

Chiller Maintenance Schedule

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For further reading on the subject of  preventive maintenance on Wikipedia | Click Here


A pile of completed chiller maintenance checklists on a table

Chiller Maintenance Checklist

Introducing  a series of in depth news articles, this time featuring the chiller maintenance checklist:

News Article No.1

This article has been written with you- the customer in mind. Read below for practical advice on how to keep your chillers in the best condition.

Each day when you walk round, you can check to see if your plant is starting to malfunction. Become accustomed with the usual readings to help you diagnose the faults.

Here are the things to check for and how to remedy them:

Water System Pressure

Keep an eye on the pressure in the water system.

Small Chiller Maintenance Checklist

On a small chiller, there will be a water outlet pressure gauge. Make a mark on the gauge where the pressure is when the chiller is in good working order. You can use this mark to notice if the pressure is starting to drop off.

Strainer

The most common cause for low water system pressure is a blocked strainer. It is usually a ‘Y’ type with a bolted fitting. With the chiller off and the water system valves closed, unscrew it and check for debris. If it is blocked, make a note of how long it took to block, then add the cleaning of the strainer into the periodic maintenance schedule.

Pump

Ensure the pump rotation is correct by checking that the cooling fan is sucking into the pump. If it is going backwards: isolate electrically, then swap any 2 of the 3 phase wires. Brush down the inlet to the cooling fan to ensure good air flow and a cool pump motor.

Large Chiller Maintenance Checklist

On a large chiller, the water system pressures may be available in the controller- have a look through the menus. The pressure will be measured in bar. Another popular method on a large chiller is a flow meter. This may be a stand alone device on the chiller panel, or on a control panel nearby. It will read in m3/hr. Check to see if the pressure or flow is lower than usual. If so, ring one of our trained professionals.

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Water System Temperature

The chiller should be:

  • Matching the load and running continuously.
  • Loading and unloading in sequence with other chillers.
  • Going through a cycle and achieving set point.

In any case, you will become accustomed with the usual chilled water temperature according to varying load conditions. If the plant is struggling to achieve set point, or is running higher than usual- this is a sign of system faults.

Walk along the chillers that feed the same water system and make a log of the faults showing on the controllers.

Here are the things to check for high water system temperature:

Small Chiller Maintenance Checklist

Low Refrigerant Pressure

If it has a low pressure gauge, look to see if the pressure is lower than usual. If so, this is a sign of refrigerant shortage in the plate evaporator. A scheduled visit from one of our trained engineers to carry out a pressure test can be arranged.

Breakers

Look for any breakers that have tripped in the panel. One reset can be carried out by a qualified onsite electrician. If the fault reoccurs- ring our support team. If the scroll compressor has tripped, check to see if the compressor is hot. If so, isolate and do not attempt a restart.

Condenser

A blocked condenser will inhibit the rejection of heat. Brush it down and give it a rinse with water. A common occurrence onsite with some condenser designs is a panel being left off with the chiller running! This happens when the onsite engineers are fault finding another issue with the chiller. The fans will suck through the opening as this is the easiest path. The gauge will be higher than usual as the condenser builds in pressure. A high pressure switch trip out will occur.

High Pressure Switch

To locate the switch- first identify the discharge pipe. It is the smaller of the 2 pipes on the compressor. The high pressure switch will either be bolted onto the pipe, or a thin pipe will lead from the discharge to the frame of the chiller. In any case, you are looking for a small box with a button and a wire leading to the panel. Press the button and you should hear it click. If this fault reoccurs- ring our technical support desk.

Large Chiller Maintenance Checklist

Suction

Should there be a refrigerant shortage, the controller will display a pre alarm: suction limiting. This is the controller preventing the compressor from loading up to prevent a low pressure trip out in the shell and tube evaporator. As above, one of our team of engineers can be sent to site to resolve the issue.

Discharge

If the controller is showing: discharge limiting- this is a sign of a condenser issue. A full strip down and cleaning of the tubes may be required. Ring our technical support desk for further advice.

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Chiller Remote Monitoring

We at maximus chiller can install remote monitoring systems to your chillers so we can fault find and diagnose from a laptop. This means we can give you real time advice over the phone. Now you are accustomed with our chiller maintenance checklist- you can give feedback regarding the plant to assist our engineer.

Parts

For our contract maintenance customers: a range of commonly used parts are kept onsite to reduce downtime. We can give practical, step by step advice on the fitting of parts. We often carry out video calls with our customers, as chiller data plates, parts and components can be easier to show than describe.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

To read more about air cooled chiller maintenance click the Tag at the top of the page.

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Process Chiller Maintenance Visit

Chilled Water System Maintenance

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

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Glycol Chiller Maintenance

Chiller Maintenance Schedule

Air Cooled Chiller Maintenance

Chiller Maintenance Company

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Read more about chillers on Wikipedia | Click Here


Yellow oil drums, ammonia refrigerant cylinders and flammable flushing agent of chiller parts supplier

Chiller Parts Supplier

Chiller Parts Supplier of Compressors

Centrifugal Compressors

As a chiller parts supplier, all kinds of centrifugal compressors are remanufactured in our workshop. With an over head gantry crane and specialist equipment to hand- Maximus Chillers completes the picture.

Screw Compressors

Screw compressors are remanufactured on the bench. With compressed air and bearing tools- our skilled screw compressor technicians are seasoned in high tolerance measurements.

Scroll Compressors

We have a range of off the shelf Copeland compressors for a fast lead time on process chiller repairs.

Chiller Parts Supplier of Condensers

Air Cooled Condensers

When the condenser on an air cooled chiller is in poor condition- our site survey team will attend to measure up for a new bespoke condenser.

Shell and Tube Condensers

This type of condenser is used on water cooled chillers.

Chiller Parts Supplier of Evaporators

Shell and Tube Evaporators

This is the most popular type of evaporator for large chillers. The low temperature refrigerant is on the outside of the tubes in liquid form. The water is pumped through the tubes, releasing heat from the process into the refrigerant. This is latent heat as the liquid refrigerant boils off into a vapour.

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Chiller Parts Supplier

Vibration Eliminators

We have all the sizes of anacondas on the shelf in our stores. This saves on the delivery time to site when your process if off due to the chiller. Maximus Chillers will get you up and running- fast!

Flushing Agent

For when things go wrong… we stock a solvent based flushing agent which is blown through the system with nitrogen.

Refrigerant Economizers

These are another term for a subcooler. If the refrigerant is further subcooled after the condenser- the system will run more efficiently.

Chiller Parts Supplier of Controls

Pressure Transducers

We can make temporary repairs to faulty pressure transducers using our test equipment. This will keep your plant running while the part arrives onsite.

Chiller Parts Supplier of Ammonia and HFC refrigerant

A full selection of refrigerants are available in our stores including: anhydrous ammonia, R407c, R134a and R410a.

Chiller Parts Supplier of Compressor Oil

Low, medium and high viscosity oils in 5ltr cans and 20ltr drums are ready for shipping from our storage area.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

To read more about chiller evaporators- click the Tag at the top of the page.

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Read more about the centrifugal vapour compressor at the Institute of Refrigeration | Click Here


Brazing equipment box and vibration eliminators during packaged chiller service

Packaged Chiller Service

Packaged chiller service due to a refrigerant leak, resulting in a trip out. This visit was to identify the leak and get the plant back online.

Leak Testing During Packaged Chiller Service

Nitrogen was added to the system to aid in the identification of the leak. All parts of the system were checked, including the removal of lagging around the couplings onto the evaporator. The leak was found on a poor quality ‘eliminator’ which had rubbed through on the evaporator.

Vibration Eliminators

We decided to fit high quality vibration eliminators- see picture. These are fitted one in the horizontal position and the other in the vertical. They absorb both directions of vibration then they are clamped to the chiller frame.

Brazing During Packaged Chiller Service

The pipework brazing was carried out with all combustible materials being removed from the work location. A permit to work was opened with our engineer as the responsible person. A half hour fire watch was carried out on completion of works.

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Pressure Test During Packaged Chiller Service

The pressure testing was carried out using nitrogen. As nitrogen is an inert gas, it will not cause other potential risks to the chiller and other personnel. The pressure test was a pass, so the next phase of the job could be carried out…

Vacuum Pump

Each engineer carries a 10 cfm vacuum pump. This high capacity ensures a fast vacuum. The Torr gauge was fitted to the system and 2 Torr was pulled.

Refrigerant Saturation

In the cylinder, the saturation of R407c is 7 bar at 11° The refrigerant in the cylinder is in its liquid phase with vapour on top.

Subcooling

On run testing the chiller, the subcooling value was found to be nominal at industry standard level.

Superheat

The superheat was adjusted, little by little, with the charging of the refrigerant until a good value was achieved. This was tested across all loading conditions for the rest of the visit.

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Carel controller and tick sheet during chilling plant maintenance visit

Chilling Plant Maintenance Visit

On this chilling plant maintenance visit, particular attention was made to compressor loading. This was to ensure that the compressors are capable of operating at 100%. With summer now here- we want the plant capable of running at full capacity.

Controller Loading Timer

On start up, the controller goes through a timer, this is to prevent the compressor from loading up too quickly, achieving set point and going off. With available load, the compressor would start back up and a short cycling condition occur. With 5 minute intervals, the controller brings System 1 screw compressor on at 25%. Then System 2 screw compressor on at 25%. In stages, the controller loads up the compressors until it matches the load.

Compressor Loading Solenoid Coils

These are 24vac. The controller sends out a run signal through the solenoid coil which magnetises the lift valve inside.

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Compressor Loading Solenoid Valves

As the valve lifts, discharge pressure oil passes through a channel and pushes the slide valve open a 25% stage. There are 4 valves for the 4 stages.

Chilling Plant Maintenance Visit at 100%

The chilling plant being maintained on this visit was now running at 100% on both systems. The system readings can easily be read by following the menu in the Carrel controller. Superheat and subcooling readings were found to be within operating limits and a good read back on the water system.

Compressor Unloading

At the end of the day, the three way valves on the air handlers closed down according to the BMS schedule. This meant that the water was diverted away from the heat exchangers in the air handlers. This return water had not picked up any heat, so the controller started unloading the compressors. It did this through 75% to 50% then 25% until the chilling plant water system had achieved setpoint.

Off Cycle at Chilling Plant Maintenance Visit

The BMS stops the chiller with the remote start/ stop signal. Should the BMS malfunction, the chiller would stay off most of the night anyway. The water system pump adds heat into the water system. Therefore, every so often enough load would be available to bring one system on at 25% for a short while.

To read more about chilling plant maintenance click the Tag at the top of the page.

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7 large air cooled chiller condensers maintained with 12 fans each

Air Cooled Chiller Condenser Maintenance

Air cooled chiller condenser maintenance at Maximus Chillers. The condensers in the picture are a row of 6. These are remote from a row of 6 chillers, located in a plant room in the building below. The chillers are 750 kw single screw compressors with a control panel located to the side of each. On this visit, the emphasis of the maintenance was scheduled as being to the condensers.

Fan Speed Controllers

The refrigerant for the systems is R134a, so to allow for the saturation of the refrigerant, 8 bar is the head pressure set point. This pressure corresponds to the desired condenser temperature of 36°. Subcooling of 6° to 8° is achieved during the nominal operation of the plant. Each fan speed controller runs the 12 condenser fans together. Other condenser designs where fans bang on forwards and backwards cause vibrations resulting in reoccurring leaks on the condenser. Chiller No. 2 had tripped during a “discharge override” system message. On inspection of No. 2 condenser- the fans speed inverter had tripped on “over temperature” alarm. The panel fan, which is the kind to cool computers, was found to be still trying to run but seized. This failure had caused the alarm on the inverter. The panel fan was replaced from the stock of parts in the onsite stores. The chiller was reset and a detailed Tick Sheet was completed noting the occurrence of this fault on arrival.

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Air Cooled Chiller Condenser Wash Down Maintenance

Because of the large size of the plant, the customer had installed a fireman’s hose for the wash down of the condensers during air cooled chiller maintenance. This is located in the free space beneath the condensers. It is fitted to a portable buggy so it can be moved under each condenser. Setting the nozzle to the correct attitude, our engineer moved the buggy sideways, so as to rinse the condenser in the direction of the fins. The condenser was relatively clean as the on site maintenance engineers carry this task out as part of their scheduled maintenance.

To read more about air cooled chiller maintenance click the Tag at the top of the page.

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2 Torr showing on a gauge during process chiller vacuum service

Process Chiller Vacuum Service

During a recent process chiller vacuum service, our engineer achieved a deep vacuum of 2 Torr. This is the same pressure as if the Torr gauge had been fitted directly to the vacuum pump.

Torr Gauge

The Torr gauge was fitted to a refrigerant hose. The refrigerant system uses a different kind of fitting used for breaking in. Therefore, an adaptor fitting was used to go between the two kinds of fitting. A specialist sealant was used between the adaptor fitting and the refrigerant system and another sealant was used between the adaptor fitting and the refrigerant hose. This completed, the Torr gauge was located in a convenient location for inspection on achieving a deep vacuum.

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Process Chiller Vacuum Service Pump

Each of our engineers is issued with a high capacity 10cfm pump. Only the best equipment will do at Maximus Chillers. The oil was changed as per standard industry procedures and the correct level of oil was checked. The vacuum pump was ran up to operating temperature for half an hour with the inlet valve closed. This was to ensure the correct operating temperature of the oil was achieved before load was given to the pump. A steel braided refrigerant hose with bolted ends fits with the service ports on the refrigerant system. Therefore, adaptor fittings were again used to get between this hose and the vac pump.

Dehydration Process

The purpose for evacuation is the removal of moisture from the refrigerant system. Air contains usually around 50% relative humidity of moisture carried within it. Air had ingressed into the system during the works that had been carried out. The boiling point of moisture is 100°C at 760 Torr (1 bar absolute: Earth’s air pressure at sea level) This boiling point drops, corresponding to pressure until at 15°C the boiling point of water is 10 Torr. The boiling point of water at 0°C is 5 Torr. Therefore, with our vacuum pump achieving 2 Torr, a dry system is capable of being achieved regardless of the UK ambient temperature. Also, various heaters were used to speed up the process. Eventually the pressure in the refrigerant system was recorded at 2 Torr.

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Controls panel open during chilling plant maintenance

Chilling Plant Controls Maintenance

Prior to this chilling plant controls maintenance visit, another contractor had changed some of the settings and adjustments in the controllers. They did this while they were diagnosing a fault with the water system and the pumps. Therefore, this visit was to recommission the plant and to resolve the issues resulting from the adjustments.

Chilling Plant Flow Controls Maintenance

The flow controls were found to be set wrong. Therefore, our engineer adjusted the pumps, then various valves on the water system, a little at a time, while monitoring the controller. Full load and part load readings were taken until they came to within standard industry limits.

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Compressor Run On Time

A timer had been adjusted which made the compressor wait to stop after reaching 0% on achieving set point. In the meantime, some more heat would build up in the water system and the compressor slide valve would open up a little. The result was that the compressor would run for an hour with the slide valve shut most of the time. The oil pump carried on pumping during this time resulting in a head of oil building up in the discharge pipe- all the way back up to the oil separator. Then, a low oil level fault had occurred. This being confirmed by the sight glass on the oil separator. The compressor had enough oil charged into it to allow a start up. During the start up, a low oil level timer counts down. As soon as the compressor loaded and started pumping, the oil level returned to the correct level on the sight glasses. The timer was adjusted along with the dead band to ensure the chiller off cycled after achieving set point.

Slide Valve Potentiometer

The slide valve potentiometer has a configuration mode button. It can be pressed to set the 4mA or 0% position. This is the usual position of the slide valve as a spring and 2 drain valves return it to the start position. The slide valve can then be manually opened in the program. Then, the potentiometer button can be pressed to set the 20mA or 100% position. “Chattering” can occur on the fully closed position so a setting is available to only close the slide valve to 2%.

To read more about chilling plant maintenance click the Tag at the top of the page.

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An engineer filling blue oil drums during industrial chiller maintenance

Industrial Chiller Maintenance

Reciprocating Compressors

Industrial chiller maintenance including a reciprocating compressor with 8 cylinders. They always have an even number of cylinders so that the compressor is balanced.

Open Drive

Because the refrigerant being used in this article is ammonia, the compressor is open drive. This is because ammonia corrodes the copper windings of the electric motor. An open drive compressor needs a shaft seal to prevent oil and refrigerant escaping from the system. These shaft seals are prone to wearing down and leaking. They have two mating surfaces that have a finish so smooth that it is like glass. Any oil leaking out of the system collects in a pot. This pot is monitored for the rate at which it fills up and so the deterioration of the shaft seal can be monitored. The swap out of the shaft seal can be arranged at a convenient time. This evolves the splitting of the shaft coupling to allow access to the seal.

Semi Hermetic

This means that the electric motor is internal to the compressor. Hermetic meaning sealed and semi meaning that you can bolt components off, such as, the cylinder heads. There is a significant advantage with this type of compressor design as there is no shaft seal. The compressor motor windings are also cooled by the suction vapour returning to the compressor from the refrigerant system. This compressor design is used with HFC, HFO, CO2 and Propane refrigerants. There are some semi hermetic compressors that are suitable for ammonia where the windings have been sealed from the refrigerant.

Scheduled Strip Down

This kind of compressor has a lot of moving parts that need to be replaced according to the run hours of the compressor. Failure to do so will lead to the compressor going out of balance and an expensive compressor smash up occurring. Usually during a smash up, a connecting rod will fly off causing oil to spurt out from the gallery. This causes a low oil pressure fault which stops the machine. One smash up which I have seen involved all the con rods staying on and flailing round the inside of the compressor. One cylinder was still working, the compressor still running and a sump full of different sized triangle pieces of metal! This highlights the importance of scheduled maintenance.

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Major Industrial Chiller Maintenance 

On a recent Major maintenance visit, the scheduled oil change was carried out. The required oil being selected by our oil analysis process to the correct viscosity for a Grasso reciprocating compressor operating at a 1° saturation.

Oil Drain Out During Industrial Chiller Maintenance

The compressor was valved off from the rest of the system. The standing pressure of the vapour in the vessel was 5.8 bar. On the bottom of the sump is located an oil drain port, this is because it is the lowest part of the system. Using hoses and a valve, the oil was drained into empty oil drums.

Oil Pump In during Industrial Chiller Maintenance

Our engineer removed the old oil for recycling, then lifted the new oil to the work location. He used his portable oil pump to pump the oil back in using the same port from which the oil was drained. The oil came to the correct level on the oil sight glass and the vapour was bled from the oil filter so that the compressor was primed with oil. When the system starts, the oil pump pushes the oil through to the cylinders of the compressor.

Industrial Chiller Maintenance Monitoring

The oil heater was switched on until the oil was 46°. The chiller was then started and run tested. The Delta P across the oil filter was found to be nominal at 0.5 bar. The oil level remained at the correct level as the three way valve opened to the oil cooler. The oil cooler, in turn being cooled by a cooling loop which uses some of the tubes on the air cooled condenser.

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Industrial Chiller Maintenance and the MAXIMUS ADVANTAGE™

Any Chiller

We work on all kinds of chillers from the smallest Italian process chillers, through to large air cooled chillers and centrifugal chillers used for industry.

Any Problem

Problems are our bread and butter- that’s what we do best! Whether you require centrifugal compressor remanufacturing, or the system drying out after a burst heat exchanger- it’s all in a day’s work.

Any Part

We have an excellent supply chain where we pride ourselves on sourcing any part for your chiller. Where a part is no longer manufactured or is not available- we fit a different part. A chiller is just a chiller at the end of the day- we can achieve the same or better design characteristics and efficiency with a different part.

Any Refrigerant

HFC refrigerants are being phased down but are still the most popular variety. They are being superseded by HFO refrigerants which will become more popular over the coming years. We are also adept in the handling of natural refrigerants, such as, ammonia, propane and carbon dioxide.

Anywhere

When you do something as niche as what we do- you cannot expect to just work outside your back door. With blue chip customers around the UK and around the world- nowhere is too far for Maximus Chillers.

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To read more about coefficient of performance hit the Tag at the top of the page.

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Green Bitzer compressor being vacuumed during HFC chiller service

HFC Chiller Service

The HFC chiller being serviced in the photo is 600kw. It consists of two systems with a large Bitzer compressor for each system. It has a bespoke Micro Control System front end to run the machine and stop it should there be a fault condition. The chiller had been reported by the customer to have tripped out on a low pressure fault.

HFC Chiller Diagnosis Service

The readings of superheat and subcooling are available in the controller. This removes the need to fit instrumentation carried by our engineers. The process of diagnosis was therefore speeded up. The result being that the chiller was found to be running short of refrigerant.

Return Visit to Decant the Refrigerant

A Quote was submitted to the customer for approval. Once the Order was raised, a convenient time was arranged to return to site and carry out the service visit. The remaining charge of refrigerant was decanted into our recovery vessels with one of our fast pump out units which are carried by each of our engineers.

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Looking Around the Pipework for a Leak

Nitrogen, an inert gas, was introduced into the system to assist in the location of the leak. The leak was quickly found on one of the end turns of the condenser.

Brazing and Pressure Testing

Our engineer made good the leak using his brazing torch. Then, the integrity of the system was proven to industry standards with a system pressure test.

The Evacuation Process for HFC Chiller Service

The picture shows a 10 cfm (cubic feet per minute) vacuum pump being used to dehydrate the system during the visit. Each of our engineers carries a vacuum pump of this capacity as it speeds up the process. One refrigerant hose being fitted to the discharge pipe and another, smaller hose being fitted to the suction pipe. The system being vacuumed to a deep vacuum.

Recharge and Run Testing

After the chiller had been recharged with some of the charge of the refrigerant R134a, the remaining refrigerant was charged in its liquid phase, away from the compressor, until the superheat and subcooling values were within industry limits. A large amount of load was available as the chiller feeds an air blown film plastic manufacturing facility.

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Engineer carrying out process chiller service with yellow and black cylinder

Process Chiller Service

Maximus Chillers has just carried out process chiller service to a flooded evaporator. The refrigerant seal on a four bolt, flanged coupling had been found to be leaking liquid refrigerant. There was no possibility to valve off that section of the machine, as the flooded evaporator is the storage vessel for all of the charge of the system in its liquid phase.

Refrigerant Decant for Process Chiller Service

Our high capacity pump out unit was set up next to the machine to carry out the task. 55 kg of refrigerant was recovered in a short time into our recovery cylinder. This refrigerant was collected for recycling after the job was completed.

Process Chiller Refrigerant Leak Service

The flanged coupling was unbolted and the failed refrigerant seal was removed. The new seal was fitted from our full range of sizes that we keep on the shelf in our stores. Our engineer bolted the flanged coupling back up to the correct torque setting.

Pressure Leak Test

A nitrogen pressure leak test was carried out to ensure the integrity of the system with the result being a pass.

Dehydration Process

As the system was open to atmosphere, air had got into the system which carries moisture content. The moisture and non condensables were removed down to a near perfect vacuum using one of our high capacity vacuum pumps.

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Charging of Refrigerant

The photo shows the charging of a cylinder of refrigerant into the system in its liquid phase. The cylinder has a dip tube fitted for ease of handling. Once the pressure in the system and the cylinder equalized, remaining refrigerant was drawn into the system during the operation of the plant.

Run Testing

The sight glasses and level glasses were found to be at the optimum level under the normal running conditions of the process chiller. As it is a flooded system, there was found to be a low superheat value. A high subcooling value was achieved with the use of a subcooler. Our engineer monitored a full cycle of an hour and a half: compressor temperatures and oil level were found to be within normal operating limits.

Remote Service Monitoring of Process Chiller

The process chiller can be remotely monitored via a data uplink through the internet. Our office continued to monitor the plant for some days as it went into seamless operation.

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Two dark green centrifugal chillers undergoing maintenance in plant room

Centrifugal Chiller Maintenance

At the beginning of the year we completed centrifugal chiller maintenance for one of our customers in America. A last overseas trip for the moment given the current world lockdown. The chillers in the photo chill water that is pumped around a university campus.

Centrifugal Chiller Maintenance of Redundant System

The plant has a water cooling shell and tube evaporator and a water cooled shell and tube condenser. It has been designed according to the N+1 principle: N being the amount of cooling required and 1 being that same amount of cooling again. Each chiller has enough capacity to satisfy demand. Given the large size of the campus, this principle was critical to keeping the University functioning should system failure occur. The chiller on the right was the lead chiller on arrival. After taking detailed readings during the maintenance, our engineer switched that chiller over into being the lag chiller and took readings from the chiller on the left. He rotates the lead/ lag of the chillers on each visit to balance the run hours of the compressors.

Volumetric Efficiency

Centrifugal chillers have a lower volumetric efficiency compared with positive displacement compressors such as screws and repips. This is because the impeller does not mechanically compress the refrigerant like a piston in a reciprocating compressor. This kind of compressor relies on centrifugal force to spin the refrigerant off the tip of the impeller and onto the next stage. The refrigerant is then discharged from the compressor.

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Mass Flow Rate

The above is more than compensated for with a high mass flow rate. That is to say: a high volume of refrigerant circulates around the system at its operating density. A large capacity machine is cost effective when considering energy efficiency and centrifugal chiller maintenance costs.

Gantry Crane for Centrifugal Chiller Maintenance

The gantry crane in the picture is available to aid with the lift and shift of the compressor, should compressor failure occur. Maximus Chillers are specialists in the overhaul of centrifugal compressors. We can arrange the lift out, transportation, strip down and reassembly of your compressors. All of our strip downs come with a 12 month warranty to give you peace of mind and confidence in our ability.

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R134a chilling plant maintenance showing screw compressor and oil separator with tick sheet and digital thermometer on top

R134a Chilling Plant Maintenance

We recently carried out R134a chilling plant maintenance at our customer’s factory in the North West. The chiller is 600kw with 2 single compressor systems. It has an ‘in house’ controller on it with occasional spurious trip outs. We are working with the problem so far, but an option if the problem persists is to fit a reliable, cheap, off the shelf controller. The factory requires a process water temperature of 6°. The plant is around the middle of the lifespan and has been properly maintained.

R134a Chilling Plant Maintenance Checks

Unlock Controller

The customer had accidentally locked the controller by pressing the wrong buttons. The machine still functioned as it should, but the customer was unable to modify User settings or look at the readings. Our engineers carry a book with an extensive list of information for any controller which has been built up over time. The procedure was followed to unlock the controller, then the settings were checked.

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R134a Chilling Plant Sensor Maintenance 

The sensors can be offset to compensate for a sensor reading out slightly. No offsets were saved and the sensors all read to within a degree or two of our digital thermometer. Our engineer then checked the sensor locations to ensure they were fitted correctly and insulation had not deteriorated.

Fan speed Controllers and Subcooling

During the R134a chilling plant maintenance, particular attention was paid to the fan speed controllers and the subcooling of the refrigerant. This is because of occasional spurious high pressure trips. All the wiring was tightened and the plugged connections were checked and tested. The controller sends a variable run signal to the fan speed controllers. This is worked out from the analogue input signal from the high pressure transducer. If the problem persists, we will have to look into fitting more reliable head pressure controls.

Compressor Slide Valve

The oil solenoids which push and pull the compressor slide valve were operating correctly. The controller sends volts to the solenoids to control the position of the valve. A slide valve potentiometer sends feedback so the controller can work out the percentage position of the valve.

To read more about chilling plant maintenance click the Tag at the top of the page.

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Air cooled chiller planned maintenance showing both economizers with solenoid valves and expansion valves

Air Cooled Chiller Planned Maintenance

An air cooled chiller planned maintenance visit for a long standing customer of ours. They have just signed up to another 3 year contract. We know at Maximus Chillers that if we want to keep our customers, we must continue to offer the Maximus Service. Maximus is Latin for the highest and the greatest.

Critical Air Cooled Chiller Planned Maintenance

Planned maintenance is essential for these chillers as they are critical plant. They feed a large conference room which is a major part of the end user’s business. They can’t afford to loose the conference room when there is an event on. There is redundancy in the plant, but the customer always makes sure that the issues highlighted on the planned maintenance are acted on promptly. Also, the chillers feed a water cooled condenser for a pack which cools £50,000 of products used during the conferences.

Air Cooled Chiller Oil Planned Maintenance

There is 1mw of cooling across the 2 chillers. Our engineer noticed that the oil level was slightly below the sight glass on one of the 250kw Bitzer compressors. The machine had previously been extensively run tested to ensure no oil return issues were present. Therefore, he decided to adjust the level with the oil available onsite.

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Economizer

The economizers, in the picture, were tested to ensure the solenoids were opening when the program sent the run signal. The electronic expansion valves functioned correctly and subcooled the liquid further after the condenser.

Head Pressure Control

The head pressure control was functioning correctly, keeping a steady 8 bar of pressure across all stages of loading and water system temperatures. This is because these chillers use a fan speed controller for each system. The fans cut in at the minimum running speed, which prevents stalling and over heating. Also, all fans running together are more reliable. Fans fail on systems using relays or pressure switches as the higher pressure fans don’t often come on. When they do, moisture has ingressed into them causing them to fail.

To read more about air cooled chiller maintenance click the Tag at the top of the page.

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Follow this link to read more | Carel cut phase speed controllers


Yellow oil drums, ammonia refrigerant cylinders and flammable flushing agent of chiller parts supplier

Chiller Refurbishment Supplier

Maximus Chillers is an established chiller refurbishment supplier. Maximus means the highest and the greatest in Latin, so we pride ourselves in offering the highest and the greatest customer service and technical capability. There is never a job too big for Maximus Chillers- we are seasoned in following a problem through to the logical solution.

Chiller Refurbishment Parts Supplier

Any part is available to our contract customers. We have a worldwide supply chain of the best suppliers. This means any part or refrigerant can be sourced at your convenience. When a part is not available, a different part of the same design specifications is selected and usually delivered same day. By same day we mean: the part is loaded into a van- then and there- and driven to site!

Oil and Refrigerant

We keep a stock of oil, refrigerant and other materials in our stores- see picture. This provides you with 'round the corner' convenience to your factory or facility. Whatever kind of ammonia grade specialist oil you require- we have it on the shelf. With a comprehensive range of other chemicals and solvents- Maximus Chillers completes the picture.

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Chiller Refurbishment Diagnosis

Our engineers are in their comfort zone while carrying out diagnosis during chiller refurbishment- that is what they do best! Even when a fault involves wiring that disappears into a loom, down the other end of the machine, with no wiring diagram- Maximus Chillers can help. Usually, however, faults are obvious to our engineers or can be found easily.

Technical Support Desk

Our contract customers enjoy the full benefit of our global technical support desk. We offer real time technical support with manuals being sent electronically to site. Where a time difference is involved, we arrange a time convenient to both locations, or answer emails when the office opens in the morning. If we can talk you through over the phone, we can get you up and running with the minimal disruption to your process.

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Visit the ASHRAE for Standards and Guidelines Under Continuous Maintenance


Frost covered blue oil return vessel during the removal of industrial refrigeration sludge

Industrial Refrigeration Sludge

This industrial refrigeration visit is to remove sludge from the system. There had been a long period of neglect prior to Maximus Chillers attending site, so regular oil changes had not been carried out. Two oil changes have now been carried out and still a small amount of sludge still remains in the system.

Industrial Refrigeration Sludge Removal

Due to previous sludge removal, the plant was down to about half of its 60kg charge of refrigerant. It was starting to show signs of refrigerant shortage as the machine was preventing loading up. An ammonia suitable pump out unit was used to decant the remaining refrigerant into a cylinder for disposal.

Pressure and Temperature

Once this had been carried out, any residual refrigerant in the oil and liquid on the low side of the plant was carefully handled until the plant was at the same pressure and temperature of the surrounding environment. See picture of some remaining liquid boiling off in an oil return vessel on the bottom of the flooded evaporator.

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Industrial Refrigeration Sludge Oil

Once the pressure and temperatures equalized, our engineer drained the oil in the system from four different vessels. The oil was then removed from site for recycling. Usually, pressure helps with the process, but as the system was empty, gravity was sufficient for most parts of the plant. Nitrogen being introduced to the oil supply pipe to push it back to the oil separator.

Flushing Agent

A flushing agent specially formulated for use in ammonia systems was used to aid the removal of sludge and oil from the pipework around the chiller.

Evacuation

After a pressure test, the evacuation process was started. This was to boil off any remaining flushing agent, to remove non condensables and remove any moisture. A near perfect vacuum was achieved.

Run up

New refrigeration grade anhydrous ammonia was charged into the system, a little at first to check for any leaks. Then, the plant was checked for effective running conditions. All readings were okay with the compressor loading up to 100% before backing off to match the load.

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Read more about oil analysis and testing at the Institute of Refrigeration | Click Here


Green chiller panel with doors open, showing contactors and PCBs during water chiller maintenance

Water Chiller Maintenance

Maximus chillers provides water chiller maintenance to all kinds of machines. Some of which have kilowatt hour meters fitted. This means we can monitor the reduction in energy consumption, directly as a result of our maintenance being carried out.

Efficient Water Chiller Maintenance

Maintenance is carried out to ensure every aspect of your chiller is running efficiently. We believe our maintenance checklist is the best in the industry. It looks in detail at the running conditions of the plant, component adjustments and the parameters in the controls. The checklist is used to assess if there are problems that are starting to occur before a safety shutdown happens. Below are some of the issues that we keep on top of to increase the efficiency of your plant.

Shell and Tube Insulation

The build up of dirt acts as an insulator in shell and tube heat exchangers. These are used for the evaporation and the condensing of the refrigerant.

The Evaporator

In the evaporator, should the tubes be fouled, there will be a reduction in latent heat absorbed into the system. This will cause the plant to stay on longer and use considerably more energy. Should the tubes become considerably fouled, the chiller will malfunction and eventually system shutdown will occur.

The Condenser

In a shell and tube condenser, the reverse of the above will occur. Tube fouling, acting as an insulator, will prohibit the rejection of heat from the system. The head pressure control will open the condenser controls to try and assist in heat rejection. Heavy fouling will cause an increase in the consumption of energy. Eventually a safety shutdown will occur causing loss of production.

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Compressor Loading

If the loading of the reciprocating compressors is faulty, the plant will not be able to effectively match the load.

Over Loading

Too much loading may occur, causing the water chillers to achieve set point too quickly. The plant will then go through the off cycle. This means that the plant will have to load back up, using more energy than matching the load continuously.

Under Loading

Should the plant be unable to load up to the required level to match the load, this will cause the water temperature to creep up and the lag chillers being called for to match the load. More water chillers running than necessary dramatically increases energy consumption.

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Visit the Refcom site to read about leak checking during water chiller maintenance | Click Here


Process chiller maintenance of grey Italian chiller with cover removed

Process Chiller Maintenance

Maximus Chillers recently carried out process chiller maintenance to an Italian machine.

Process Chiller Maintenance for Water Level Sensor

The process chiller has a water treatment schedule, but the water level sensor needed maintenance. This is because the three probes of the sensor were not completing continuity. The probes complete the continuity from the wire going into the sensor, along the probe, then to another wire completing continuity back to the controls of the chiller.

Low Water Probe

If the controls loose continuity to the low water probe, the alarm is triggered and a call out is arranged to resolve the issue.

Correct Level Probe

In normal operation, the correct level probe is activated and the chiller runs as normal.

High Water Level Probe

Should the high water level probe be activated, again the alarm is triggered and a call out arranged.

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Process Chiller Maintenance Call Out

As we were already on site to carry out the maintenance, there was no need to arrange a call out. We soaked the sensor for an hour in a special a decontamination chemical that has been designed to restore the probes. That done, the rest of the maintenance was carried out including the tightening of the wiring and motor connectors. It was possible to do this on this visit as the factory was not in production.

Run Testing

All readings around the chiller were taken when the factory went back into production. We found the fridge system to be working with optimum efficiency, meaning that the chiller will use the optimum amount of electricity. Efficiency is a great concern to a factory as they want to reduce their carbon footprint as much as possible.

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Follow this link for the IOR celebration of chiller service engineers Click Here


Chilling plant service showing yellow top recovery cylinder with gauge line and sight glass fitted

Chilling Plant Service

Chilling plant service had been arranged because our customer had been having high pressure problems.

Transducer Required Chilling Plant Service

The 4-20mA transducer needed replacing as it was reading low by a long shot. Therefore, the PLC was not bringing the fans on as it should. The pressure in the high side of the system was getting up to 40 bar. This is because the refrigerant was R410a- it has a higher head pressure than other commonly used HFC refrigerants, such as, R407c. We ordered the replacement transducer which is fitted with a female fitting.

Chilling Plant Service Leaks

Our engineer concentrated his attention on the high side of the system to start with. Then, he found a leak on a fitting, a leak on the pressure relief valve fitting and a leak on the liquid line near the drier. A sealant was used for leaks on the fittings- they were removed, cleaned and refitted. The leak on the liquid line was re sealed by removing the section of pipe, removing any remaining solder, then the section of pipe was rebrazed.

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Pressure Test

The remaining parts of the system were leak tested then the plant was put on a pressure test to ensure the whole system was leak free. The pressure test was satisfactory and so the evacuation process could be started.

Evacuation Process 

Each of our engineers has a powerful vac pump to speed up the dehydration process. This means that a deep vacuum can often be pulled on the same day, instead of the usual overnight process. The nitrogen and other non condensables were removed quickly and the Torr gauge came down to the pressure where moisture was being removed. At this pressure, any moisture is forced to boil off around the system.

Recharging of the Chilling Plant Being Serviced

In the photo, the plant is being recharged at the end of the work. It is being recharged into the liquid side of the evaporator. All readings were okay when running the system and further leak tests were carried out at normal operating pressures.

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Read more about refrigerant reclamation by following this link to Wikipedia | Click Here


A chiller condenser retrofitting lifting operation outside in the compound

R407c Chiller Condenser Retrofitting

We recently undertook the job to carry out bespoke R407c chiller condenser retrofitting in the North West.

Rusted and Corroded Condenser

The old condenser looked alright on the surface- the fins were in good condition. The condenser was 18 years old, however, so when an attempt to repair a leak was carried out- the condenser leaked further along. This is because of the warming of rusted and corroded copper with an oxy-acetylene torch.

R407c Chiller 'V' Condenser Retrofitting

We arrived on site to measure up for the job. The ‘V’ condenser was built to order. We manufactured an exact replica to the same specifications and sizes of the old one. The operating pressures and high pressure cut out limit were taken into account in the design and the use of materials.

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Lift Out of the R407c Chiller Condenser being Retrofitted

On the day of the lift and shift we isolated the panel and checked it was dead, then we removed the panel and laid it on it’s front. This was to access the rivets behind the panel. These rivets, the ones on the other end of the chiller and around the lid were removed using a tool. The fans were disconnected and removed to make the lid lighter to lift off. Then, we attached slings to the chiller condenser and lifted both halves of the 'V' out.

Lift In

This part we did not want to get wrong as the condenser was brand new and did not have a mark on it. A reverse of the removal- it fitted perfectly just the same as the old one. With the lid lifted back on and the fans in- time for brazing then the pressure test.

Pressure Test, Dehydration and Recharge

The pressure test was satisfactory so our engineer put the system on vac for dehydration purposes and the removal of non condensables. After a deep vacuum was achieved the system was recharged and run tested. No issues were found.

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Ammonia refrigerant cylinder being winched up a cat ladder using a block and tackle

Industrial Refrigeration Ammonia

The industrial refrigeration ammonia visit was in Aberystwyth. We look after 2 ammonia chillers on site. They are 10 year old chillers that have been designed to need ongoing attention. Quite easy job as the faults they go into are reoccurring round in a circle. They have previously had the same problems.

Ammonia Shaft Seal for Industrial Refrigeration

The shaft seal had started to leak ammonia. It was replaced by removing the shaft seal cover, splitting the coupling and sliding the shaft seal over the shaft. After removing the non condensables, we reintroduced the ammonia back into the compressor. The 'o' rings leaked.

Leaking Industrial Refrigeration Ammonia 'O' Rings

Leaks on ‘o’ rings occur because they become flattened and plastic like. This is caused by heat around the high side of the screw compressor. When there is pressure in the system- the oil if forced against the gap- making a seal. After the ammonia refrigerant had been handled- the oil ran away- causing the leak when the ammonia was reintroduced.

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Lift and Shift Visit

The pipework and ancillaries had been removed from the compressor prior to the visit. Our lift and shift guys arrived and set up their lifting equipment. They raised the compressor and manoeuvred it on across the roof. They then manoeuvred it up then down some steps. They used lifting equipment to get the compressor, end on- down a cat ladder.

Compressor Strip Down

It is always better to strip down this kind of compressor in a workshop- on a bench with compressed air and all the tools nearby. We unbolted the castings and slid the screw out. The various castings being laid out in a line. We replaced the ‘o’ rings for new the rebuilt the compressor.

Industrial refrigeration ammonia being charged by an engineer wearing breathing apparatus and gloves
Ammonia refrigerant being sucked into the low side of a flooded evaporator

Ammonia Refrigerant Charge

Part of the ammonia refrigerant had been handled during the visit. This left the compressor pipework, compressor and the oil separator open to atmosphere. The non condensables were evacuated. In the photo we are lifting the cylinder up a cat ladder into the plant room. From there it needed to be man handled up some steps, down some steps and out onto the roof. We charged the ammonia plant with liquid ammonia until the superheat and subcooling values were within industry known limits. The sight glass levels and condition were monitored too.

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Chilled water system repair of condenser to a silver chiller with blue compressors

Chilled Water System Condenser Repair

Chilled Water System Condenser Beyond Repair

The repair of the condenser was required on this chilled water system because the previous company had been chasing leaks round in a circle. Therefore, the customer had decided to buy a new condenser. This was our first job with a new Contract, so we wanted to make a good impression.

Condenser Removal

There was no refrigerant in the system so our engineer cut the discharge and liquid line to the condenser. He then removed the rivets so the frame could be taken apart. Lifting equipment was fitted to the old condenser to aid the removal. Then, slings were fitted and a forklift truck removed the old condenser.

Condenser Replacement

Our engineer supervised the condenser replacement. He found that the new condenser did not fit correctly. The new condenser was 5mm thicker than the old one. It was decided to lift it back out and angle grind the frame to make more room. Once this was completed, the new condenser fitted correctly and was bolted in place.

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Pipework Repair

The pipework had to be repaired and brazed in. Then, the standard practice of a pressure test to ensure the integrity of the system.

The Evacuation Process

Having passed the pressure test, our engineer set up the vac pump and started the evacuation process. This is to dehydrate the system by pulling a vacuum of less than 2 Torr. Any moisture in the system will boil away and leave the system dry.

Recharge and Test Operation

The refrigerant is R410a. Our engineer put around half the charge in, then trimmed the remaining charge according to the superheat and subcooling values. He monitored the system for the rest of the day- looking for leaks as the plant was at operating pressures of 30 Bar. All was well, so the customer signed off the paperwork as he was pleased with the capability of our engineer.

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Global chilled water system service near Saint Basil's Cathedral

Global Chilled Water System Service

Moscow Visit

Always good for our engineers to get out of the country to carry out global chilled water system service. He just had a little free time this visit to see Red Square and Saint Basil's Cathedral. Most of the visit was bogged down resolving issues.

Electrical Problems

One of the chillers was pumping down due to electrical problems. One of the solenoids for the evaporator was not opening. All checked out okay with the solenoid coil and valve. Following the wiring diagram lead to the relay board. The relay board is responsible to run various components around the compressor. It was not obviously blown and there were no dry soldered joints on the back. Our engineer decided to tighten up the wiring and unplug, then plug all the connectors back in. When he ran the chiller again the problem went away.

Chilled Water System Global Service

As we provide a global service: we cannot get back the day after leaving site. Therefore, after resolving the above issue, our engineer ran the system in local with some of the other systems off to prove it. All was okay. After completing the rest of the service on the chillers, he put the whole of the plant back in Auto to prove it all together.

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Flow Switch Failure During Global Chilled Water System Service

Due to security issues, this one of the most remote plant rooms for a flow switch to fail. The chiller did not stop when a test was carried out. Our engineer didn't want to valve off the water system as the air handlers are old and 'dead heading' could cause failure. Instead he decided to use the Hand/ Off/ Auto switch for the pump. After several attempts of trimming he got the switch to settle down, then carried out tests to make sure it would not happen again.

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Chilled water system maintenance showing flow switch at 0 reading

Chilled Water System Maintenance

Maintenance of the Chilled Water System Flow Switch

The chilled water system flow switch requires regular maintenance due to a to build up of contaminants on the sensor. Over time, slime accumulates giving false readings. The problem is relatively easy to sort out: a wipe with a cloth.

Retrieving the sensor

The more difficult part is retrieving the sensor. It is fixed with a bolt into the water system. Therefore, there is pressure inside the water system. This pressure is handled and the glycol drained into vessels.

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Checking the Fault Out Level

As you can see from the picture: there is a green light on 0. This indicates that the pump is off, not to be confused with pressure. With the pump on: the green lights go all the way up to 9 with the fault out level showing red on 7. Flickering between the numbers indicates that the flow rate is starting to drop off.

Maintaining the Chilled Water System Fault Out Level

Using a terminal driver and the manual that comes with the flow switch: the buttons can pressed a number of times to 'self test' Also, the fault out level can be set.

Testing the Flow Switch

The flow switch is manually tested using one of two methods. This ensures that the switch will function correctly when it needs to.

Maximus Chillers offers the whole package for the maintenance of your plant. With state of the art equipment and the best engineers- we complete the picture. Weather you have a small problem like the above mentioned flow switch, or a big problem like compressor failure- Maximus Chillers can help.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Read more about flow measurement on Wikipedia.


Mirror looking for leak during chilled water system eev service

Chilled Water System EEV Service

Chilled water system EEV service was being carried out because the mechanical parts had failed. This particular valve is prone to this fault. It is an OEM electronic expansion valve, so our technician found the voltage for the motor and found a similar part with the same amount of steps.

The EEV driver was found to be functioning satisfactorily. Sometimes, depending on how the mechanical part of the EEV has failed, the driver can be overloaded and burned out.

Electronic Component Refurbishment

Where electronic parts, such as the EEV driver, are found to be burned out- Maximus Chillers has a refurbishment laboratory at head office. We have the capability to strip down the component and fault find where it has blown. Usually it is quite simple: the jammed mechanical part of the electronic expansion valve has burned out the power control on the driver for example. More complex fault finding and component replacement on the circuit board can be carried out also. Another option is to replace the driver with a like for like swap or retrofit to a different driver.

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Pump Down for Chilled Water System EEV Service

The chiller was pumped down and valved off. This saves on the time and recovery vessel to pump the refrigerant out.

Remove and Replace

Once pumped down, our engineer removed and replaced the valve, sealing it on its knife edge seal. The wire was passed up the conduit and into the panel. The wiring colour scheme was different on the new valve, so some time was taken to ensure it was wired up correctly.

Open it up and Switch it on

After leak testing, the refrigerant system valves were opened back up and the plant switched back on. The correct superheat and subcooling values were achieved concluding a successful visit.

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To read the Institute of Refrigeration guide to expansion valves Click Here


Industrial refrigeration oil change showing ammonia warning sign

Industrial Refrigeration Oil

An industrial refrigeration oil visit was arranged because of an oil return issue. Several fans had been down on the air cooled system. This causes the system to unload so as to prevent a fault occurring. The lower mass flow rate of the refrigerant caused oil to migrate to the low side of the system. Several vessels are available with various forms oil return control. These vessels were valved off. A two man team with the correct ammonia PPE and breathing apparatus carried out the job.

Not Enough Oil Recovered from the Industrial Refrigeration Plant

Only some of the oil was recovered from the plant. Therefore, the engineers decided to add new oil to get the system running. The only problem with doing this is that once running the machine, the oil has to be got back out. Therefore, the oil had to be adjusted a second time to resolve the oil return issue.

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Fan Decks

For this visit, scaffolding had been erected in accordance with the Risk Assessment. The old fan decks were lifted out by the two man team. A really good team was sent out: one of the men was more technical and the other more mechanical- complementing each other with their different skill sets. The new fans were an updated version and the wiring was different. The fault link had to be adapted but the 0-10v input from the controller was the same. The controller reads the pressure from a transducer, then sends out a voltage which the fan turns into the corresponding speed.

System Testing

The fault link had been correctly modified, so the testing of the system was carried out. The machine loaded up to 62% and monitoring continued during the rest of the visit.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Water chiller service of evaporator showing lagging removed and blue compressor

Water Chiller Service of Evaporator

Not often does a water chiller service of evaporator fault occur. The evaporator can freeze up and burst the tubes inside the shell. This fault involved the shell itself bursting. On close inspection- the shell was made out of thin steel- not the usual heavy rolled steel. It looked like the near end on the photo had sagged down, causing the evaporator shell to buckle.

Replacement of Evaporator

This option would be expensive due to the cost of the evaporator. It would be a difficult visit because of access issues. The builders decided to site the water chillers round the back of the building, this makes them very difficult to service. Our lift and shift guys would be needed to get the old chiller evaporator out and the new one in. There is a difficult corner to get round where the evaporator would have to be tilted up to get it round. Also, a fence wound have to be taken down around the chillers. Of course security is an issue but so is access to the chillers.

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Water Chiller Service of Evaporator using Silver Solder

Because of the above, it was decided by the customer that we would fix the leak using silver solder. The Risk Assessment Method Statement allowed for the job to be carried out with a half hour fire watch. The oxy-acetylene lines were leak tested prior to the job. Both leaks were soldered up but despite the evaporator being drained down, there was still water and steam trying to get out. Not the best soldering resulted- but it held.

Water Chiller Service of Evaporator Paintwork

Because the chillers are outside, the paintwork is essential- poor paintwork will reduce it's life. After preparing the surface, specialist paint was applied so as to protect the evaporator for the future.

Lagging

The purpose of lagging is to reduce heat gain from the environment and provide protection from the elements. Therefore, the lagging was reinstated after the job.

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See the Institute of Refrigeration Evaporator Efficiency | Click Here

 


Chiller refurbishment company electronic components in electrical panel

Chiller Refurbishment Company

Choosing a chiller refurbishment company is cost effective because the main cost of a large chiller is mostly in the fixed plant. That is to say: the two main heat exchangers and the compressor. Therefore, this is the most environmentally friendly option as the carbon footprint of building new plant is very high. This is not mentioned when you purchase a new chiller. With chiller controls replacement, this kind of plant can last for 50 years. One of our competitors has been carrying this out to a chiller that dates back to the 1970s and is still in service!

Chiller Evaporator Refurbishment Company

Refurbishment of broken tubes can be performed to beyond manufacturer's recommendations. Larger scale replacement of the tubes can be carried out giving the same lifespan of the original tubes. This is a major overhaul at a fraction of the cost of replacing the chiller.

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Chiller Compressor

We strip the chiller compressor down in our workshop. It is made from heavy castings so will last a very long time. We provide a 12 month warranty on all our chiller compressors. Read More about centrifugal compressor remanufacturing on our web page.

Chiller Controls

State of the art controls can be fitted. The controls that come with the chiller are made 'in house' so they are often prone to spurious trip outs. These trip outs can cause a loss in production. A control panel, designed specifically for that chiller comes ready built. All you have to do, is wire in the various sensors and transducers. The run signal, compressor soft start, remote loading and monitoring can be easily integrated. Simple and easy solutions to big problems are what we do!

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Read more about the chiller controls we fit to existing chillers.


Air cooled chiller maintenance of two white chillers with green compressors

Glycol Chiller Maintenance

Bodger Watch

We carry out glycol chiller maintenance at an office building in the North West. The maintenance sector is usually very good, but this is bodger watch! The customer told us that there had been this guy who used to come who spent most of his time in the canteen- reading manuals on his laptop! Not even the manuals for that site either! You couldn't make it up could you? What kind of a maintenance schedule is that? They said he used to fix everyone's bathrooms in the evening to make up his pay! This is bodger watch!

One of our engineers rang the office from site the other week. He was struggling to carry out the maintenance- the glycol dosing. He was advised to use his testing instrument to assess the level in the water system. He came back with the result- too much glycol. The customer uses propylene even though the site is heavy industrial. This is because the price is narrowing between ethylene and propylene glycol which is not toxic.

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On Site Glycol Chiller Maintenance Engineer

The customer adding glycol is the usual course- it means their onsite engineer can keep on top of things. This onsite engineer was a little too keen though: he had been putting too much in.

Glycol Removal

Our pump out team was sent to site with their tanker and equipment. Then, the correct level of glycol was charged into the system.

Clear Site

Last but not least, our engineer gave the machine a wipe down and the chiller location a sweep- good house husbandry costs nothing.

For the efficient running of your plant- choose Maximus Chillers.

Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere- The MAXIMUS ADVANTAGE™

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Chiller service of fan decks showing 8 fans

Chiller Fan Deck Service

 

Chiller Fan Deck Service- Bodger Watch

Chiller fan deck service is usually very good, but this is bodger watch! A new customer of ours was telling us about this little guy that used to come. He was reported to have been running around like the apprentice- ringing everybody up! Then when help came, it came in the form of this huge big man who proceeded to get stuck in the chiller! You couldn't make it up! This is bodger watch! The customer asked for a professional service from Maximus Chillers.

Repeated Leaks on Condenser

Our engineer found the head pressure control was bringing the fans thumping on and off forwards and backwards. During a visit, the fans were found to be rattling the frame and juddering the chiller into leaks.

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Learning How to Think

Instead of just swapping like for like parts. Our engineers have the capability to think outside the box and make changes to chiller design. All of our engineers attend the Maximus School of Chillers at Head Office in Droylsden, Manchester. Read More on the Chiller Company page.

Fan Speed Controller

On a return visit, we fitted off the shelf fan speed controllers from our stores- one for each system. These fan speed controllers are stand alone- they do not need to be integrated into the existing controls. When the pressure builds up- the fan speed controller speeds the fans up from the minimum (cut in) to the maximum (same volts as the incoming supply)

Chiller Fan Deck Service- Seamless Operation

Now the fan speed controllers are fitted- there are no more leaks. Effective chiller fan deck service. Any chiller can be made to settle down into seamless operation.

Are you a factory manager or facilities manager with recurring leaks on your chillers? Look no further than Maximus Chillers.

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Visit the Institute of Refrigeration to read a paper on the comparison between air cooled condensers and evaporative condensers.


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