New heat pumps cost-efficient
Heat pumps have generally been considered to work well only in warmer climates. Nowadays, however, the right model can warm homes even in cold areas.
The basic operation of a heat pump is fairly simple. Liquid refrigerant within the coils in the outside unit pulls heat from the air, and evaporates into a gas. The coils indoors release that heat as the refrigerant once again becomes a liquid. Even at 15 or 20 degrees F, there is still heat available in the outdoor air. However, when the outside temperatures reaches 40 F, a heat pump struggles. At that point, another heat source, such as an electric or gas furnace, needs to be used for backup.
Choosing a heat pump for a home is like buying any other major appliance: You need to do your homework. Check the heating and cooling performance ratings. While SEER is the rating for air conditioners, the HSPF (heating season performance factor) allows you to compare heat pumps. According to the Department of Energy’s Energy Efficiency and Renewable Energy Web site ( www.eere.energy.gov), efficient models have HSPF ratings of between 8 and 10. Since 2006 there has been a new standard: Heat pumps must have at least a 7.7 HSPF rating.
Here are some considerations for choosing a heat pump:
•While the temperature of furnace-produced air can be as high as 140 F, the air from a heat pump can range from 85 F to 92 F, hot enough to heat a house, but little comfort when you want to stand next to a register to warm up.
•Will the outside unit be protected from wind? Wind can cause the heat pump to experience defrost problems in the coils.
•Attaching a heat pump to existing ductwork can be problematic if the house was not designed for a heat pump or if there are leaky ducts.
•If the amount of refrigerant is not correctly balanced with the airflow through the ductwork, the heat pump won’t be efficient.
Still, the right heat pump can be a cost efficient way of heating your home. Newer heat pump models now come with improved coil and compressor designs, better blowers and split systems with coils both indoors and out. They are one-and-a-half times more efficient than older models.