By James Dulley, Published October 30 2009
Heat pumps gaining popularity in homesDear Jim: I hear people install a heat pump instead of a furnace and air conditioner even in cold climates. I can’t afford a geothermal one. Would a standard air heat pump work well, and what are newest designs? – Mike H.
Dear Mike: 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, although it gradually increases, as do most prices over time, is much 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, particularly in very hot or cold climates, the initial installation costs are considerably higher than for air-source models.
An air-source heat pump is basically a central air conditioner with a few 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 so 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 extremely high efficiencies for both heating and cooling (HSPF-10, SEER-22). 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 allow it to vary its heating or cooling output from about one-third to full capacity output. This not only saves electricity, but it also 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 new heat pump design is for cold climates. It uses a second booster compressor to allow it to continue to produce heat efficiently at lower outdoor temperatures. It offers four heating and two cooling stages. Other non-booster heat pumps can be coupled with a high-efficiency gas furnace for a hybrid system in cold climates for efficiency and better comfort.
Another new 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.
Write for (or instantly download at www.dulley.com) Update Bulletin No. 312-2009 buyer’s guide of the most efficient heat pumps listing stages, efficiency, compressors, blower speeds and a savings/
payback chart. Please include $3 and a business-size SASE.
Dear Jim: I am remodeling my family room, and adding some new wiring. I have the specifications for the size of wire to use. If I use larger wire, will it have less resistance and waste less energy in the walls? – Jan F.
Dear Jan: It sounds as though you understand Ohm’s Law. A larger diameter (lower gauge number) electrical wire has less resistance and wastes less electricity. The actual savings though is negligible. More electricity is probably used manufacturing the larger copper wire than you would ever save.
The best advice is to always follow electrical codes as to the size of the wire required for the maximum amperes on a specific circuit.
Send inquiries to James Dulley, The Forum of Fargo-Moorhead, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com