Are dual-fuel heat pumps right for you?

Conventional heat pumps are great at pumping heat in or out of a house in moderate temperature swings. But they're notoriously inefficient and expensive during cold winters. "Dual-fuel" heat pumps are different. Here're some things to consider to see if dual-fuel pumps are right for you.

• Attached to your existing furnace, a dual-fuel system looks (and works, during the summer) like a high-efficiency central air conditioner (A/C).
• However, in those mild spring and fall months, these pumps provide cheap heat.
• As the temperatures drop, the pump shuts off and tells your furnace to take over.
• A dual-fuel heat pump will cost about 20 to 25 percent more (including installation) than an average A/C unit.
• Depending on your region and fuel costs, however, a dual-fuel pump can pay for itself in five or six years.

• Heat pumps save energy because transferring heat is easier than making it.
• Surprisingly, even when it feels cold outside, there is still a decent amount of heat waiting to be pumped.
• Under ideal conditions, a heat pump can transfer 300 percent more energy than it consumes.
• In contrast, a high-efficiency gas furnace is only about 90 percent efficient.

• An air-source heat pump is basically a hybrid air conditioner.
• Both have a compressor (a high-pressure pump) that circulates refrigerant (a volatile gas) through indoor and outdoor coils, a network of tubes designed to facilitate the capture and release of heat.
• While an air conditioner can move refrigerant in only one direction, a heat pump can force refrigerant in either direction, for heating one way and cooling the other.
• The pump does this thanks to an extra diverting device called a switchover valve.

To figure out whether a heat pump is practical for your home, you'll need to contact a heating contractor and get information about these issues:

1. A heating and cooling load analysis

• Don't trust the label on the old furnace; ask your installer to show you the math.
• According to some reports, there's a good chance that your system may not have been sized correctly in the first place.
• Even if it was sized properly originally, subsequent home improvement projects (new insulation, new windows or an addition) can change your heating and cooling needs.

2. Check the numbers

• Manufacturers use different technologies, but one number can provide an apples-to-apples comparison.
• For cooling efficiency, check the unit's Seasonal Energy Efficiency Ratio (SEER).
• The higher the SEER, the more efficient the unit is.
• Of course, units with higher ratios cost more, but every two points can reduce cooling costs by about 15 percent.
• Energy Star-certified pumps are at least eight percent more efficient than standard models.

3. Conduct a comparative cost analysis

• If you live in an area with lower-priced natural gas and sky-high electrical rates, a heat pump will not pay itself off as quickly.
• Your installer can factor in local energy rates (including peak and off-peak electrical rates) to calculate your potential savings and payback.

4. Ask about compatibility

• Dual-fuel heat pumps are designed to work as a straightforward A/C replacement, but older furnaces probably won't work with a new switch-hitting system.
• You'll probably have to upgrade to a brand new furnace to have this system — adding a sizeable chunk to the cost of the project.

5. Check into tax credits

• In addition to saving money in the long run, a dual-fuel heat pump might pay you back right away.
• This upgrade may qualify for an energy-savings tax credit plus rebates.
• Ask your utility company and HVAC (heating, ventilation, and air conditioning) installer about available incentives in your area.

Consider this information if you're thinking about installing dual-fuel heat pumps to help you make an informed decision.