Most server rooms we get called to are not cooled badly. They are cooled as though they were offices, which is a different thing and a much worse one. Comfort cooling and critical cooling look similar on the wall and behave nothing alike when something goes wrong. Here is what businesses get wrong, and why the same handful of mistakes keep turning up.
In this guide
Critical cooling is a different job
Comfort cooling exists to make people comfortable. It runs when the building is occupied, it is allowed to be approximately right, and if it stops on a Friday afternoon, people are warm and irritated until Monday. Unpleasant, but survivable.
Critical cooling exists to keep equipment alive. It runs constantly, all year, whether anyone is in the building or not, and it is not allowed to be approximately right. If it stops on a Friday afternoon and nobody notices, you do not have warm staff on Monday, you have a room full of equipment that has been cooking itself for two days and a business that cannot trade until you fix it.
The equipment on the wall might be similar. The brief is completely different, because the failure mode is. And this is not only a data centre problem. Plenty of ordinary Teesside businesses have a comms cupboard with a switch, a server and a UPS in it, quietly running the whole company. That room is critical whether or not anybody has ever called it that.
Mistake one: using a comfort system
Somebody put a standard wall mounted split in the comms room because it was cheap and the same thing they were fitting in the offices anyway. Sometimes that is fine, and we will say so.
But standard comfort equipment is designed around an assumption that it gets to rest. It expects a building that empties, a night that cools down, a winter where it barely runs. A server room gives it none of that. It asks for full output, continuously, in a small space with no windows, and kit asked to do a job it was not designed for wears out early.
So the question at design stage is not “will this cool the room today”, it is “is this equipment specified for continuous duty in this application”. Only one of those gets asked in a cheap quote.
Mistake two: forgetting it runs in January
A server room needs cooling in December. The heat comes from the equipment, not the weather, and the equipment does not care that it is cold outside. So the system has to reject heat when the outside air is near freezing, and standard comfort air conditioning is not necessarily designed to do that.
Run a system outside the conditions it was designed for and you get problems that look mysterious from the inside. Low ambient operation is a genuine design consideration, and one of the clearest tells that a room was specified by someone thinking of it as an office. If nobody asked how your system behaves on a frosty night in Billingham, it was probably not considered.
Mistake three: no resilience
Ask a simple question. If the air conditioning in your server room failed right now, what happens? If the answer is “the room gets hot and eventually things start shutting down”, you have a single point of failure sitting between your business and an outage. That may be an acceptable risk, and plenty of small businesses look at it honestly and decide it is. But it should be a decision somebody made, not something you find out during the incident.
All mechanical equipment fails eventually, not because it is bad but because it is mechanical. Maintenance makes that rarer and better signposted. It does not get you to never. If never matters, that is a resilience question, and resilience is designed in, not bolted on afterwards.
Which is why the standard answer is two smaller units rather than one big one. Two systems, each able to hold the room on its own, means a failure leaves the room up. You get a repair booked as a job rather than an emergency, in daylight, at a normal price, with the right part ordered instead of whatever can be got today. Where they alternate rather than one sitting idle, both get exercised and you find out a unit has a problem while the other is covering for it. A standby that has not run for two years is not a standby, it is a hope.
The honest caveat: this costs more up front and more to maintain. We can tell you what it costs. Only you know what it saves.
Mistake four: nobody finds out in time
This might be the most important item on the list, and frequently the cheapest to fix. A server room is a room nobody goes into. So when the cooling fails at eight on a Saturday evening, there is nobody to notice. The room heats up over hours, and the first anyone knows is when something shuts down, or when the first person through the door on Monday feels the wall of heat.
The fix is monitoring and alarms that reach an actual human, not a light on a panel in a room nobody is in. And the alarm has to go somewhere useful: an alert into an inbox nobody reads at the weekend is not monitoring, it is documentation of the failure. Then test it once, because an untested alarm is a guess.
Mistake five: sizing for today
Server rooms grow. Nobody ever took equipment out of one and left it emptier than they found it. A room sized precisely for the kit in it on the day of the survey will be undersized within a few years, because a server gets added, then a switch, then the thing that was supposed to be temporary. Nobody re-thinks the cooling when they rack another box, because racking a box takes ten minutes and does not feel like a decision about air conditioning. So the survey conversation has to be about where you are going, not only where you are.
Mistake six: the room itself
Cooling is only half the picture. The room around it does a lot of work, or a lot of damage.
- Airflow to the equipment. Cold air has to reach the front of the kit and hot exhaust has to get away. A system blowing cold air at the back of a rack while the fans pull hot air from the wrong side is technically cooling the room and doing very little for the equipment.
- Stuff in the way. Comms rooms attract boxes, spare monitors and the chair nobody wants. All of it blocks airflow, and none of it was there at commissioning.
- Doors and gaps. A room leaking cold air into a corridor makes the system work permanently for nothing.
- Heat from elsewhere. A cupboard on a sunny external wall, or backing onto a plant room, has a heat load nothing to do with the servers.
- Drainage. Condensate needs to go somewhere that is not onto electrical equipment. Water and racks are a bad combination, and the time to think about the route is before the unit goes on the wall above them.
Mistake seven: off the maintenance schedule
The system in your most critical room is frequently the one nobody services, precisely because it is out of sight. That is the wrong way round. A unit running continuously fills its filters faster than one that runs seasonally, and a restricted filter makes it work harder for less. Coils get dirty. Drains block. Refrigerant escapes slowly and nothing announces it, so performance drifts down for months, and on a system with no headroom that drift is what turns a warm week into an incident.
It matters for your paperwork too. The comms cupboard unit is the single most commonly forgotten system when businesses audit their F-Gas compliance, because it is not in an office and nobody thinks of it as air conditioning. It holds refrigerant like everything else and the duties apply to it like everything else. Our F-Gas compliance checklist goes through how to find the ones you have missed.
If reading this has made you think about a cupboard in your building, that is worth acting on while nothing is wrong. We will come and look, tell you honestly whether it is fit for what it is doing, and tell you if it is fine, because sometimes it is. We are based on North Ormsby Road in Middlesbrough and cover roughly twenty miles of Teesside: Stockton on Tees, Thornaby, Billingham, Norton, Yarm, Eaglescliffe, Ingleby Barwick, Redcar, Marske, Saltburn, Guisborough, Marton, Hartlepool, Peterlee and Darlington. We offer planned maintenance and rapid-response cover on single sites and multi-site portfolios, on any make, model or age of equipment. Site surveys are free. Ring us on 01642 680 873.
