Chiller Maintenance Checklist

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.

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.

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Brazing equipment box and vibration eliminators during packaged chiller service

Packaged Chiller Service

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

Leak Testing During Packaged Chiller Service

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

Vibration Eliminators

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

Brazing During Packaged Chiller Service

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

0161 370 7193

service@maximuschillers.com

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Pressure Test During Packaged Chiller Service

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

Vacuum Pump

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

Refrigerant Saturation

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

Subcooling

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

Superheat

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

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Read more about reducing refrigerant leaks at the Institute of Refrigeration | Click Here


Engineer carrying out process chiller service with yellow and black cylinder

Process Chiller Service

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

Refrigerant Decant for Process Chiller Service

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

Process Chiller Refrigerant Leak Service

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

Pressure Leak Test

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

Dehydration Process

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

0161 370 7193

service@maximuschillers.com

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Charging of Refrigerant

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

Run Testing

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

Remote Service Monitoring of Process Chiller

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

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Follow this link to purchase BESA pressure testing technical bulletin Click Here


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

Chilled Water System Condenser Repair

Chilled Water System Condenser Beyond Repair

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

Condenser Removal

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

Condenser Replacement

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

0161 370 7193

service@maximuschillers.com

Contact Form

Pipework Repair

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

The Evacuation Process

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

Recharge and Test Operation

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

Related Articles:
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Read about air cooled condenser installation at the Institute of Refrigeration | Click Here


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