Data Centre Chillers

Servers and aisle in data centre being cooled by chillers
Mezzanine floor with chilled air blown up through the grills

The Service, Maintenance and Repair of Data Centre Chillers

We at Maximus Chillers will keep your servers nice and cool by optimising data centre chillers.

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Capacity of Data Centre Chillers

Data centre chillers are usually air cooled with multiple systems, each having around 500 kW in capacity. They are arranged in rows, so a site with 4 of these chillers will have around 2 MW of cooling capacity. Smaller data centres have smaller chillers which have a lower capacity.

N+1 Redundancy

Regardless of the size of the plant, N+1 redundancy is built in. This is because these chillers are critical plant suppling chilled water to a critical application. If the chillers were to fail, the data centre servers would shut down on their internal over temperature switches.

Service of Data Centre Chillers

All chillers need to be repaired due to breakdowns, or need service at pre arranged intervals according to the maintenance schedule. The above mentioned redundancy takes this into account. Even if half of the systems are down, the required chilled water temperature will still be supplied to the data centre.


The chilled water goes through a pump set and is supplied to a Computer Room Air Handler. This is a down flow unit with an internal blower which discharges through a heat exchanger and into the mezzanine floor. The chilled air is then forced up through the grills in the floor and through the server racks.


The refrigerant saturation in the chiller is usually just above 0°C. This prevents the inconvenience of ice forming on the inlet to the evaporator. In the evaporator, the refrigerant absorbs latent heat from the return water and chills it down to around 6°C. This chilled water goes through a 3 way valve in the down flow unit which is controlled by a PLC. The programmable logic controller controls the various Inputs and Outputs around the unit and regulates the position of the 3 way valve. Data centre engineers want the computer room temperature to be as cold as possible, usually 18°C because computers work better at lower temperatures.

What We Offer for Data Centre Chillers

All of our cars are a mobile workshop carrying an extensive selection of commonly used parts.

The industry's best engineers, time served, qualified and adept at getting you up and running- fast!

State of the art equipment which is regularly calibrated, tested and replaced. This makes our diagnosis right first time.

Why Choose Us for Data Centre Chillers?

Customer satisfaction is the key to ensuring the longevity of a relationship. If you are not happy, you will try another company next time the maintenance contract runs out. Therefore, as well as having a technical capability that is second to none, we will sort out any issues to ensure that you get the best service available.

0161 237 3727

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Case Study of Data Centre Chillers

We look after a data centre in the North West which uses 3 MW of chillers. We were called out because the data centre computer room temperature had risen from the usual 19°C to 26°C. The computer engineers were worried that the servers would start shutting down. When our engineer arrived, he noticed that all of the 6 chillers were off on a flow fail fault. The security guard informed him that there had been a power failure prior to the call out. There is an uninterruptible power supply system on site, but something had gone wrong with the switch over. The mains power was now back on, but the water system pumps were still off.

Power Spike to Data Centre Chillers

The power failure had caused a spike in electricity which had blown a control fuse in the panel which supplied the pumps. Our engineer was quick to diagnose this because he routinely checked all of the fuses with his multi meter as a matter of course. We carry an extensive collection of commonly used parts in each vehicle. Therefore, we had a replacement fuse to hand of the correct amperage.

Pump Start Up

Having replaced the fuse, our engineer reset the pump set controls and restarted the pumps. Correct rotation and air locks were checked for, then a good pump outlet pressure was recorded. This chilled water pump is of sufficient capacity to supply chilled water to all of the 6 chillers.

Auto Restart of Data Centre Chillers

The chillers have been programmed to restart automatically in the event of a power failure. The flow fail fault is auto reset too- so as soon as the flow switches detected the water flow, the chillers went through a timer and started back up.

Running Data Centre Chillers

As the chilled water temperature had now got up to the same temperature as the data centre, the chillers all started to load up to 100%. This was a really nice sound to all on site as there had been a lot of tension until the restart.

Down Flow Units

Now that the chillers and pump sets were reinstated, the down flow units were tested. These units were on a different power supply to the one which fed the chillers. Therefore, they were all functioning satisfactorily with the 3 way valves supplying chilled water to the heat exchangers.

Data Centre Chillers Achieving Setpoint

Within an hour the data centre temperature had got down to the required setpoint. The chillers had unloaded and some of the systems had gone off. This was because we had arranged the chillers in a configuration of lead chillers and lag chillers. Each time we complete the maintenance, we change this configuration to balance the run hours of the plant.

Next Steps...

If you are busy, why not fill out our Contact Form it works and is monitored too- try it!

If you have pictures of data plates and chillers to send, you can attach them in an email to

Or, sometimes it's easier to discuss your requirements by giving us a bell. Our Technical Support Engineer is on the end of the phone on 0161 237 3727

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