Chiller Controls Company

Blue ammonia chiller with panel open during chiller controls company visit

Chiller Controls Company

Having an effective chiller controls company saves money! We at Maximus Chillers can repair any fault and upgrade where necessary. Read below to learn more…

Non Condensables

One of the non condensables that is found in a chiller is air. It had got into the system of the chiller in the photo due to a poor repair having been carried out. The end user had tried to save money by using a cheaper company to carry out a change of the suction strainer. They had forgotten to purge the pipework of air, leak test, and then pull a vacuum.

High Subcooling

The ingress of air had caused a ‘high subcooling’ message to appear on the PLC display. The controls work out the subcooling by looking at the pressure transducer reading, in this example it was 14 bar. Then, the onboard comparator understands the pressure/ temperature relationship of the refrigerant which is ammonia. This gave the saturation point temperature of 39°C. Also, the temperature sensor reading on the condenser was 25°C. The 14°C difference between the two temperatures was the subcooling. The parameters in the controls trigger this message if the subcooling is more than 12°C.

Air Purging

Our engineer attended site to carry out air purging according to standard industry guidelines. Our Risk Assessment Method Statement outlined the necessary PPE that was needed when handling this refrigerant. It also outlined the training and certification required by our engineer to handle anhydrous ammonia.

Subcooling Readings

He then ran the system up and checked the subcooling readings again. The condenser pressure was now 11 bar which corresponds to a saturation temperature of 31°C. The condenser temperature was still 25°C, so the subcooling was now 6°C. This was now below the alarm trip out level.

Dalton’s Law of Partial Pressures

This gas law states that all gasses in a pressurised vessel will act as if they are on their own. Therefore, with the air that was in the system, the condenser pressure was 14 bar, then after the air purging it was 11 bar. This means that there was 3 bar of air sat on top of the liquid refrigerant in the condenser. The air was causing a false reading of subcooling and therefore triggering the fault condition.

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Electrical Problems

Another fault message which had occurred during the time we have maintained this machine was oil separator low temperature. The oil separator is the vessel, just visible, to the left of the panel in the photo. This alarm is critical to protect the screw compressor from running with cold oil which will cause an expensive failure.

No Heater Burn Out

The oil separator heater was found to be off despite the cold temperature of the oil. The obvious reason was that it had burned out. The breaker was found to be in the 'on' position and there was no electrical charring visible.

Ohms Checked by Chiller Controls Company

When our engineer checked the ohms readings, they were found to be okay and there was no short to earth.

Run Signal

It was found that the 3 phase contactor was not pulling in to bring the heater on. Therefore, the next thing our engineer checked was weather the controller was sending out the run signal. It was- with 24v coming from the controller and the light being lit on the display. Somewhere in between, there was a problem…

Blown Relay

After consulting the wiring diagram, our engineer traced the fault to a blown relay. This relay provides a step in between from the 24v coming from the controller, to the 240v coil on the oil heater contactor. Rainwater had ingressed through a screw hole in the back of the panel. It had dribbled to the location of the A1 coil terminal on the relay. Here, it had been ‘tracking’ a few volts to earth. This was sufficient to burn out the coil without blowing the fuse. A drying agent suitable for electrical components was used, then the hole was sealed using a compound. There was a spare relay of the same type in the panel, so it was a quick job to swap it out.

Monitoring by Chiller Controls Company

Having done this, the contactor pulled in and the oil heater came on. Balanced amp readings were recorded on all three phases of the heater and the oil started to warm up. The oil separator temperature sensor was monitored for an hour on the controller. When the oil temperature rose to above the trip out level of 46°C, the fault condition automatically reset and the chiller came back on.

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Software Upgrade by Chiller Controls Company 

We had also previously found that the controller software was too finicky- causing a lot of spurious trip outs. Therefore, we decided to design our own software and upload it. This is easy to do because the controller is Bejer Electronics. It is a blank control system which can be used for almost any chiller, or other application. Read below to find out how we did it…

Chiller Controls Company Reliability

We rationalised what the customer needed and developed an upgraded program which was much more reliable. Getting a chiller to settle down and cost the customer less money is what we at Maximus Chillers are all about.

Chiller Controls Company's Test Rig

The controller had been removed from the chiller and wiped of its program. Then, the finished program was uploaded to the controller and a test rig set up. This was to iron out any teething problems before sending it back out into the field.

Laptop Plug In

When our engineer attended site, he fitted the upgraded controller and plugged it into his laptop. All of the program settings can be adjusted on the controller without the need of a laptop by entering the correct passwords for the program level required. However, a laptop has a bigger screen and so multiple readings can simultaneously be monitored. This facilitated the commissioning process.

Chiller Controls Company Testing and Adjustment

The chiller was run tested under various load conditions to check its performance. Also, all the fault conditions were either simulated or tripped out on the chiller. This was so that the program could be put to the test and adjusted accordingly. There were minor problems with fault timers which were adjusted, one at a time, so that no spurious trips would occur.

Completion

After monitoring the chiller for the rest of the day, it was time to talk to the customer about the job and get a signature. This chiller is in South West Wales, so it is a long, but very scenic, drive back for whichever of our engineers attends site. Read more about chiller upgrade.

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Two blue open drive Vilter reciprocating chiller compressors being maintained in a plant room

Reciprocating Chiller Compressor Maintenance

Reciprocating chiller compressor maintenance for two low temperature ammonia chillers. Reciprocating means a forwards and backwards motion in a straight line. This is achieved by converting the circular motion of the crankshaft, into a linear motion using the connecting rods. The pistons are on the end of the con rods, which slide up and down inside the cylinder liners.

Piston Rings

There are two types of piston rings which are used:

Compression Ring

This is the upper ring and is designed to a high tolerance to prevent the refrigerant vapour from bypassing the piston.

Oil Ring

This is the lower ring and is designed to regulate the oil flow around the piston.

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Cylinder Head

The cylinder head is usually cast iron and serves as a pressure plate. It holds the valve gear and has passageways for the suction and discharge of the refrigerant. The discharge pressure varies according to the kind of refrigerant and application. For a 0°C saturation it can be as low as 7 bar on R134a, or as high as 30 bar on R410a. The discharge temperature is usually around 60°C to 80°C which is recorded on our detailed Tick Sheet during the maintenance.

Valve Gear

Helix springs or reeds are popular with this type of compressor. Wave springs are another design that can be seen in operation on our YouTube channel. The video uses a cut away view and the oil is depicted in yellow. These springs control the suction (intake) and the discharge (exhaust) of the refrigerant…

Suction

The suction valves have the least amount of failures because the refrigerant is cool, low pressure and is carrying oil.

Discharge

The discharge valves, however, can have heavy molecules of hydrocarbons collect on them in the form of carbon. This causes them to not seat correctly, resulting in a deterioration of compressor performance. The difference in pressure between suction and discharge, otherwise known as the compression ratio, is a check that we carry out during the maintenance. The pressure and temperature is higher on the discharge valves, so more stress is exerted on to them. Therefore, they have a reduced lifespan by comparison to suction valves.

Top Dead Centre

The piston needs to come as close as possible to the cylinder head to create the largest amount of compressed refrigerant. This is called the clearance space which is usually less than 0.5 mm.

Discharge Header Safety Spring

This spring is fitted into the cylinder head and allows the valve gear to lift when:
• Liquid refrigerant slugs back to the compressor due to poor heat exchange in the evaporator.
• An oil slugging condition occurs.
• Water is drawn around the system from a burst condenser or evaporator.
As a compressor cannot compress a liquid, the valve gear lifting prevents an expensive compressor smash up from occurring.

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Reciprocating Chiller Compressor Maintenance of Shaft Seal

The compressors in the photo are open drive. Each has a shaft seal which has two, mirror finish rubbing surfaces. One seal turns with the crankshaft and the other is stationary. We check the amount of oil that is seeping from the shaft seal on every visit. When we notice that the level in the oil bottle is too high, we arrange a visit to change the shaft seal. This can be done without disruption to your process, as the other compressors can be left running while we carry out the work.

Reciprocating Chiller Compressor Maintenance of Drives

This kind of compressor is usually driven by an in line electric motor, as in the photo. It can also be driven by ‘v’ belts from an electric motor which is located to the side of the compressor. The ‘v’ belts are checked during the visit to see if there are any cracks on the inside working surface. We replace these with the pre ordered spares that are on site at no extra charge. They are then re tensioned according to standard industry guidelines.

Reciprocating Chiller Compressor Maintenance of Crankcase

This is a cast iron housing that all of the above components fit into. It provides the necessary support and strength for the compressor to operate at its high temperatures and pressures. The crankcase heater keeps the oil at operating temperature during the off cycles. It is usually a bore type which pushes into a hole in the casting. We check for the correct operation of the crankcase heaters and replace them where necessary. This is another spare that is kept on site, so that a return visit is not needed.

Service Ports

These bolt on to the compressor crankcase. They can be positioned in various directions, depending on which way the suction and discharge pipes go. The compressor can be valved off when it is being worked on. These ports are used by engineers to attach their gauges during the maintenance. On each visit, we check the calibration of the system pressure transducers by checking them against our gauges.

Reciprocating Chiller Compressor Maintenance of Oil Pump

This is a gear type pump which is fitted to the end of the compressor crankshaft. The pump sucks the oil through a filter from the sump of the compressor. Then, it is discharged from the pump, down the crankshaft passageways to the connecting rods. From here it travels up the con rod passageways and out through the pistons to the cylinder liners. Here, it provides the essential lubrication between the pistons and the liners. According to the maintenance schedule, we periodically change the oil filters to ensure the optimum running conditions of your compressors.

MAXIMUS ADVANTAGE™

If a compressor smash up occurs and the compressor is found to be obsolete- don’t worry. We can adapt the compressor mountings and the pipework for a different compressor. This is part of what we call The MAXIMUS ADVANTAGE™ Any Chiller- Any Problem- Any Part- Any Refrigerant- Anywhere.

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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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PLC and relay board in a panel during chiller service company visit

Chiller Service Company

Electrical Testing

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

News Article No.3

Doing this often aids with the diagnosis even when there is a wiring diagram, as having your eyes on a component often makes more sense than a symbol. In any case, our engineers carry out system testing with Fluke multimetes and ammeters.

F-gas Leak Testing by Chiller Service Company

We also carry a range of thermocouples and probes to be used in conjunction with our calibrated digital thermometers. We use these along with comparators to carry out leak testing. After fitting the probes, we first have a visual look around for a sign of a gas leak. All parts of the pipework and system components are inspected. Then, we carry out a full refrigerant diagnosis to determine that the refrigerant system is operating with a full charge. Reports for each chiller are completed and filed in the onsite F-gas leak register. A history can be built up to assess the serviceability of the plant and the frequency of any leaks.

Chiller Service Company Monitoring

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

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Chiller Service Company Evaporators

Shell and Tube

These have a rolled steel shell, welded down the seam with and end plate on either end. The water system pipes can be bolted to the sides or the end. The endplate can be removed for access to the waterside of the tubes. A strainer is fitted to the inlet to catch any foreign objects that may have been carried around the water system. Inlet and outlet gauges are fitted for the monitoring of the water system readings during a visit. 

Flooded

On larger chillers, the screw or centrifugal compressor is mounted directly on top of the flooded evaporator. The refrigerant is in its liquid phase on the outside of the tubes. These are arranged in a rack extending through the length of the shell. The warmer process water running through the tubes causes the refrigerant to boil off. A sight glass is usually available to check the state of the refrigerant evaporating on the copper tubes. The suction from the top of the evaporator goes round a baffle so as to prevent the slug back of liquid refrigerant into the compressor. The refrigerant flow into the evaporator is controlled by the expansion valve…

Expansion Valves

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

Multiple System N+1

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

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Chiller Service Company Condensers

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

Pressure Transducers

Johnson Controls

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

Keller

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

R134a Refrigerant

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

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Chiller Service Company Compressors

Centrifugal Compressors

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

Screw Compressors

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

Scroll Compressors

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

Compressor Failure

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

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

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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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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 overhead gantry crane and specialist equipment to hand- Maximus Chillers completes the picture. We have a lift and shift team who are skilled at getting the compressor out of the most awkward locations. A variety of lifting equipment is used, including 3 phase electric hoists and trollies. Our team do this kind of work all the time, so they are accustomed to overcoming all the difficulties and obstacles.

Screw

Screw compressors are remanufactured on the bench. With compressed air and bearing tools- our skilled technicians are seasoned in high tolerance measurements. The bearing clearance and shaft run out are accurately measured and adjusted. This means that the useful life of the compressor is extended, often to beyond the lifespan of the chiller.

Scroll

We have a range of off the shelf Copeland compressors for a fast lead time on process chiller repairs. These can be sent to site on the day using our fast door to door supply chain. We have all the sizes of compressor available. The pipework and mountings can be adapted too. This means that if your compressor is a different make with a longer lead time- our compressor will be fitted and adapted to your machine- fast!

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. This is done free of charge and ensures that the new condenser will fit easily into the old chiller. The exact subcooling requirement of the old condenser is taken into account which is duplicated on to the new condenser. This means a like for like swap can take place even when the old condenser is obsolete.

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. We have these condensers built to order by our bespoke manufacturer. They are shipped to site on an overnight delivery, so we can get straight down to work in the morning. We therefore minimise downtime in the swap out of this part.

Chiller Parts Supplier of Evaporators

Shell and tube are 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 and into the refrigerant. This is latent heat as the liquid refrigerant boils off into a vapour. Where the heat exchange does not greatly improve after cleaning, we recommend replacing this part.

0161 370 7193

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Vibration Eliminators

We have all of the sizes of anacondas on the shelf in our stores. This saves on the delivery time to site when your process is off due to the chiller. Maximus Chillers will get you up and running- fast! We can also fit flexible vibration hoses which achieve the same result as anacondas. Whereas two anacondas are fitted vertically and horizontally, only one, long vibration hose is needed.

Chiller Parts Supplier of Flushing Agent

When things go wrong, we stock a solvent based flushing agent which is blown through the system using nitrogen. The waste product is caught on the far end in drums that come with the kit. This is then returned to the suppliers for recycling.

Refrigerant Economizers

These are another term for a subcooler. If the refrigerant is further subcooled after the condenser- the system will run more efficiently. This part usually takes the form of a plate heat exchanger with an expansion valve providing the refrigeration effect needed to further subcool the remaining liquid.

Chiller Parts Supplier of 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 on site. Then we can get your chiller up and running with the correct readings in the controls. This will assist your onsite maintenance engineers in giving us useful readings when we are in communications over the phone.

Chiller Parts Supplier of Ammonia and HFC Refrigerant

A full selection of refrigerants are available including: anhydrous ammonia, R407c, R134a and R410a. These refrigerants come in small 12kg, midi 26kg, large 56kg and bomb 800kg sizes. Our vehicles are equipped with tail lifts and lifting gear to facilitate delivery. We can therefore arrange the delivery and collection of refrigerant at your site, free of charge, anywhere in the UK. For our overseas customers, we arrange the transportation from the local suppliers.

Chiller Parts Supplier of Oil

Low, medium and high viscosity oils in 5ltr cans and 20ltr drums are ready for shipping from our storage area. It is critical to select the correct grade of compressor oil as bearing wear and reduced service life will result. We take regular samples of this oil to see if things are starting to go wrong in the compressor. We can then nip these problems in the bud, giving you dramatic savings.

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.

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


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

Chilling Plant Service

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

Transducer Required Chilling Plant Service

The 4-20mA transducer needed replacing as it was reading low by a long shot. Therefore, the PLC was not bringing the fans on as it should. The pressure in the high side of the system was getting up to 40 bar. This is because the refrigerant was R410a 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.

0161 370 7193

service@maximuschillers.com

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


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