Data Centre Cooling

Data Centre Cooling- Service and Maintenance

Close Control Server Racks - Data Centre Cooling
Server Racks

Close Control Computers in a data centre work better the colder they are. Weather the compressor is in the computer room requiring over-ride of the fire alarm during hot works; or outside- we are seasoned in fast and effective repairs

Extend the life of your Cooling Systems

If you have been given an expensive quote for new- stop! We have the capability to keep your data centre cooling system running! Even if it means fitting a different controller it is not a big deal for our highly skilled engineers. We can even source different compressors and expansion valves, then fit them to the existing machine. Regular maintenance is the key to extending the life of your air conditioning systems. Small problems can be nipped in the bud before they become big problems to keep your data centre nice and cool at all times!

CRAC Server Aisle
Server Aisle

CRAC or computer room air conditioning can be grouped into various types: mezzanine down-flow systems, up-flow systems, out-flow systems, chilled water fed units or CRAH. Whatever type of cooling is in your data centre, we will get the unit going- whatever the problem

Undersized Air Conditioning Systems

This is a common fault with a data centre. The heat load is correct when the data centre is opened. Then, new aisles are built with loads of new racks and heat. The result is the air conditioning never goes off and the computer room is always running hot

Air Conditioning Repair

Then, when there is a break down, servers start shutting down and computer engineers start getting stressed!

More Air Conditioning

The solution is more AC Units. The ones that are there are okay, they just need some more back up. N+1 is the usual way to do it- that is to say a running system and a stand-by system ready to come on if the running system goes down

Switch Over Panel

A switch over panel can be used, this enables the stand-by system when the panel receives a fault signal from the failed unit. Another, more simple way to do it is to have the stand-by system set 2° above the running system. This can be replicated to all systems throughout the data centre

Thermostatic Expansion Valve

This fault can catch an inexperienced engineer out as the symptoms are nearly the same as a system running short of refrigerant: low back pressure and high superheat. The only difference is a clear sight glass with a solid column of refrigerant behind it. This is because the refrigerant is stuck behind the failed TEV

Power Element Failure

Usually the power element fails on top, this fights against the spring to open the valve when the superheat goes up. Some thermostatic expansion valves can be dis-assembled and the power element replaced separately, others come as one complete unit. Usually they are brass so silver solder is used to make the joint

Pre-set Expansion Valve

Once fitted the usual pressure test, vac and re-charge is carried out. One thing that is not known to every engineer is that the expansion valve comes pre set to 5° superheat so does not need to be adjusted through the whole of it's life. The only reason manufactures put the adjustment screw on is to balance the valve to a slightly different sized compressor

Compressor Sizes

Compressor and TEV manufacturers make their components certain sizes so they match. The ltrs/sec through the valve is balanced against the ltrs/sec through the compressor

Sight Glass

The sight glass is just an indication, not a be all and end all, so the system is confirmed by taking superheat and subcooling readings

Close Control Commissioning

The most popular design is the down flow unit. This is because it blows through the data centre mezzanine floor, up through grills and up through the computer racks. The return air is sucked back in from the top, which is where it rises to anyway, as warm air is thinner

Decommission

The first thing is to de-commission the old unit. The gas is decanted and the power supply isolated and removed. Usually it is easier to break the data centre cooling unit apart inside and take the parts out separately- most of it is then recycled

New Unit In

Getting the new unit in is a little more hard work. Quite often the unit will only just go under doors so we roll them on broom sticks to get them through- just like the Egyptians! Once it is in place it is then bolted down and the power supply connected. The condenser is bolted down outside and pipework connected between the two units. The pipework is then strength tested and pressure tested. A vacuum pump is fitted to both sides of the system and 1 Torr is pulled to remove any moisture and non condensables

Commissioning

The fan speed controllers and safety switches are set. The way of determining the charge is to put in around half the charge and keep putting it in to the liquid side of the evaporator until the superheat comes down to between 6° to 12°. A detailed tick sheet is completed. Now the data centre cooling machine goes into seamless operation

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