# What cooling does a small server or comms room actually need?

*The CFM team · F-Gas certified air conditioning engineers · CFM Cooling · Commercial*

A dedicated, 24/7-rated cooling unit sized to the heat load of the equipment — not a leftover office split running flat-out. IT kit fails hot, and it fails expensive: a comms room that loses cooling on a summer weekend can cook hardware before anyone's back in the building. Good small-room IT cooling means a properly sized unit rated for continuous duty, condensate handled safely away from the racks, high-temperature alerting, and a service schedule that keeps the whole arrangement boring.

## Why office splits fail here

Comfort units are designed for people-hours, not 24/7 duty, and their controls assume someone will notice a problem. Run one continuously against a rack of servers and you shorten its life dramatically — then it fails on a bank holiday, silently.

## Sizing is about the racks, not the room

The heat load comes from what the equipment draws, not the floor area. We calculate from the actual kit — servers, switches, UPS losses — with headroom for growth, and spec redundancy where downtime genuinely costs money.

## The cheap insurance

A high-temperature alert (a text before the smoke) and a twice-yearly service cost a fraction of one dead server. If your comms room's cooling has neither, that's the first conversation to have.

> IT kit fails hot and it fails expensive — usually on a bank holiday. A duty-rated unit and a high-temperature alert cost a fraction of one dead server.
>
> — The CFM team, F-Gas certified air conditioning engineers

## Related questions

### Our comms cupboard is tiny — does it still need cooling?

If it holds powered kit in an enclosed space, heat accumulates. Sometimes ventilation is enough; sometimes it needs a small dedicated unit. A survey with a heat-load calculation answers it definitively.

### What about redundancy?

Where downtime costs real money, two smaller units with a duty rotation beat one big one — either can carry the room while the other's serviced or failed. We'll tell you honestly whether your room justifies it.

### Can you add alerts to existing cooling?

Usually yes — independent high-temperature alerting can be retrofitted regardless of the unit's age, and it's the single highest-value upgrade for an unmonitored room.

### Our server room keeps overheating in summer even with the AC on — why?

Almost always one of three: the unit is a comfort split that isn't rated for 24/7 duty and is giving up under continuous load; it was sized to the room rather than the heat the racks actually throw out; or it's overdue a service and its output has quietly dropped. A heat-load calculation against your real kit tells us which — and whether the fix is a correctly-rated unit, a second one for redundancy, or a service plus a high-temperature alert.

---
Canonical page: https://www.cfmcooling.co.uk/guides/server-room-cooling-basics