How to choose a heat pump
1. Temperature. First of all, you must come to terms with what you can expect from your heat pump. What is the climate in your region? Does weather remain pretty temperate, or do temperatures swing violently in either direction during a year? A heat pump will not suffice in freezing and the most extremely cold weather. For much of the year, the heat pump will work like a charm for you, but when the temperatures drop into the deep freezing dead of winter, you really need a backup heating source. If you can afford both heat pump and gas furnace, this setup makes the most sense; the gas furnace will be most efficient below 30 degrees Fahrenheit, while above that temperature (until around 70 degrees) the heat pump will work best.
2. Air-source. We’re all fairly familiar with the function of air conditioners. An air-to-air heat pump works basically the same way, except that it can switch from providing cold to providing heat (these heat pumps each have a valve that determines the direction that the refrigerant flows within the device).
Air-source heat pumps won’t require the contractors to dig into your yard and bury anything, as will the ground-source heat pumps. (Who knows what they might dig up?) However, you’ll have to deal with the fact that the heat pump extends out into the cold, where frost can build up. Because the frost hampers the ability of the heat pump to provide heat, the heat pump has to occasionally divert its attention to thawing itself out! This disrupts the flow of heat into your house until the heat pump has satisfactorily thawed itself.
3. Ground-source. Ground-source heat pumps serve the same purpose, but instead of moving heat from the outside air into your home, they move heat from the ground (earth) into your home in cold months, and transfer heat from your house back into the ground in the summer. Since earth temperature is pretty steady, and warmer in winter months than the outside air, performance can remain closer to the same level year-round.
Though digging (vertically or horizontally, depending upon available space) will be required to install the piping of the heat pump underground, these heat pumps will not suffer the frost frustration that air-source heat pumps have to endure; the whole heat pump unit, minus the underground piping, is actually indoors.
4. SEER and HSPF Ratings. Consider these ratings when choosing a heat pump. SEER (Seasonal Energy Efficiency Rating) refers to the efficiency of the heat pump acting as an air conditioner, while HSPF (Heating Seasonal Performance Factor) tells you how efficient the heat pump works as a heating unit. If you can, choose the heat pump that is most efficient.
5. Size. You could probably get away with heating and cooling exclusively on a heat pump, but you’d be better off relieving your heat pump with a different heat source in the coldest parts of the year; heat pumps aren’t as efficient in extreme cold.
