Heat Pumps Provide Energy-Efficient Cooling < Return
An air-source heat pump can provide efficient cooling for your home, especially if you live in a warm climate like ours. When properly installed, a heat pump can deliver one-and-a-half to three times more heat energy than the electrical energy it consumes. This is possible because a heat pump moves heat rather than converting it from a fuel.A heat pump’s refrigeration system consists of a compressor and two coils made of copper tubing (one indoors and one outside), which are surrounded by aluminum fins to aid heat transfer. In the heating mode, liquid refrigerant in the outside coils extracts heat from the air and evaporates into a gas. The indoor coils release heat from the refrigerant as it condenses back into a liquid. A reversing valve, near the compressor, can change the direction of the refrigerant flow for cooling.
The efficiency and performance of today’s air-source heat pumps is one-and-a-half to two times greater than those available 30 years ago. This improvement in efficiency has resulted from technical advances and options such as these:
- Thermostatic expansion valves for more precise control of the refrigerant flow to the indoor coil
- Variable speed blowers, which are more efficient and can compensate for some of the adverse effects of restricted ducts, dirty filters, and dirty coils
- Improved coil design
- Improved electric motor and two-speed compressor designs
- Copper tubing, grooved inside to increase surface area.
Here in Southwest Florida, the average homeowner doesn’t use the heat pump much for heating, but it’s still good to know your heating efficiency. This is indicated by the heating season performance factor (HSPF), which is the total space heating required during the heating season, expressed in Btu, divided by the total electrical energy consumed by the heat pump system during the same season, expressed in watt-hours.
Cooling efficiency is indicated by the seasonal energy efficiency ratio (SEER), which is the total heat removed from the conditioned space during the annual cooling season, expressed in Btu, divided by the total electrical energy consumed by the heat pump during the same season, expressed in watt-hours.
When looking at heat pumps, be sure to check out the Seasonal Energy Efficiency Ratio (SEER). This rates a heat pump’s cooling efficiency. In general, the higher the SEER, the higher the cost. However, the energy savings can return this initial investment several times during the heat pump’s life. Replacing an old central heat pump with a SEER of 6, for example, with a new unit (SEER=12) mean you’ll use half the energy to provide the same amount of cooling. This cuts your air conditioning costs in half. The most efficient heat pumps have SEERs of between 14 and 18.
