Q – I have come up with a great way to save energy this summer.  My hvac unit is a 3 ton unit.  By upgrading to a 6 or 7 ton unit I should be able to cool my house twice as quick, thus saving energy.

I realize it will cost some money to upgrade.  Is this a wise move?

Ted in Vinings.


A – This is one of those things that sounds great, but in actual practice, not so much.

True, a larger unit will cool your house faster.  But in this instance, faster is not better.

First of all, it’s your air conditioners job is to cool your air, but its other job, and in my opinion it's real job, is to keep the moisture (humidity) out of your house.  Think of your a/c as a whole house dehumidifier.

We all know that too much (over 60%) humidity in a house can and will lead to problems such as mold and mildew.  Your air conditioner running on a normal setting of, say, 76 degrees will run long enough to keep your humidity in check.

But by using a larger unit, the unit will cool faster but not run long enough to keep the humidity in your house at a good level.  Its run time will simply be too short to be an effective humidity controller.

Plus, unless you plan on insulating your house like a meat locker, you will lose a lot of that cool air in a hurry, thereby forcing your system to run more which will defeat your whole purpose.

So make sure you have a high efficiency system, and then spend the rest of your dough on better insulation.