Air conditioning that closet?

You might want to rethink that...

It's not at all unusual for clients to have their home theater equipment installed in a new or existing closet. Located in or just outside the theater, it's a logical place to put audio-video electronics, whether in a rack or on shelves. But - it may not be that easy. Whether it's "coat" or "walk-in" size, some thought has to be given to ventilation, and this frequently leads to the idea of using air conditioning.

One way this can be done is to run a cold air supply or return duct, or both, into the closet. While this is one of those "seemed like a good idea at the time..." ideas, it may not be the best way - or even a good way - to solve the problem. There are several problems associated with using air conditioning to cool an equipment closet.

First, there is the question of wintertime operation. In most parts of the country, the system that delivers cold air in July delivers hot air in January because the same air handling and ductwork is used for both cooling AND heating the home, depending on the season. The damper in the closet (if one was installed) can be closed at the beginning of the heating season, of course, but --

1. The owner has to remember to do this, and

2. The closet now has no ventilation.

A second problem that goes along with air conditioning the equipment closet concerns temperature control. Unless the refrigeration system is dedicated to that closet, it is likely to be controlled by a thermostat located in the theater or elsewhere. The cooling will stop when the temperature at the thermostat is below the set temperature, but the amplifiers, cable box, satellite receiver, etc., in the closet will still be on, building up heat.

Locating the thermostat in the closet can solve that problem, but will cause the refrigeration system to run longer than necessary to cool the theater itself, resulting in frostbitten clients, not to mention a high electric bill!

Getting back to the details of providing air conditioning to a closet, there are several ways to do this wrong. Having just a cold air supply duct without a way of recirculating the warmed air will keep any cold air from entering the closet; there must be either a return duct in the closet or a way for the air to recirculate passively, such as the use of a louvered door. Having just a return duct in the closet without a way for cool air from the surrounding area to enter is another mistake. The closet has to be able to "inhale" AND "exhale" for effective cooling.

Perhaps the single biggest problem of using air conditioning to cool any but the largest home theater installations is the cost involved. The first cost of running ductwork (especially in a retrofit situation), or increasing the size of the planned system (in new construction) can be substantial. Then there's the never-going-to-stop cost of operation. Month after month, even in the dead of Winter, the owner will be paying for power to run the refrigeration -- not very green!

This is just one of the considerations that must be explored when designing a system. We, as Total System Integrators, are in the best position to evaluate the interaction of the entire home’s system’s heat generation and removal requirements.