Heat pumps are becoming a more common alternative to central air conditioners no matter what type of existing heating system you have. This is because a heat pump can also heat, as well as cool, your house efficiently. The cost of electricity for heating and cooling a house, although it gradually increases as most prices do over time, is much less volatile than natural gas, oil, or propane.
A standard air-source heat pump is basically a central air conditioner with a few extra parts. The outdoor unit looks exactly like a central air conditioner. It is called a heat pump because it literally pumps heat out of your house (cooling mode) or into your house (heating mode) to or from the outdoor air around the outdoor compressor/condenser unit.
During the summer in the cooling mode, it draws heat from the indoor air as it passes through the indoor evaporator coils. Through a refrigeration cycle identical to an air conditioner, it expels this heat outdoors. The cooling efficiency is rated by its SEER (seasonal energy efficiency ratio).
During the winter, a reversing valve inside the heat pump outdoor unit switches position. This reverses the flow of the refrigerant. Instead of running the cool refrigerant through the indoor coil, it runs the hot refrigerant indoors.
The cold refrigerant is run outdoors where it draws heat from the outdoors. Since the refrigerant is colder than the outdoor air, it absorbs heat even though the outdoor air may feel cold to you. Heating efficiency is rated by HSPF (heating seasonal performance factor).
Even if your indoor air handler seems to be working well, it should be replaced with one compatible with the new efficient outdoor unit.
No matter what type of new heat pump you select, make sure your duct system is compatible with it. There should typically be from 400 to 500 CFM (cubic feet per minute) of airflow per ton of cooling through the unit for the best efficiency. Your old duct system may have to be modified.
Geothermal heat pumps aren’t for everyone
A geothermal heat pump, which is different from a standard air-source heat pump, is one of the most energy-efficient heating and cooling systems for any climate. Even though it provides a good long-term payback over its life on the investment, particularly in very hot or cold climates, the initial installation costs are considerably higher than for standard air-source models. Also, depending on the yard and soil type, it may not be applicable for every house.