Chiller Maintenance Checklist

A pile of completed chiller maintenance checklists on a table

Chiller Maintenance Checklist

News Article No.1

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

0161 370 7193

service@maximuschillers.com

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Water System Temperature

The chiller should be:

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

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

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

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

Small Chiller Maintenance Checklist

Low Refrigerant Pressure

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

Breakers

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

Condenser

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

High Pressure Switch

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

Large Chiller Maintenance Checklist

Suction

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

Discharge

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

0161 370 7193

service@maximuschillers.com

Contact Form

Chiller Remote Monitoring

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

Parts

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

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

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

Related Articles:
Air Cooled Chiller Planned Maintenance

Water Chiller Maintenance

Process Chiller Maintenance Visit

Chilled Water System Maintenance

Air Cooled Chiller Maintenance

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Read more about chillers on Wikipedia | Click Here


Vacuum pump and green compressor during air cooled chiller superheat maintenance

Air Cooled Chiller Superheat Maintenance

Air cooled chiller superheat maintenance at Maximus Chillers. During the visit, we found a high superheat condition with an Italian chiller. The customer had reported a low refrigerant charge trip out. The customer raised the order, so we got straight to work on the leak during the maintenance visit.

Pressure Temperature Relationship

Put simply, the higher the pressure, the higher the temperature of the refrigerant- this is consistent with Charles’s Law of Constant Volume. The refrigerant was found to be at a higher temperature above saturation (or boiling point) than usual- which is a high superheat condition. The chiller runs on R134a, which is a HFC refrigerant.

Air Cooled Chiller Superheat Maintenance with Leak Finding

Our engineer used his leak identification equipment to find the leak. After looking around the chiller he found the leak adjacent to the shell and tube evaporator, where 4 bolts hold the suction pipe on. This coupling is sealed with a gasket.

0161 370 7193

service@maximuschillers.com

Contact Form

Chiller Pump Down

Because of the location of the leak, our engineer decided to pump the chiller down to the condenser and valve the evaporator off. A lot less time consuming than setting up the recovery unit to decant the refrigerant.

Air Cooled Chiller Superheat Maintenance with Leak Repairs

He used his Allen key set to remove the suction pipe from the evaporator. On inspection, the paper gasket had deteriorated then been pushed out by the pressure in the system. All of our engineers carry an extensive range of commonly used parts and materials as standard in their cars. This is to reduce down time for the customer. He made up a new paper gasket, coated it with a special sealing compound, then re fitted the suction pipe to the evaporator. He then used his torque wrench on the Allen key bolts to the correct manufacturer’s recommendations. The system was then pressure tested and dehydrated as per standard industry guidelines.

Screw Compressor

The superheat value at the Bitzer screw compressor was found to be within normal operating values after additional refrigerant was added to the system. A further follow up leak test was carried out at a later date according to F-gas regulations. The paperwork being kept in the F-gas file in the chief engineer’s office.

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

Related Articles:
Air Cooled Chiller Planned Maintenance

Water Chiller Maintenance

Process Chiller Maintenance Visit

Chilled Water System Maintenance

Air Cooled Chiller Maintenance

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Chiller Maintenance Checklist

To read more about vapour compression on Wikipedia | Click Here


Green Bitzer compressor being vacuumed during HFC chiller service

HFC Chiller Service

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

HFC Chiller Diagnosis Service

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

Return Visit to Decant the Refrigerant

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

0161 370 7193

service@maximuschillers.com

Contact Form

Looking Around the Pipework for a Leak

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

Brazing and Pressure Testing

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

The Evacuation Process for HFC Chiller Service

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

Recharge and Run Testing

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

Related Articles:
Chilling Plant Service

Global Chilled Water System Service

Chilled Water System EEV Service

Water System Service of Evaporator

Chiller Service of Fan Decks

Process Chiller Service

Process Chiller Vacuum Service

Read more about a film blowing machine on Wikipedia | Click Here


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