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There is a cupboard full of equipment and it is cooking
Five kinds of room with something hot in it, crossed with the four situations they turn up in. What a comfort system can and cannot do for equipment, and the one case where this is not our trade at all.
Three things that apply to every answer below
- The heat load is printed on the equipment, so nobody needs to guess it
Electrical equipment converts very nearly all the power it draws into heat. If a rack pulls a kilowatt, it is a one-kilowatt heater standing in your cupboard, all day, every day. Add up the labels, or read the figure off a power distribution unit if there is one, and you have the load to within a few per cent. This is the easiest load in the whole trade to get right and one of the most frequently estimated by eye.
- A comfort system is designed to stop when the room is comfortable
Which is exactly the wrong behaviour for a room whose occupant is a machine. The building system shuts down at night and at weekends, and it modulates to a setpoint that assumes people. That single mismatch is the cause of about half the complaints on this page, and it is why a small dedicated unit is so often the right answer rather than a change to the main system.
- If there is a number, it is not ours
Where equipment or stock must be kept within a range, that range comes from the manufacturer, the supplier, or an insurer. We will ask for it in writing, design to it and measure against it. What we will not do is supply one, and a contractor who tells you what temperature your equipment needs without asking anybody is guessing on your behalf.
Work out what the room actually needs
Pick what is in the room and pick the situation. Every answer below is on this page whether you pick anything or not — the picker only narrows it down.
There is a real line between a room that gets uncomfortably warm and a room where a temperature excursion is a business event, and the second one needs a different discipline. What a room with an uptime requirement actually needs is redundancy, so a single failure does not take the room out; monitoring and an alarm that reaches a human at three in the morning; a maintenance regime built around never stopping, including the ability to service one unit while another runs; and frequently a different class of equipment altogether, specified in kilowatts of sensible heat rather than in tons of comfort cooling. None of that is a comfort contractor’s work, and a firm that sells you a single wall-mounted unit for such a room has sold you something that will work beautifully until the day it does not. What we will do is tell you this at the first visit, measure the load properly so you have a real figure to give a specialist, and be perfectly happy to do the comfort cooling in the rest of the building. What we will not do is quote it. That refusal costs us a job roughly twice a year and it is the correct answer every time.
Add up the watts first. Half of these cupboards do not need cooling at all.
A couple of switches and a router in a cupboard may be producing less heat than a person does, and the answer is frequently a vent, a grille in the door and somewhere for the warm air to go rather than any equipment at all. The label figures tell you which situation you are in, in ten minutes.
What to look at, cheapest first
- Ventilation. A louvred door and a path for warm air to leave at the top is the whole answer for a small load in a room that is otherwise conditioned. It costs almost nothing and it is very often skipped in favour of buying something.
- Where the cupboard is. A comms cupboard on an external west wall and one in the middle of a building are different problems. Moving the equipment is occasionally cheaper than cooling it.
- A transfer path. Extracting warm air from the cupboard into a conditioned space, with a small fan and a grille, uses the building’s existing cooling rather than adding more.
- A dedicated unit. Right where the load is genuinely significant or the cupboard is isolated from the conditioned space. Sized from the watts, not from the floor area.
One thing worth measuring before anything is bought: what the temperature in there actually is, logged over a week including the weekend. A cupboard that is fine on a Tuesday and thirty-five degrees on a Sunday afternoon is telling you the building system is the problem, not the capacity.
Most home offices need a return path and an open door, not a second system.
A converted bedroom with a desk and several machines is a real load and it is usually being starved rather than under-cooled. The room gets supply air, the door is shut for eight hours, the air cannot get back out, and the airflow collapses. That is a twenty-minute fix, not a project.
In order, and the last one is the expensive one
- A way for air to leave the room. A transfer grille, an undercut door, or a return in the room itself. This is the single commonest finding and the cheapest.
- The supply airflow measured at the register, against what the room now needs with the equipment in it. It is frequently less than half.
- Solar control if the room faces west, which in this valley is worth more than anything mechanical for the hours that actually matter.
- A dedicated head where the load is genuinely high, the room is used outside the hours the house system runs, or the house has no duct route to that room.
Worth saying plainly: a room with a couple of laptops and a monitor is not an equipment room. A room with a workstation, three monitors, a small rack and a printer might be, and the labels will tell you which you have.
Get the temperature and humidity range from whoever owns the equipment, in writing, first.
A small server or comms room is a straightforward load calculation once somebody has said what the room has to hold. Without that number, everything that follows is a guess, and it is the number that decides whether this is a comfort job or a specialist one.
What a small comms room usually needs
A dedicated unit that runs on its own schedule, independent of the building system, all year including weekends. Nearly every failure we are called to in these rooms is a room served by a system that switched itself off on Friday evening.
Sizing from the electrical load, in kilowatts, plus an allowance for the fabric. The floor area is almost irrelevant.
Somewhere for the condensate to go that is not over the equipment, and a float switch that shuts the unit down rather than a pan that overflows into a rack. This is the detail that turns a small job into a disaster and it is the one most often skimped.
A thermometer somebody actually looks at. At minimum. If the room matters enough to cool, it matters enough to notice when the cooling stops, and a basic monitored sensor costs very little.
And honestly: if the answer to “what happens if this room is warm for a day” is anything other than “we shrug”, read the note at the top of this page before you go further.
Extract at the source. Cooling a room that a machine is heating is paying twice.
Where a process, an oven, a compressor or a piece of test equipment is producing the heat, taking it away at the point it is made is cheaper and more effective than removing it from the room afterwards. This holds almost without exception and it is the first thing to price.
Three measurements, and they are not the comfort ones
- Air temperature at the working position, logged rather than sampled, at the hours the work actually happens.
- Radiant heat near anything hot. A person beside a furnace or a press is being heated by radiation, and the air temperature describes none of it. It needs measuring as its own quantity.
- The equipment’s own load, from the labels, so that the extraction can be sized against something real.
The usual answers are a canopy or a local extract over the source, screening or insulation of hot surfaces, directed air movement at the work positions, and whole-room cooling last if at all.
The limit, said clearly: where extraction is dealing with fumes, dust, solvent vapour or anything hazardous rather than with heat, that is an industrial hygiene and laboratory ventilation question. We will tell you and we will not take it on, because getting it slightly wrong there is a different order of consequence.
The number comes from the product. Then measure where the goods actually sit, not where you walk.
Stock with a temperature or humidity requirement is governed by a specification from the manufacturer, the supplier or an insurer, and that specification is the whole brief. Once it exists, the job is ordinary — and the measurement has to be taken at the goods, which are usually high on a rack or inside a cabinet.
What changes when it is stock rather than people
Stability matters more than the absolute figure. A store that swings between two extremes twice a day is harder on most products than one that sits steadily near the top of the range. That is a controls and a fabric question as much as a capacity one.
Humidity is frequently the real requirement and is frequently the one nobody mentioned. It is measurable and it changes the equipment.
Logging is the deliverable. If a product has a specification, somebody will eventually ask whether it was met, and a record with dates is worth a great deal more than a thermostat setting.
And where it is refrigeration rather than comfort cooling — cold rooms, chilled or frozen storage, display cases — that is a different trade and we will say so in the first minute rather than attend and discover it.
In a house
Then the cheap answers are much more likely to be the right ones, and it is worth working through them before anybody quotes equipment. A transfer grille, a measured register, a door left ajar and solar control will solve a majority of home-office complaints for very little.
Where a dedicated unit is right, a single ductless head is almost always the answer: it runs independently of the house schedule, it can be sited where the line set is serviceable, and it does not disturb the rest of the system.
Two practical notes for a house. Noise matters more here than anywhere — the room is next to a bedroom and the unit may run at night, so siting and the sound figure are part of the specification, not an afterthought. And the condensate has to have somewhere to go that does not involve a pump in a cupboard nobody looks at.
In a leased suite
Then the first question is not mechanical. Anything mounted on an external wall, penetrating the fabric or placed on the roof needs the landlord’s consent, and a dedicated unit for an equipment room is all three of those things.
What to establish before design: whether an outdoor unit can be sited at all and where; whether the lease requires reinstatement at the end of the term, which changes the economics considerably; and who owns the equipment when you leave.
Where consent is unlikely, the alternatives are real and worth pricing: extracting the heat into a conditioned common space, changing the building system’s schedule so that it does not shut down on the room, or relocating the equipment to a better part of the suite.
We will not interpret your lease and we will not approach a landlord on your behalf. We will produce a drawing, the dimensions, the published sound figures and the electrical requirement, which is what a consent application needs.
In a building you own
Then the whole range is open, and the useful thing is to decide the standard once rather than per room. Buildings like this usually accumulate equipment rooms one at a time, each solved by whoever was available, and end up with five different arrangements and no records.
Worth doing once: a list of every room with an equipment load, the watts in each, what temperature it is expected to hold and who said so, and how it is currently served. It takes a day and it is the document that makes every subsequent decision cheap.
And worth deciding once: whether these rooms come off the building system or have their own units. Owning the building means you can change the schedule, add a zone, or run a separate circuit — options a tenant does not have.
It has an uptime requirement
Read the note above, because it is the substance and it is the one firm answer on this page.
What we can usefully do for you even so: measure the load properly, in kilowatts, so that whoever you do engage is quoting against a real figure rather than a floor area; log the room’s current temperature so there is a baseline; and tell you plainly whether what is in there now is close to adequate or nowhere near it.
That measurement is worth having before you talk to a specialist, and it is a small job. It is also the point at which a good many people discover the room is not as critical as they had assumed, which is a perfectly good outcome and saves a great deal of money.
Where this page stops
We will add up the equipment load from the labels, log the room over a week, price the cheap answers before the expensive ones, and install a dedicated system where one is genuinely the right answer — sized from watts, running on its own schedule, with the condensate and the float switch done properly.
We will not invent a temperature specification, quote a room with a real uptime requirement, take on fume hoods, containment or cleanroom certification, or interpret a lease. If a room matters enough to cool, it matters enough to monitor, and we will say that even when nobody asked.