Heat pumps are popular and efficient

Q: I hear people install a heat pump instead of a furnace and air conditioners. I can't afford a geothermal one. Would a standard air heat pump work, and what are the newest designs?

A: Heat pumps are becoming a more common alternative to central air conditioners because they can also heat your house. The cost of electricity for heating and cooling a house is less volatile than natural gas, oil or propane. You may also get up to a $1,500 tax credit for installing a heat pump.

A geothermal heat pump is one of the most energy-efficient heating and cooling systems for any climate. Even though it provides a good payback on the investment, the initial installation costs are considerably higher than for air-source models.

An air-source heat pump is basically a central air conditioner with extra parts. During the summer, it draws heat from the indoor air and, through a refrigeration cycle identical to an air conditioner, expels the heat outdoors. The cooling efficiency is rated by its SEER (seasonal energy efficiency ratio).

During the winter, a reversing valve inside the outdoor condenser unit switches position. This reverses the flow of the refrigerant so it begins to draw heat from the outdoor air and transfers it to an indoor coil. Heating efficiency is rated by HSPF (heating seasonal performance factor).

There have been many recent developments in air-source heat pumps. The modulating, multistage output rotary compressor design is now available in heat pumps. This design produces high efficiencies for both heating and cooling (HSPF of 10 and SEER of 22). What this means is you can get $2 to $3 worth of heat for each $1 on your utility bills.

This heat pump uses a rotary compressor with inverter technology to vary its heating or cooling output from about one-third to full capacity output. This saves electricity and produces extremely good comfort, quiet operation and even room temperatures. Two-stage heat pumps also improve efficiency and comfort over standard single-stage models.

Another two-stage heat pump design couples a solar panel with the outdoor unit. On a sunny day, this solar panel produces enough electricity to operate the condenser fan for up to an 8 percent electricity savings.

Update Bulletin No. 312, available by mail or at dulley.com, is a buyer's guide to heat pumps, listing stages, efficiency, compressors, blower speeds and a savings/payback chart. Please include $3 and a business-sized, self-addressed, stamped envelope.

Send inquiries to James Dulley, St. Petersburg Times, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.