Server room cooling in Harlow

Harlow's data centres, and the smaller rooms we cool

Charles Kao developed optical fibre data transmission on the eastern edge of Harlow, at the site Nortel later occupied, and the Kao Data campus on London Road is a £200m development using indirect evaporative cooling. Places like that employ their own engineers. We work at the other end of the scale: the comms cupboard in an office, the small server room in a factory or surgery, the one nobody thinks about until it fails.

How much cooling does a small room need?

Begin with the electrical load, because a server drawing 900W is also a 900W heater. Total up each server, switch, router and storage box. Allow for lights, people, any sunny window and future growth. Your UPS may display the load directly, and that is the most useful figure you can send us.

What temperature should a server room be?

The widely used ASHRAE guideline recommends 18°C to 27°C where air enters the rack, and UPS batteries tend to prefer the cooler end. There is no prize for going lower. A room held at 18°C when the equipment would be fine at 24°C is only using more energy. Take readings at the rack front, because a wall controller can be several degrees out.

Can you use a standard office unit?

Sometimes, but the duty differs in three ways. It runs every day, so it wears faster. It must still cool in January, when highs at the Writtle climate station average about 8°C and frost is common, and some models will not run reliably in that. And nobody is in the room, so a failure on Friday night might go unseen until Monday. Ask about the low outdoor temperature limit, and add a separate temperature alarm whatever you choose.

Do you need back-up cooling?

You do if losing the room would stop the business. The usual answer is a second unit ready to take over, and two units can also alternate, sharing the wear and keeping cover during a service. At the very least, write down what happens in the first few hours. Portable units make a poor long-term plan, given the exhaust hose through a door and the tank to empty.