Many people prefer to have a heat pump.
With a heat pump, you do not need to have a separate AC system and a heater, the heat pump actually provides both heating and cooling capabilities.
During colder temperatures a heat pump will extract heat from the air outside and pump it inside. This means that they use much less energy than even the most energy efficient furnaces.
Unfortunately however, heat pumps work best at temperatures above 40 degrees.
When it gets very cold and the air temperature falls below 40 degrees, the unit can freeze up. When this happens the system has to defrost itself. During a defrost cycle the air conditioning has to run in order to melt the ice, and the backup electric heater will turn on so cold air is not blown into the home. So basically you have AC and heat working at the same time which isn't all that efficient.
The way to avoid this situation is to go ahead and turn the heat on before it gets that cold. On most thermostats this is listed as EM Heat (Emergency Heat) When a thermostat is set to this, only the heat will turn on when the temperature drops.
Sean McCutcheon's Air Conditioning and Heating, Inc. advises that you test your electric heat before the temperature gets very cold. This way you know that you will have heat on those cold nights.
Most people never think to make sure the heat is working properly, and every year this results in great numbers of people calling AC repair companies for emergency service calls. There just aren't enough AC techs to handle these calls and some people go days without heat.
Another great idea is to sign up for a preventative maintenance program.
Your AC System will be completely checked every spring and fall so you will have peace of mind knowing it will heat when it needs to. Also, with a maintenance agreement, if you ever do need a repair, you will get priority as a preferred customer.