Chiller Condensers

Boxed, shell and tube chiller condenser being lifted into a building with a crane

Chiller Condensers

Shell & Tube

The chiller condenser on a 2 MW centrif we look after had deteriorated over a long period of time. We had carried out tube cleaning and noticed that it had been extensively repaired in the past. There were a lot of damaged tubes that had been blanked off. This had reduced the useful surface area for heat exchange to occur. The chiller was experiencing a ‘discharge limiting’ condition which was causing it to back off to 54% capacity.

Air Cooled

Because of the difficulty to remove and replace the condenser from the plant room, the customer had explored the possibility of air cooled condensers. His idea was to fit the discharge and liquid piping up the side of the building and into the plant room. After considering this possibility, we decided to advise him against using air cooled condensers because it would take two, 16 fan ‘V’ types. This would have a footprint too big for the available space. We decided to use a crane to lift out the old condenser, then lift in the new one.

Pump Out

The old condenser was valved off from the rest of the system and the refrigerant was pumped into an 800 kg recovery vessel. This was one of 2 vessels in the plant room that had been there since the chiller was new.

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Lift Out for Chiller Condensers

The pipework was unbolted and the ancillaries removed. When it came to unbolting the condenser, some of the bolts were seized due to a long period of rusting. Some of them came loose by heating them with oxy-acetylene, the others were ground off with an angle grinder. We used a specialist lifting company to shift the condenser from the plant room and out to the lifting bay. They then attached slings to one end, manoeuvred that end of the condenser to the outside of the building, then attached slings to the other end. Rather them than me! Quite a dangerous operation, but it had been assessed when composing their Risk Assessment Method Statement. The condenser was lifted onto the back of an articulated truck and taken to a scrap yard for recycling. There was quite a lot of copper inside- so our customer got quite a good weigh in!

Lift In for Chiller Condensers

The new condenser, in the photo, was kept in its packaging during the lift up, so as to protect it from damage. Once it was in the building and near to the plant room, it was removed from the box and shifted the rest of the way with dollies. There was some difficulty getting it into its final location. This was because the old steelwork had to be cut back with a blow torch to make the new condenser fit. Also, with limited room and no gantry crane, the lifting company had their work cut out to manoeuvre it. Eventually, it was in location and we decided to call it a day.

Adapting the Pipework

This particular condenser was selected because it was similar in dimensions to the old one. The positioning of the refrigerant and water system pipework was similar too. That said, it was not an exact match. We called an industrial plumbing and welding company in to make the changes we needed. They measured up and built adaptors to bolt in between the condenser and the water system pipework. They cut back the new condenser discharge connection and welded a new flange on. This was so it could be bolted onto the existing discharge elbow from the chiller. The liquid pipe connection on the new condenser was in the same location, but came with a different thread. Therefore, this too was cut back and an adaptor fitting was welded into place.

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Ancillaries

The fittings on the new condenser were BSP and the fittings on the chiller were Flare. We carry an extensive range of fittings that go between BSP and Flare. We can go from male to female, female to male, male to male and female to female. We can step up and step down in size too. Using these fittings, we attached the high pressure switch and high pressure transducer. The wires for the liquid and discharge temperature sensors were extended. This was so they could reach the location of the pockets that were built into the new condenser. Then, we used a special heat transfer paste to get a good transmission of heat in between the sensors and the pockets.

F-gas Pressure Test

We then carried out a strength test and a pressure test in accordance with F-gas guidelines. This was witnessed at the beginning and at the end by the customer. A satisfactory outcome was achieved, so on to the next phase of the job…

Dehydration of Chiller Condensers

We needed to dehydrate the system and remove the nitrogen that was used in the pressure test. This is because nitrogen is a non condensable which will affect system performance. Our powerful vacuum pump was set up, then we left it running overnight. A 1.5 Torr vacuum was achieved, which was the same pressure as when the Torr gauge was fitted directly on to the vacuum pump.

Open the Valves and Test

After removing the vacuum pump, the recovered refrigerant was pumped back in, then the discharge and liquid valves were opened back up. Then, our engineer had a good look round for leaks. I know it had just been pressure tested, but we think it’s always a good idea to check again. This done, the water system pumps were started and the water temperature showed at 23°C on the controller. The set point for the chilled water was 6°C so this warm water was helpful as it gave us plenty of load to carry out the testing. The chiller went through a timer and then started up. It loaded steadily up to 100% with no dramatics- splendid!

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Grey centrifugal chiller compressor being maintained

Centrifugal Chiller Compressor Maintenance

Centrifugal chiller compressor maintenance keeps your critical plant up and running and your customers happy. The work can be scheduled to be carried out during factory shutdown, so as not to disrupt your production. We can also carry out this work to your compressors while the factory is in production. This is achieved by isolating the compressor that needs to be worked on when it is in an off cycle. The compressors on remaining machines can carry on running.

Tasks during Centrifugal Chiller Compressor Maintenance

Here are some of the tasks that we carry out…

Oil Changes

The oil becomes dirty over time by picking up contaminants that have formed in the system. Two of these contaminants are…

Acid

Compressor discharge is the hottest part of the refrigerant cycle. Acid can be formed from the refrigerant in this part of the system.

Refrigerant Types

A popular refrigerant for centrifs is R134a. Because it consists only of one kind of refrigerant, it does not fractionalise into different component refrigerants. This would be no good for a flooded system because one or more of the refrigerants would end up in the bottom of the evaporator and condenser. The remaining refrigerant would circulate and the whole plant would not function as it should. Refrigerants popular for other kinds of system are zeotropic HFC refrigerants. This means that the different component refrigerants have different boiling points- R407c is a good example.

Metal

White metal from the compressor and copper from the heat exchangers end up in the oil. They will eventually be caught by the system oil filters…

Oil Filter Change

After completing the above, now is a good time to change the filter as the compressor is valved off and has been broken into. It is also when an oil sample is taken depending on the schedule…

Oil Samples during Centrifugal Chiller Compressor Maintenance

Our oil samples are transported using our specialist kits which include the bottles and labels. This saves mix ups in our laboratory during the analysis.

Leak Rectification

The drawback of carrying out the above are leaks because the pressure has been pumped out of the compressor into another part of the system. The ‘o’ rings and shaft seal can now leak, this kind of failure can be rectified whilst still on site by the knowledge of our engineers.

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Oil Pre Lubrication

When the compressor starts, the oil pressure is built up first using an oil pump. This is so the internal components such as the high and low speed shaft are properly oiled before they start to rotate. They can run at 10,000 RPM and are very expensive to replace. Therefore, we check the oil pressure gauges and the system controls to ensure optimum ‘pre lubing’ of your compressors.

Volumetric Efficiency

The ratio between the volume actually compressed and the theoretical volume derived from compressor design calculations. This kind of compressor has a lower volumetric efficiency than positive displacement compressors. It is because the refrigerant is compressed off the tip of the rotating impellor or impellors. The refrigerant moves outwards in a circular path due to centrifugal force. A centrif more than makes up for this lower volumetric efficiency by the high mass and volume of the refrigerant that it circulates around the system.

Design 

The refrigerant is sucked from the evaporator into the centre of the impellor which is a disc of radial blades positioned to direct the refrigerant outwards. Due to the low differential of pressure, multiple stages of impellors are often arranged in series with the discharge being directed onto the suction of the next impellor. This is simple in design with less moving parts than some other compressor types. Modern centrifs can have magnetic, levitating bearings and so remove the need for oil in the system altogether. The faster the speed, the better the efficiency- so high speed rotation of the impellor is achieved at full load. The compressed refrigerant is discharged into the condenser.

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Electric Drive Centrifugal Chiller Compressor Maintenance

Most modern centrifs are driven by variable speed drives. This is for efficiency as the load can be exactly matched. Another reason for this is to soft start the compressor. 415v and 3.3kv are popular volt inputs, although other voltages can be made available by the onsite transformer.

Open

An open drive electric motor is the most popular design. It has the drawback, however, of needing a shaft seal which needs to be replaced at periodic intervals. This shaft seal is also prone to leaking refrigerant and oil.

Semi Hermetic

The photo is of a semi hermetic design of this compressor type. The motor is contained inside the suction housing and so has the benefit of being cooled by the refrigerant. No shaft seal is needed and therefore it has none of the associated maintenance drawbacks.

Steam Drive Centrifugal Chiller Compressor Maintenance

On oil rigs there can be an abundant supply of steam that can be used to drive the compressor. It is often used on multi stage compressors which are used for the liquefaction of natural gas. The steam goes through a turbine which is connected to a shaft- this drives the impellors. The steam flow and pressure can be tested and adjusted during the visit.

Woops Something Went Wrong

When you suffer a centrifugal compressor failure- don’t worry. You are in safe hands with the team here at Maximus Chillers. We have a team who can get the compressor out and lift it to the workshop on site, or transport it to our Head Office. We have another team who are experts in the remanufacturing of this kind of compressor. A fast supply chain is in place for delivery of the internal moving parts, gaskets and bearings. We are so confident that you will be happy with us- we offer a 12 month warranty on all of our compressor rebuilds.

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Open chiller controls panel showing PLC, relays, contactors and wiring

Chiller Controls

Chiller controls can be remotely operated and monitored, but in this article, we will be looking at chillers operating in local.

Each chiller has a panel where the lead or the lag chiller can be switched from. They have N+1 redundancy built in, so one of two chillers will normally be in standby with the other one running. The chillers in the photo are equipped with kilowatt hour meters because the customer wants to monitor their efficiency. He has targets to meet and wants to gauge the effect that our maintenance has in reducing his energy costs.

Condenser Pressure

The condenser pressure control is external and stand alone from the panel.

Transducer

A transducer is fitted to the discharge pipe near to the compressor. This gives a 0 to 5vdc control signal to the fan speed controller which is bolted to the frame. There is a minimum and a maximum value on the transducer, so the FSC is programmed to work out the pressure from the voltage.

Fan Speed Controller

415v on three phases are the input to the FSC. It uses solid state thyristors to regulate the output to the fans. This is according to the demand received by the transducer. Solid state means that all the parts are electronic with no moving parts. Fan speed controllers are really good at extending the life of the fans. This is because all of the fans operate together- smoothly and reliably.

Chiller Controls Digital Inputs

There are three essential digital inputs to the controls of any chiller. All of them have a volt signal out to them, which returns back to the panel. If there is a fault- the volts drop out.

LP Switch

This protects the chiller from a low pressure condition. Compressor and evaporator failure would result, so this device is set below the running pressure of the system, but high enough to offer protection.

HP Switch

If the head pressure control mentioned above were to fail, this device would save the chiller from damage from excessive pressure in the system. Components or the pressure relief valve can blow causing a catastrophic refrigerant leak.

Flow Switch

This device detects a lack of flow in the water system. Serious system failure would result if this part is not maintained properly. It needs to be periodically tested and adjusted at regular intervals.

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Chiller Controls Analogue Inputs

The essential analogue inputs on a chiller are the Water In and the Water Out sensors. These are usually NTC (negative temperature coefficient) that is to say: if you hold one in between your fingers and warm it up- the resistance will start to drop off. They usually read in kilo ohms which can be read on a standard multi meter. The program looks at these two sensors and using an algorithm, it calculates the loading requirement of the compressor. They can read incorrectly, so a sensor offset function is available in the software for adjustment. This is just one of the many checks and procedures that we carry out during our maintenance visit.

Chiller Controls Relays

In the photo you can see wires from the various devices around the chiller, wired into a row of relays. These, in turn, are wired into the white relay board at the top. This relay board has several expansion boards linked into it which are held together with an electrical ribbon. Next, the relay board is wired into the PLC... 

Chiller Controls PLC

The reason for these steps in between a device and the PLC is for protection. Sensitive electrical components can be blown due to an earth shortage. At each stage there is a volt drop from 240v to 24v and then to 5vdc.The programmable logic controller is the nerve centre of the chiller. This is where all the inputs go to and where all the digital outputs are sent from. The controller on this chiller is Beijer Electronics- it comes blank from the factory. User keys to operate the chiller are positioned below the display. It can be programmed to run most chillers and indeed it is often seen in factories running anything. A laptop plugs into it and the software for the chiller is uploaded. On one visit, we found a fault with this controller. We bubble wrapped it and took it to our electronics laboratory at Head Office. The issue was easy to resolve- it was just dust tracking across the back of the PCB and so corrupting the program.

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Chiller Controls Digital Outputs

The main digital outputs on this chiller are:

Compressor Run Signal

240v is sent to the compressor starter contactors. There are three: Star (lower amps for a soft start) then a timer switches over to Delta (higher amps for a more powerful running of the compressor) On the other end of the compressor windings is the Line contactor. This contactor runs with both the Star and the Delta contactors.

Float Valve

This is a camber where the level of refrigerant which is coming in from the condenser is detected. The level is transmitted to the PLC, where the program sends a signal to the expansion valve. It opens to the correct degree according to the load on the chiller.

Slide Valve

The compressor can run at 0% with the slide valve shut. When load is sensed from the Water In and Water Out sensors by the controller- the slide valve opens up. The position of the slide valve is detected by a potentiometer. This is calibrated from a minimum to a maximum position. The signal is 4-20 mA which the controller translates into the position of the slide valve.

MAXIMUS ADVANTAGE™

Whatever the problem with the controls, we can find a solution to resolve it. With years of industry experience and a fast supply chain, we offer a service that is second to none. Being able to retrofit is part of what we call the MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere.

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Large chiller, refrigerant cylinder, brazing equipment and tools during chiller service company visit

Chiller Service Company Visit

A typical rainy day in the North West, perfect for a chiller service company visit.

News Article No.11

Electrical Faults during Chiller Service Company Visit

This was a return visit to do a refrigerant leak, but the customer alerted our engineer’s attention to an electrical fault. System 2 was found to be locked out in fault on the recent maintenance visit, but now System 1 was being held off too. The fault message on the controller was High Pressure. The controller sends a 240v fault feedback signal, through the high pressure switch which returns to the controller. Our engineer had a look at the wiring diagram to find the number on the terminal strip and checked it out with his multimeter. As he suspected, there were volts going out, but not coming back. He removed the side panel for system 1 and found the switch on the discharge pipe. It was the type that has a red button on the top. When he pressed it, there was a click and volts returned to the controller.

Alarm Reset during Chiller Company Service Visit

He interrogated the Carel controller and followed the reset procedure. The controls went through a timer and then the start sequence was initiated.

Run Testing during Chiller Company Service Visit

After the first scroll compressor started, the head pressure started to build up, but the condenser fans did not start. The on board high pressure gauge carried on rising until the high pressure switch was tripped again.

Head Pressure Control

A transducer on the discharge is used by the controller to sense the pressure in the condenser. When our engineer looked for this in the controller, it was found to be reading wrong by a considerable amount. There is a facility to enter a password and recalibrate the transducer, but this only allows for a small adjustment.

Test Instrument

Our engineers carry various kinds of test instruments which can be used to give a temporary false reading to the controller. This gets the customer up and running and back in production whilst a new transducer is ordered and sent to site.

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Chiller Company Service Low Pressure Visit

Now on with the job to resolve the low pressure issue with the chiller.

Refrigerant Pump Out

Our engineer lifted the liquid line solenoid valve and decanted the remaining refrigerant into a vessel using his recovery unit. He only got out 7kg of a charge of 36kg.

Leak Testing during Chiller Company Service Visit

We use nitrogen for the leak testing as it is an inert gas that will not cause problems with the refrigerant system. There was a sign of the leak in between the steel frame at the middle of the condenser and the condenser tubes. We always strip the chiller down and leak test the entire system though. This is so that the job does not end up going round in circles. At first the leak could not be found, so the pressure was built up in stages, taking into account industry recommended guidelines for a chiller. Sure enough the leak was where it was suspected to be. The occurrence of this kind of leak can be reduced with the use of vibration eliminators.

Brazing during Chiller Company Service Visit

The location of the leak was reported to the maintenance engineer onsite and a hot work permit obtained. The equipment we use is tested at regular intervals to be safe and in good working order. A half hour fire watch was stipulated in the permit, along with the removal of combustible materials from the work location. Correct PPE being donned, he brazed the leak to the required industry standards.

F-gas Pressure Test

A chiller has a different pressure test procedure to other systems, so our engineer built the pressure up according to industry standards, then recorded it on his pressure test certificate. After the required time had elapsed, he rechecked the readings which were found to be satisfactory.

Vac Pump

Each of our engineers carries a state of the art 10 cfm vacuum pump to speed up the dehydration process. We use high quality Torr gauges too, so as to get an accurate pressure reading. A good read back was achieved at the end of the process.

Recharge and Run Test

After the refrigerant recharge was carried out, a satisfactory run test was achieved.

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Refrigerant Economizers

This particular chiller uses an economizer to further subcool the refrigerant. Chiller designers have worked out that the end user can save a considerable amount of money over 10 years if these components are used. After the subcooled liquid refrigerant leaves the condenser, it goes through a plate heat exchanger. Some of this refrigerant, however, is diverted through a thermostatic expansion valve, to the other side of this plate heat exchanger. Further subcooling occurring through the plates.

Expansion Valve

The refrigerant drops in pressure as it goes through the expansion valve. A bulb is fitted to the suction pipe on the outlet of the heat exchanger. The bulb has to be at the correct 'o clock position as oil insulation will affect the operation of the valve. A capillary tube connects the bulb to the valve. Inside the bulb, the same kind of refrigerant that is running in the system is present in its liquid state. As the temperature rises in the suction pipe, this refrigerant boils off, adding pressure into the capillary tube. This added pressure forces the power element down on the valve body and a needle forces the valve open.

Flash Gas

Imagine if the refrigerant was not subcooled at all. It would be around its saturation point with a lot of it flashing off into its vapour phase. Not good when you have warm water coming back from the process. The refrigerant would not absorb very much latent heat into the refrigerant system.

Efficiency

Imagine, on the other hand, the economizer which is fitted to this chiller. Now we have a good proportion of refrigerant in its liquid phase, on the low side of the system, with a minimum amount of flash gas. The warm process water has more chance to cool and the refrigerant absorbs a lot more latent heat. The chiller achieves set point easier and therefore saves a considerable amount of electricity. With this further subcooling monitored for a while, time for a signature from the customer and another job well done!

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Oil return solenoid removed during industrial chiller service

Industrial Chiller Service

On an industrial chiller service visit, the ammonia alarm was found to have been triggered.

News Article No.10

Industrial Chiller Service Faults

The onsite engineer had fault found the chiller and silenced the alarm, the yellow light was still flashing. The red light was lit on the panel and the red LED was illuminated on the ammonia alarm console. He had reported a smell of ammonia to us over the phone. This gave us a priority of getting to site, as many other alarms of this nature are often spurious. Our engineer attended site within an hour and confirmed that the fault finding was correct as described by the onsite engineer. The chiller is containerized in design as it is situated outside. All around the chiller are door panels for access to the various system components.

Breathing Apparatus and PPE

He donned his mask and full length ammonia resistant PPE before opening one of the panel doors. This was to ensure that he did not get overwhelmed by the refrigerant when he opened the door. He started with the door into the storage area of the containerized chiller. A strong blast of ammonia came out in his face- lucky for the PPE!

Localising the Fault

Working his way around the chiller, our engineer found more and more hazardous door openings! Eventually he found the culprit: one of the two flanges were leaking on the oil return solenoid. The refrigerant vapour was coming out in its usual white form. The oil return pipe feeds off the oil pot which is a chamber that the oil sinks into from the refrigerant economizer. This vessel was valved off and the other end of the pipe valved off too.

Pinpointing the Fault

Now that the ammonia refrigerant leak had started to calm down- it was possible to see through the white vapour to exactly which of the flanges was leaking. It was the right one as seen in the picture. It consists of an ‘o’ ring made of ammonia resistant rubber material.

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Industrial Chiller Service in Local

The above mentioned chiller runs in local in a lead/ lag configuration with the adjacent chiller. That is to say- there is no wire or modem to a remote location. A panel is available in between the two chillers to sequence the switch over between the two. When the chiller tripped out due to the fault, the other chiller was supposed to have been enabled. This did not happen, so our engineer investigated the situation. The sequencer panel sends out a 24v fault feedback signal to each chiller. This, in turn, goes through a relay and back to the sequencer panel if all is good. When a fault occurs, the volts drop out to the relay in the chiller and a relay drops out in the sequencer. When the relay drops out in the sequencer, a normally closed contact makes and brings a red light on. This was not happening, so our engineer followed it through with his multimeter. He found a blown 1 Amp control fuse in the chiller, he replaced it and it blew again. After some careful research he found that there was an earth leakage due to the ingress of water into a safety switch. This switch was nothing to do with the above, but it blew the whole control circuit. Having reinstated the fuse, he found that the panel switched over satisfactorily in local.

Advantages

This kind of operation method has an advantage in its simplicity. There are no complicated BMS systems for the chiller to be integrated into. A sequencer panel is easy to construct and maintain- keeping the costs down to the end user.

Disadvantages

The disadvantage of this kind of system is that the first thing the factory usually notices is that they are loosing the process. The water temperature getting too high is the first alarm signal. With this site, however, there is a permanent onsite engineer on hand. He is experienced with the first checks to carry out and can often get the plant running with no problem.

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Standing Pressure during Industrial Chiller Service

The standing pressure was taken into account on the return visit to fit the oil return solenoid valve seal. Because the valve is on the low side of the system, when the chiller is off, the pressure is higher than when it is on. Therefore, so long as the seal pressure tests to this pressure, then all will be good when the system is running. That is assuming that the valve seals work satisfactorily at a lower temperature range. There are issues sometimes when a seal will be okay at ambient temperature but will leak when it becomes brittle at a colder temperature. This happens usually on an old seal and, indeed, this condition can be tested for when run testing the system.

Leak Testing during Industrial Chiller Service

On fitting the seal, our engineer donned full length ammonia resistant PPE and breathing apparatus. A little at a time, he introduced refrigerant into the area of the valve seal. Any residual air being purged through a valve.

Pressure and Temperature

The standing pressure of refrigerant is affected by temperature. That is to say- that the higher the temperature- the higher the pressure. On the day this job was carried out, the ambient temperature was 12°C and using an app on his phone, he calculated that the pressure should be 5.6bar. This is consistent with Charles’ Law of Constant Volume with a coefficient added for this particular refrigerant. If the pressure had been higher than this, it would indicate the presence of air in the system. Daltons’ Law of Partial Pressures states that all gasses in a vessel will act as if they are on their own, therefore, causing a higher pressure.

Run Testing during Industrial Chiller Service

After the pressure was built up to full standing pressure and the seal held satisfactorily, the system was then run tested to ensure, as stated above, that the seal performed well across the full temperature range during the operation of the plant.

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Mass Flow Rate during Industrial Chiller Service

The mass of refrigerant passing, which is measured by the second.

Suction Density

In this case of the oil return valve seal, we are looking at the density of the low side refrigerant as it passes into the suction port of the compressor. This is shown on the LP gauge near to the compressor. The higher the pressure of the refrigerant, the more refrigerant there is- so it has a higher mass flow rate. This system has a refrigerant saturation point of 1°C which corresponds to a pressure 3.4bar. That is a high mass flow rate for this kind of refrigerant. This is because this refrigerant is usually used in low temperature applications where the pressure of the refrigerant is below that of the atmosphere. In that condition, when a leak occurs on the low side of the system- air leaks in. Air bleed valves are available to remove this unwanted air from the system.

Compressor Loading

The bigger the compressor on a chiller- the higher the mass flow rate. Most compressors have loading solenoids, vanes, or a slide valve to regulate this.

Piston Displacement

Reciprocating compressors use loading solenoids to increase piston displacement. Usually, oil from the oil pump holds the piston valves open and so preventing compression on that cylinder. When more flow rate is needed- the loading solenoid de energizes- the piston valves drop and the cylinder comes into action. Therefore, increasing the mass of refrigerant through the compressor.

Vanes

Vanes are used on centrifugal compressors to increase the flow of refrigerant through the compressor. An actuator linked to a chain is used to open the vanes. The controls work out the correct position of the vanes for a given load condition.

Slide Valve

The slide valve offers a seamless amount of loading, anywhere between 0% and 100% A slide valve potentiometer senses the position of the slide so that the controls can regulate the flow through the compressor. The screw compressor in this article uses a slide valve- on full load with the slide at 100% all readings were taken with a good read back. Another job done- another happy customer!

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Maximus Chillers sign outside our chiller maintenance company office

Chiller Maintenance Company

Diagnosis of Chillers

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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Expansion Valves

We at Maximus Chillers have a comprehensive range of expansion valves, on the shelf, in our stores at Head Office 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. It therefore knows the position of the valve to regulate a close control of 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°C saturation, through medium temperature 0°C saturation, to high temperature 20°C saturation. High temperature applications include laser chillers- the secondary refrigerant cools the oscillator and the laser head.

HFC 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 off 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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Evaporators

Eddy current Inspections by Chiller Maintenance Company

At periodic intervals according to the maintenance schedule, the end plates are taken off the 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 Maximus Chillers.

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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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. On site 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°C 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°C 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 and 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

This is 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°C saturation was normal for that system as defined by the fan speed controller. Now, the system pressure was higher at 28 bar/ 47°C saturation, so our engineer decided to work out the subcooling. A very high reading of subcooling was recorded at 28°C 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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Chiller compressor failure of blue Grasso in enclosure

Chiller Compressors

System Testing for Chiller Compressors

Chiller compressors fail often as a result of ineffective servicing and system testing. 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 and then remedy the problem. Some of the compressor readings we monitor are:

Temperature of Chiller Compressors

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 cooler 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 for Chiller Compressors

Another way of preventing big problems from occurring 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

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°C refrigerant saturation and is used to cool computer rooms. Common causes of compressor failure on this kind of compressor are:

Leaking Castings on Chiller Compressors

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. 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 with 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. The controls operate the loading and unloading solenoid valves to change the position of the slide valve.

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Centrifugal

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 centrifugal 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

These are some issues affecting a scroll compressor:

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.

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

Planned Preventative Chiller Maintenance

Featuring planned preventative chiller maintenance, which is part of a series of longer, in depth 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 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°C high being reduced by 2°C may not calibrate correctly. An amount of trial and error is often required. Also, monitoring the sensor against a digital thermometer at various temperatures is carried out.

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) This includes 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°C 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 has been deteriorating over several 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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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 when you have high water system temperature:

Small Chiller Maintenance Checklist

Low Pressure

If the chiller 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 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 like 'suction limiting' This is the controller preventing the compressor from loading up, so as to prevent a low pressure trip out. 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™

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

Chiller Parts Supplier

Chiller Parts Supplier of Compressors

Centrifugal

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

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

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

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

This type of condenser is used on water cooled chillers. It is protected from contaminants by a strainer on the water system.

Chiller Parts Supplier of Evaporators

Shell and Tube

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™

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

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6 large air cooled chiller condensers maintained with 12 fans each

Air Cooled Chiller Condenser Maintenance

The photo is showing air cooled chiller condenser maintenance being carried out by Maximus Chillers. 6 water cooled chillers are located in the plant room below. They are 750 kw single screw compressors with a control panel located to the side of each. On this visit, the emphasis was to carry out a thorough maintenance of 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°C. Subcooling of 6°C to 8°C 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.

Air Cooled Chiller Condenser Maintenance Cleaning

Because of the large size of the plant, the customer had installed a fireman’s hose for the cleaning of the condensers. 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 onsite maintenance engineers carry out this task as part of their monthly schedule.

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Design Considerations for Air Cooled Chiller Condenser Maintenance

The kind of condenser in this article is:

Multiple Row Tubing

3 Rows

It has tubing of ½” diameter which is 3 rows deep. Each pass starts at the discharge header which is at the inlet to the condenser, goes down to the far end, through a condenser end turn, back to the discharge end, through another condenser end turn and back again to the liquid pipe end. The heat removed from the condenser, per kg of refrigerant, is the heat content of the vapour as it leaves the compressor, minus the heat remaining in the liquid at the end of the condenser.

6 Rows

Some condenser designs are up to 6 rows deep. This allows a small footprint of space where there is not much room for the location of the chiller. The downside to this, is that the chiller engineer can often struggle to locate the exact location of a leak when it is deep into the coil. If a condenser is too small, it will cause a higher head pressure and reduce the life of the compressor. We can arrange the lift out and repair of deep row condensers in our workshop.

Finned

This condenser has aluminium fins which are pressed around the copper tubing. This increases the surface area of the condenser heat exchange medium and so increases the dissipation of heat. The same amount of heat delivered to a condenser from the compressor must also be rapidly removed. For this condition to be reached, enough head pressure will need to be built up so that the condenser temperature is at least 15°C above the ambient. This is why the same chiller can be picked up and shipped to the Middle East and still work. It will just run at a higher discharge pressure/ temperature. There will, however, be a loss in the coefficient of performance as the higher pressures will result in more electricity in, versus the same amount of refrigeration effect out.

Forced Convection Type

The fans mounted on the ducting provide this forced convection. The air is sucked through the bottom of the condenser, across the 3 rows of tubes, along the fins and up through the fans. The air flow is stable as it enters the fins so good heat transfer is achieved. As it leaves the fins at the top, there is lower heat transfer as the air is turbulent.

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Fan Replacement during Air Cooled Chiller Condenser Maintenance

Spare fans are available onsite for replacement when individual fans fail. As mentioned above, these condensers are controlled with FSC's which reduce the occurrence of leaks. As well as this, fan speed controllers increase the lifespan of the fans. Because all of the fans run together, they speed up and slow down steadily. When high pressure control switches are used, they are set at different pressures. This means that some of the fans never come on until the head pressure is too high. This is usually due to a blocked condenser, failed fans or a high ambient. Because the fans have not come on for a long time, they are often seized or have suffered water ingress from the rain. An onsite maintenance engineer is available to help with the lift out and lift in of the replacement fans.

Pressure Relief Valves

Each of these condensers is fitted with a pressure relief valve (PRV) It is fitted into the discharge pipe on the inlet to the condenser. This is so that if the fans and the HP switch were to fail, the dangerous levels of pressure in the system would be vented. It is unlikely, however, that the HP switch would fail as this is a very reliable part. A PRV being fitted is often the requirement of insurance companies. The testing or replacement being arranged at scheduled intervals.

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

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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%. 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 chiller control systems click the Tag at the top of the page.

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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 Recovery during Process Chiller Service

Our high capacity refrigerant recovery 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.

Stainless Steel

Our unit is made from stainless steel because this metal works well with ammonia.

Condenser for Process Chiller Service

The condenser is made from tubing which is connected to ‘u’ bends on either end. These ‘u’ bends send the condensing refrigerant back along the next tube in the opposite direction. This process, back and forth allows time for the refrigerant to condense into a liquid. Fins are pressed around the tubing to increase the surface area and help to dissipate more heat from the refrigerant. A condenser fan is fitted to suck the air through the fins and so reject the heat.

Reciprocating Compressor

A four cylinder reciprocating compressor is fitted to the unit to provide the pressure difference to pump the refrigerant into the above mentioned condenser. It has an air cooled electric motor fitted which is open drive. This is because ammonia would corrode the windings of the motor if a semi hermetic compressor were to be used. Semi hermetic meaning that the windings, stator and rotor of the motor would be internal to the system. The motor is fitted in the vertical position with the four cylinders opposing each other on the central crank shaft.

Controls for Process Chiller Service

For safety reasons controls are fitted to the unit. These include:

HP Switch

If the recovery cylinder were to become over filled, the pressure would build up to a dangerous level. The TARE and the ullage need to be calculated prior to the job to prevent this from happening. The below mentioned liquid pipes have been designed with pressure issues in mind, but somewhere on the system would be the weakest point. This would burst causing a catastrophic refrigerant leak. The whole charge of the machine and all the refrigerant in the recovery cylinder would leak to atmosphere. The HP switch is set by the engineer on site to the correct level given the ambient conditions. This takes into account the temperature of the refrigerant and the safe operating pressure of the vessel.

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Refrigerant Liquid Pipe

Steel Braided

The refrigerant in its liquid phase is pumped into the above mentioned unit down a steel braided liquid pipe. The steel braiding is to provide additional protection from the pipe being damaged on the outside. Damage like being driven over by a forklift truck, or having sharp objects coming into contact with it. Also, the braiding helps to prevent bursts when pressure builds up on the inside. This can be due to a restriction, malfunction of system components or vessel overfilling.

PTFE

The inner part of the pipe is PTFE. Other types of plastics and compounds corrode due to the toxicity of ammonia. Polytetrafluoroethylene is the chemical name for this compound, it is a fluorocarbon solid and is considered to be non reactive.

Fittings

There are various metric and imperial thread types that can be used. This depends on the fitting size on the machine and the fitting size and type going onto the recovery unit. We carry a wide range of fitting types to step down and step up in size. We can go between male to female types and use male to male and female to female where necessary. We carry adaptors to go from metric to imperial thread types.

Remote Access during Process Chiller Service

We carry an extensive stock of liquid pipes that can be connected end to end to provide remote access. We will always try to get the recovery equipment as near as possible to the plant, but when this cannot be achieved, we can arrange access up cat ladders or the side of a building. We can use our lift and shift team to arrange the hauling of all the required equipment and ancillaries to any location. Just part of what we call the MAXIMUS ADVANTAGEAny Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere. Contact our office for prices for the above mentioned pipes.

Process Chiller 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 plant. 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 machines 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 recips. 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°C. The plant is around the middle of the lifespan and has been properly maintained.

Unlock Controller during R134a Chilling Plant Maintenance

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 chiller control systems click the Tag at the top of the page.

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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 during Water Chiller Maintenance

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 chillers running than necessary dramatically increases energy consumption.

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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 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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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 which has a higher head pressure than other commonly used HFC refrigerants. 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. Further leak tests were then carried out at normal operating pressures.

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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 led 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 did not 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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Read More industry news on the Refcom website.

 


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 valve has burned out the motor 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.

Restart after Chilled Water System EEV Service

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


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.

0161 370 7193

service@maximuschillers.com

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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 often made 'in house' so they can be 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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R407c Chiller Condenser Retrofitting

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


Chiller service of fan decks showing 8 fans

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.

0161 370 7193

service@maximuschillers.com

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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 during Chiller Fan Deck Service

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 for Seamless Operation

Now the fan speed controllers are fitted- there are no more leaks. 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? Need your fans replacing or the controls adjusting? 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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