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

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Chiller Remote Monitoring

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

Parts

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

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

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

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


Two green screw compressors being maintained in an air cooled chiller

Air Cooled Screw Chiller Maintenance

We recently carried out air cooled screw chiller maintenance at a site we look after in the North West. The plant is described such because it uses two Bitzer screw compressors to create a pressure difference in the R134a refrigerant. The plant has been designed to be remotely operated…

Chiller Remote

This is a way of operating the chiller remotely. Instead of the end user having to walk up to the machine each day to check for faults (chiller local) the plant can be remotely operated and monitored.

Run Signal

The run signal to start the chiller is sent by a relay being energised in the BMS panel (Building Management System) in the plant room. When the chiller receives the run signal, it shows the chiller on message.

Fault Feedback

When the chiller develops a fault, the chiller energises a relay, sending a fault feedback signal to the BMS panel. This fault signal causes the run signal to drop out and a new run signal to be sent to the adjacent redundant system.

BMS Panel

The BMS panel runs contactors which bring the water system pumps on, it also receives analogue signals from temperature sensors on the water system. These inputs and outputs are wired into a PCB which converts them into a data signal. This signal is sent down a CAT 5 plug cable to the supervisor in the facilities management room in the building below.

Remote Monitoring During Air Cooled Screw Chiller Maintenance

A supervisor is a computer which has graphic monitoring of the chillers and the air handlers. The supervisor, is connected down a phone line to the BMS company. Often, the chiller is remotely operated and monitored from a laptop used by a BMS engineer working from home.

0161 370 7193

service@maximuschillers.com

Contact Form

Air Cooled Screw Chiller Maintenance Parts

With a comprehensive range of chiller parts available, off the shelf, for air cooled chillers- look no further than Maximus Chillers for all your chiller parts. We can also supply parts mostly same day. A specialist part on this chiller is the electronic expansion valve driver- this regulates the steps in the expansion valve to ensure correct superheat in the shell and tube evaporator. An electronic expansion valve driver is also available to regulate the expansion valve in the refrigerant economiser. This acts to subcool the refrigerant to ensure optimum system efficiency.

Diagnosis During Air Cooled Screw Chiller Maintenance

Should you need chiller diagnosis- one of our trained professionals onsite during the maintenance will identify the issue with his system test equipment.

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

Read more about remote monitoring and control 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

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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


7 large air cooled chiller condensers maintained with 12 fans each

Air Cooled Chiller Condenser Maintenance

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

Fan Speed Controllers

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

0161 370 7193

service@maximuschillers.com

Contact Form

Air Cooled Chiller Condenser Wash Down Maintenance

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

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

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

Chiller Maintenance Checklist

Read more about HVAC air coils on Wikipedia | Click Here


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

Air Cooled Chiller Planned Maintenance

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

Critical Air Cooled Chiller Planned Maintenance

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

Air Cooled Chiller Oil Planned Maintenance

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

0161 370 7193

service@maximuschillers.com

Contact Form

Economiser

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

Head Pressure Control

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

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

Related Articles:
R134a Chilling Plant 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 Superheat Maintenance

Air Cooled Screw Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Chiller Maintenance Checklist

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


Air cooled chiller maintenance of two white chillers with green compressors

Air Cooled Chiller Maintenance

Air Cooled Chiller Maintenance Bodger Watch

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

Air Cooled Chiller Antifreeze Maintenance

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

0161 370 7193

service@maximuschillers.com

Contact Form

On Site Maintenance Engineer

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

Antifreeze Removal

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

Clear Site

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

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

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

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

Related Articles:
R134a Chilling Plant Maintenance

Water Chiller Maintenance

Air Cooled Chiller Planned Maintenance

Process Chiller Maintenance Visit

Centrifugal Chiller Maintenance

Industrial Chiller Maintenance

Air Cooled Chiller Superheat Maintenance

Air Cooled Screw Chiller Maintenance

Air Cooled Chiller Condenser Maintenance

Chiller Maintenance Checklist

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