Ways to cool a computer room

Ways to cool a room

When your Small Office / Home Office (SOHO) is too hot

If your office, bedroom, den, or server room has a few computers in it, you likely have a room that is warmer than the rest of the house in Summer. If you turn the thermostat down, the office gets cooler but the rest of the house is too cold and the electric bill gets a lot higher. Here are some things you can do to make it more comfortable.

Identify the problem

The following list assumes you have control of the thermostat (t-stat) and that the Air Conditioner (AC) is strong enough to cool the other rooms in the house down. You must identify your condition to get the best results.

Problem 1- Cyclic comfort: The room cools down fine when the AC comes on, but it quickly heats up after it turns off. There is a long, uncomfortable time span waiting for the AC to come back on.

Problem 2- Never cool: The room is always warmer than the house, even when the AC has been running for a while.

Solving Problem 1- Cyclic comfort

The cause of this problem is the t-stat does not know that it is getting hot in your office. The rest of the house slowly warms while the office warms quickly. So there is a delay (lag) in the t-stat response.

SOLUTION 1.1 The fast, cheap, and easy way to fix Cyclic Comfort is to switch the fan from Auto to On. The air circulation will bring the warmed office air to the t-stat sooner, reducing the lag time. The down sides of this are

The fan is using more electricity
The humidity levels will fluctuate (from re-evaporation of condensation from the air hander coils) .
In some situations the air flowing through ducts in the attic may bring more heat inside.

Result: Works so-so, best in climates with a few hot days. Not a long term fix, but better than nothing.

SOLUTION 1.2 Move or add a thermostat to the office. Having the t-stat in the same room as you are in allows it to respond to the same temperature as you are experiencing, yielding a comfortable room. I bought a t-stat similar in features to the existing one in my house for <$50 (although for maximum comfort I should have bought the $100 'intelligent' adaptive type). While at HomeDepot./Lowes I picked up a coil of real t-stat wire. Then I bought an A/B loudspeaker switch box from Radio Shack for $10. An hour of wall fishing / drywall anchoring / wiring had the t-stat professionally attached to my office wall. A half hour of inserting the A/B switch into the existing t-stat wire and it was done. Now I could choose to use the original t-stat or the new t-stat. I don't think you can run them in parallel (anyone know for sure?) I'm not sure what Winter has in store, perhaps the new t-stat location will be ok. The switch is probably not "to code" in many cities.

Result: Was it worth it? Yes. The effect was instant and satisfying. The AC comes on more often but stays on for shorter periods of time. I decided to complete the project by rebalancing the air flow a tad.

Solving Problem 2- Never cool

The cause of this problem is the AC air flow through the room is not capable of removing the heat put into the room. The heat put into the room is mainly from the occupants, the hardware devices (PC's, monitors, etc), and the heat coming through the external walls and windows. To solve the problem you will need some combination of these 3 things;

reduce the heat input,
lower the air temperature coming out of the registers (duct exits), and/or
increase the flow of air coming out of the registers.

These solutions assume you have already tried leaving the room door open.

SOLUTION 2.1 Some fast, cheap, and easy ways to reduce the heat input into your office;

Remove or turn off unneeded hardware.
Make sure CRT monitors go into standby quickly.
Put some of your equipment in another room or closet. Owners of WLANS can do it easily. I put a PC in a spare-room closet adjacent to my desk. Just cut a hole between rooms at the level of the wall outlets, trim it with wall plates, pass the cables through and the heat source (the PC) is no longer heating the office. Plus its quieter.
Close the window shades during the day. (Duh)

Results: May solve the easy cases. Best when used in combination with other solutions.

SOLUTION 2.2 To lower the air temperature coming out of the registers you are mainly limited to calling an AC tech to check your system (and presumably add Freon). Modern homes have insulated ducts. If yours is older you may be able to insulate the duct between the air handler and the register. Lastly, you could by a new AC unit.

Results: An AC house call is in order 'just to be sure' if you haven't had an inspection in 2+ years. I had the tech come (under warranty) when one of my homes was 2 months old, it didn't solve anything as they had been filled correctly to begin with.

SOLUTION 2.3 To increase the flow of air coming out of the registers do some airflow balancing. This makes more air come out of the register, and more air passing through the office to carry heat out the door.

Cautions: Obviously, adjusting anything as important as your homes AC system has a lot of risk to it. You could be out some serious money if you mess it up. Climbing in an attic has physical risk as well. I'm only saying what I did. If you don't have a clue, don't even try this. Proceed at your own risk.

The air hander has several tubes that carry air from the fan to the rooms. In one or more places there are dampers (butterfly valves) with handles sticking out. To increase the air flow to the office, I located the dampers(s) between the air handler and the room , and opened them up to get maximum flow. Simultaneously, I found some other rooms that need a little less flow and closed those down a bit. I wanted to have roughly the same amount of backpressure as the unit started with (assuming the home builder/ AC sub did it right).

Just so you know, the AC sub contractor's engineer creates a plan for each model of home. The plan estimates heat load in the rooms and shows a desired CFM for each register. The AC tech uses a flow meter to measure the flow out of each register and adjusts either the butterfly valves or the registers vents to achieved the right flow rate. Often the engineer does not add the load of several high end PC's and thus the calculations are off. You may be able to request a copy.

After doing a change, you need to keep an eye on the entire house for a few days making sure all of stays comfortable. Also, you need to note the original positions for winter. When the heat is on some parts of the house may get too cold. Your S.O. will alert you to this condition.

Results: This was worth it! The extra air flow really makes a difference. Best of all it didn't cost anything, just some time and effort.

SOLUTION 2.4 To increase the flow of air coming into your room, add another register (and an air duct of course). I had an AC tech do this in one of my houses. I had him put it right above where I sit. It's been a while, but I think it costs about $400.

Results: Feels great to have it blowing over me when the AC is on. It was the correct solution for that office.

SOLUTION 2.5 To increase the flow of air coming into your room, add a duct flow booster fan or register booster fan.

Results: I have not tried it, but sounds good if you can handle the extra power wiring..

SOLUTION 2.6 To increase the flow of air coming into your room, add an uptake register (the inlet where the air filter goes). This requires a fair amount of mechanical work but would allow you to keep the office door closed without affecting cooling.

Results: I have not tried it, but sounds good if you can afford it.

Author's comment- I collected these thoughts after moving into a few new homes. With several of us working on computers in one room they always needed changes. I figured many people ran into the same situation so these notes were posted. Hope it helps.

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