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How much heat is in that cupboard?
Comms and server rooms run all year and do not care what the season is. This turns the electrical load into a cooling figure and says what the arrangement around it should look like.
The check
A first estimate, not a design. It takes the electrical load as heat, adds a margin, and ignores the building envelope, lighting, people and UPS losses — all of which a real calculation includes. It runs in your browser and nothing is sent anywhere.
Heat to remove
10,200 BTU/h about 1 ton of cooling, with a marginCooling tied to the building schedule is the most common arrangement and the most common cause of a Monday morning call. The equipment does not stop at seven in the evening, and neither should its cooling.
- Either put the room on its own dedicated cooling, or take that zone out of the schedule so it runs continuously.
- Check what happens on a public holiday and during a heating-only changeover — that is when rooms cook.
- A temperature alarm is cheap and tells you before the equipment does.
A dedicated unit running continuously is the right shape. What is worth checking is whether it has been sized for the load that is in the room now rather than the load that was there when it was fitted.
- Compare the figure above with the capacity of what is installed; racks grow and units do not.
- Service it on a schedule — a filter nobody changes is how a dedicated unit quietly stops coping.
- Ask what happens if it fails: an alarm, a spare, or a plan beats discovering it at 30°C.
A grille, a fan or a propped door moves heat into the next room rather than out of the building. It works until the weather is warm or the door is closed by somebody tidying up.
- This is the arrangement most likely to produce a failure on the first hot weekend.
- A small dedicated unit sized to the figure above is usually the whole fix.
- If that is not possible, at least get a temperature alarm in there before the summer.
Where the room matters this much, capacity is not the only question. Redundancy, alarms and what happens during a power interruption all need deciding — and that is a design conversation rather than a figure from a slider.
Worth a temperature alarm. At this level of disruption, knowing early is worth more than the last degree of capacity.
Four things the slider cannot see
- Airflow in the roomCold air that never reaches the front of a rack does nothing. Layout matters as much as capacity in a small room.
- Where the heat goesA unit rejecting heat into a ceiling void or a corridor moves the problem rather than solving it.
- CondensateA cooling unit in a room full of electronics has to drain somewhere safe, with a float switch that shuts it down rather than overflowing.
- WinterSmall rooms still need cooling in January. Equipment that cannot run in low outdoor temperatures is a common and expensive surprise.
