A heat pump is a device that acts as an air conditioner in the summer, by ejecting heat from the inside to the outside, and as a heater in the winter, by drawing heat into a home from outside. Heat pumps act as a single system used both for heating and cooling, while traditional split systems have two parts - an indoor furnace and an outdoor air conditioning compressor that work separately to heat and cool your home.
Technically speaking, heat pumps are vapor-compression refrigeration systems with both indoor and outdoor coils that act reversibly as condensers or evaporators - depending on whether they're needed for heating or cooling. The direction of heat transfer simply depends on the season.
Because heat pumps don't burn fuel, they are considered safer than a gas-powered furnace.
If you're going to use a heat pump for your heating and cooling needs, you need to carefully consider all the different models and options available. The main complaint about heat pumps is their inability to function well over long periods of intense cold.
When choosing a heat pump, there are two measurements you need to consider. Looking at a heat pump as a source of heating, you need to check its heating season performance factor (HSPF). This is a ratio of the available heating output in comparison to the average consumption in your area, and will allow you to judge how well the heat pump will perform when you need it.
If you're considering a heat pump as a cooling system for your home, you need to check the seasonal energy efficiency ratio (SEER). Similar to the HSPF, this is a ratio of the available cooling output in comparison to the average consumer's needs, and will allow you to gauge the heat pump's performance abilities.
The higher these ratios, the more efficiently your heat pump will perform while keeping your house warm or cool.
National standards for heat pumps require a minimum of 7.7 HSPF and 13 SEER, so the higher your heat pump's ratios in comparison to these numbers, the better.
Prices for heat pumps can vary widely depending on the ratios at which they perform.