Air conditioning for server and comms rooms

Why a server room needs its own cooling

Almost all the electricity your servers, switches and UPS use ends up as heat in the room. That heat doesn't stop at 6pm or at the weekend, and it doesn't drop much in winter. The office air conditioning, which switches off when everyone goes home, can't look after it.

So a server room needs a system that runs all the time, on its own controls and its own electrical supply. It also needs an outdoor unit that can keep cooling in winter, because a server room needs cooling even on a frosty night. Not every model is rated for that, so we check the manufacturer's cooling operating range before we specify one.

How cool is cool enough?

Equipment cares about the temperature of the air going into it, not the temperature by the door. ASHRAE, the industry body whose thermal guidelines the IT world uses, recommends an inlet air range of 18 to 27°C for most server equipment. Your hardware maker's own limits always come first.

Many rooms are run far colder than they need to be, which wastes energy. A steady temperature within the recommended range, with good airflow to the front of the racks, matters more than a very low set point.

Comfort units or close control?

Two different kinds of equipment. The honest answer depends on the size and importance of the room.

We fit split systems for small server and comms rooms. If your room needs full close control, we'll say so at the survey and suggest you use a specialist.

Standby units and N+1

If one air conditioner is all that stands between your servers and a shutdown, a single fault becomes an outage. N+1 means fitting one more unit than you need: if the room needs one unit, you fit two, and either can carry the load alone.

Manufacturers including Daikin and LG make controllers for exactly this. Duty rotation swaps the running unit and the standby unit at set intervals, so both wear evenly and you know the standby works. If the running unit fails, the controller brings the standby in automatically.

For the best protection, give each unit its own electrical supply and, where possible, its own outdoor unit, so one fault can't take out both.

Alarms and good practice

Cooling is only half of it. You need to know quickly when something goes wrong.

• A high-temperature alarm that's independent of the air conditioning, so it still works if the units fail
• Alerts sent to someone who can act, by email, text or your monitoring system, not just a local beep
• Use the fault output on the air conditioning controller where your monitoring can read it
• Indoor units never directly above racks, and condensate piped away from equipment
• Blanking panels in empty rack spaces so hot exhaust air doesn't loop back to the front
• No portable air conditioners as the long-term answer: they need a vent and a water bucket emptying
• Plan for growth: new kit adds heat, so leave headroom in the sizing

How we size and fit server room cooling

1. 1

   Measure the load

   We look at the IT equipment's power draw, the UPS, lighting and any heat coming in through walls and windows.

2. 2

   Agree the risk

   We talk through how critical the room is, and whether you need N+1, duty rotation and remote alarms.

3. 3

   Written quote

   You get a fixed price plus VAT, with each option shown clearly so you can choose the level of resilience.

4. 4

   Install without downtime

   We plan the work with your IT team so the equipment keeps running. Temporary cooling can be discussed if the room is already hot.

5. 5

   Commission and test

   We commission the system, test the changeover between units and confirm the alarms reach the right people.

Server room cooling prices

Server rooms are quoted after a survey, because resilience options change the price. As a guide, a commercial wall unit starts from:

• Commercial wall unit

  Fitted in business hours

  from£1,795+ VAT

Server room air conditioning questions