Can you run your central air conditioner at 73 degrees in the winter to use as heat?

Great question. And the answer is unfortunately, no, but you are on the right track. An air conditioner is only capable of removing the heat from inside your home and transferring it outside.

A heat pump is a different story. A heat pump is essentially an air conditioner that can run backwards as well. A heat pump actually pulls the heat out of the cold outside air and transfer it into your house. Even cold air has heat in it. This is a bit counter-intuitive, but your refrigerator does the same thing.

Heat pumps lose their efficiency as it gets colder and there is less heat in the freezing outdoor air. Some will work to very cold temperatures (below zero), but most lose their efficiency at 20-25 degrees. At that point heat pumps use resistance heating (like a hair dryer) which is VERY expensive.

If you live in a warmer climate, a heat pump is very efficient and often a good choice. If you live in a colder climate, they are still effective, but you may have to buy a more expensive model.