Choosing A Heat Pump
Heat pumps sound like a great way to heat (and cool) your home. Simply by taking advantage of the heat that exists in the air or the ground, even during the winter you can save energy, money and protect the environment, what's not to like? If you think a heat pump might be in your future, here's some things to consider before you buy one.
Where do you live?
The climate in your location will have a major impact on whether a heat pump will actually work for you. If you live in an area with dramatic swings in temperature or the temperature falls down to way below zero, a heat pump alone won't be able to heat your home - there simply isn't enough heat in the air or ground to heat your entire home. You will need some form of supplemental heat for your home.
Consider the predominant source of heat fuel in your region?
Natural gas when used for heating is substantially more efficient and less expensive than electricity. If you live in an area where natural gas is readily available, you should carefully evaluate and compare the costs of a natural gas heating system versus a heat pump using electricity. However, if electric heating or even oil are the predominant sources of home heating in your region, it's likely a heat pump could provide you with both dollar and energy savings over its life.
What kind of heat pump - air source or ground source?
An air source heat pump is very similar to a central air conditioner, except it can provide both heat in the winter and cooling in the summer. Air source heat pumps have an advantage over ground source installations since they don't require any digging or excavation of your yard. However, again similar ton air conditioner, air source heat pumps do make noise when operating.
Another consideration with air source heat pumps is that during cold spells, some designs can frost up. When that happens, the unit needs its heat to defrost itself rather than heat your home.
If you are considering an air source unit look for one with a 'demand-defrost control' to minimize the defrost cycle.
Geothermal heat pumps on the other hand, have the heat exchanger inside the house so won't ever frost up and are silent while operating.
However, the cost of installation can be substantial due to the digging and excavation necessary and depending on the underlying structure of your land the installation costs can be substantial.
Don't forget the energy efficiency of the units
Since heat pumps act as both air conditioners and heat sources you should consider both their SEER (Seasonal Energy Efficiency Ratings - same as an air conditioner) and their HSPF (Heating Seasonal Performance Factor rating).
According to the US Department of Energy, federal efficiency standards require that conventional heat pumps have an HSPF rating of at least 6.8 and a SEER rating of at least 10.0. The most efficient air source heat pumps have an HSPF rating between 9.0 and 10.0 and a SEER above 14 or so.
Converting to a heat pump?
A heat pump installed in an existing home may require the existing duct be expanded since heat pumps generally need larger sized than other central heating systems.
Finally, no matter what type of heat pump you choose, be sure you have a reliable, trained contractor do the work. You can find qualified installers by contacting either the Geothermal Heat Pump Consortium (http://www.geoexchange.org/), the International Ground Source Heat Pump Association (http://www.igshpa.okstate.edu/index.htm) or in some areas, your local utility company.
