Do They Save Money and Energy?

July 11, 2009 | By admin |

Yes! No! Maybe! While heat pumps are generally much cheaper to run than resistive electric heaters and even oil or gas furnaces (due to high fuel prices), there are many factors to consider before making a purchase. A heat pump costs a lot of money up-front, and it can take several years to recover this initial cost. Additionally, bringing another piece of high technology into your house has other subjective costs, such as dedicating floor space, finding a window to use for the exhaust duct, adapting to new noises in the house, cleaning and maintaining the unit, and so forth. Read on to see an example of the potential cost savings, which will help you decide if the savings are compelling enough to outweigh the other issues.

Looking around at major on-line retailers, it seems most portable air conditioner and heat pump models provide 10,000 BTU/hr to 14,000 BTU/hr of heating capacity when running in heat pump mode. I will use a 12,000 BTU/hr model as an example. The manufacturer’s manual for this model says it uses 1090 Watts of power to pump 12,200 BTU/hr into the house. Using a handy Google search conversion tool , I find that 12,200 BTU/hr is about 3575 Watts. The fact that this heat pump uses only 1090 Watts from the wall outlet to pump 3575 Watts of heat into the house from outside shows exactly why heat pumps are generally so cost effective compared to other types of heaters and furnaces.

Relative to a traditional resistive electric heater (the kind that simply plugs in and gets hot), this particular heat pump provides 3575-1090=2485 Watts of “free” heat. The word “free” is in quotes, because we are not breaking any laws of physics, here! A heat pump simply uses a little electricity to pump a lot of heat from one place to another (outside of a house to the inside). A plain old electric heater takes that electricity and turns it directly into heat, instead of using that electricity to run a more efficient pump. Conveniently, the amount of this “free” heat can be used to calculate the pay-back period of the heat pump!

My power bill shows that one kilowatt-hour of electricity costs about $0.10. Therefore, 2485 Watts of “free” heat for one hour is worth about $0.25. In other words, it would cost an additional $0.25 to run an old-fashioned electric heater to get the same amount of heat into the house. If the portable heat pump runs several hours each day throughout a winter season to supplement an electric or gas furnace, for example, it can provide over a hundred dollars in savings each year (say, a $1.50 a day for 100 days). While usage varies greatly depending on climate and temperature settings, it is clear a portable heat pump would pay for itself within a few years.

A brief survey of customer reviews at retailer websites shows, however, that there can be drawbacks to portable heat pumps, such as noise and even leaks or other annoyances. The manufacturers do provide some warranty coverage, but maintaining and repairing another piece of technology can become a burden in an already busy household. This is why it really depends on personal circumstances whether a heat pump is a good purchase in addition to using an existing furnace or other electric heat source. Some people really love their portable heat pumps while a few clearly have had “buyer’s remorse,” so do your research and see if a pay-back period of three to four years fits into your budget and plans! Remember, after the pay-back period, the savings can mean more money in your pocket for other expenses!

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