Green-Trust.Org

Let’s look at the typical Central Air Conditioner. You have an air handler and heat exchanger indoors, and a condenser sitting outside. Your house is hot, and you want to cool it down. The air conditioner pumps the heat from your hot house to the outdoors. But wait a minute. Why is your house hot? Because it’s hot outside! So why does the outside want the heat from your house when it’s already hot?

Let’s look at the typical air source heat pump. Looks like an air conditioner. It is, but it’s reversible. If it’s cold indoors, it pumps heat from the outside into the house. But wait a minute. Why is your house cold? Because it’s cold outside. Where is the heat going to come from? Many manufacturers put electric resistance heat strips in their units to make them more effective. And you thought this was going to save you money?

Enter the Ground Source Heat Pump. This expensive piece of machinery does a couple of things. When it’s hot indoors, it pumps the indoor heat into the relatively cooler ground. When it’s cold indoors, it pumps the heat from the relatively warmer ground indoors. The ground is always cooler than hot outdoor summer air, or warmer than cool outdoor winter air. This greatly increases the efficiency of the process, and no more electrical heating strips. A common secondary byproduct is domestic hot water.

Read more at http://www.igshpa.okstate.edu/geothermal/geothermal.htm