OK folks, with the summer heat arriving, it's time to discuss air conditioning. There is a major misconception I'd like to clear up.

Let's review how air conditioning works. Basically, an air conditioner is a heat pump.

Using a few important thermodynamic principles, air conditioners are machines that move heat from one area to another. Typically, they move the heat from inside to outside.

The part of the air conditioner that gets cold in this process is know as the evaporator coil. Warm air from inside blows over the evaporator coil. The heat goes in and gets pumped outside and the cold air returns inside.

Fairly straightforward, no? Air conditioners really only work at one speed. When they are on, the pump heat out. When they are off, they don't do anything.

Here's where people get into trouble.

Modern electronics in thermostats and car air conditioners now allow people to dial in the temperature they want. The air conditioner (or heater) is turned on or off to adjust for the desired temperature.

It seems people think that if they turn the knob way down that the air conditioner will work much better. Typically, you see people turning the thermostat as low as it will go to get it cold. This does nothing to help the cooling.

Turn the dial or knob to the temperature you want and leave it alone.

There are a few cases where there you can have variable air speeds blowing over the evaporator coils. This is what 'Max AC' is if you see it in your car. Maximum airflow.

Guess what, your thermostat understands if it has variable airflow and uses it when it makes best sense. Believe it or not, the people that design air conditioners know more about how to make air conditioners work than you do.

So, please people, don't turn that dial down to sixty degrees unless you work in a meat locker.

Posted by michael at June 28, 2004 09:52 PM