Efficiency of heat pump
Heat pumps are potentially the most efficient type of electric heat. When heat pumps properly installed, heat pumps can deliver 1 1/2 to 3 times more heat energy to a home than the electric energy they consume. Unfortunately, the energy savings produced by the heat pump’s design are often lost to poor installation and neglected maintenance.
All heat pumps include two different heating systems: compressor heating and auxiliary heating. During moderately cool weather, your heat pump engages it’s first stage to heat your home. In this most-efficient mode, it works like an air conditioner in reverse, using a compressor to circulate refrigerant through the outdoor coil and gathering heat from the outdoor air. The refrigerant then carries heat to the indoor coil and releases it into the home. This first stage works well down to about 35 degrees. Below this temperature, heat pumps don’t work as effectively, and the second stage of heat is activated. This less-effective stage utilizes electric resistance coils to produce heat, but it is the only option during severe weather. Heat pump thermostats usually have a light that alerts you when resistance heat is on. The more your system depends on the resistance coils for heating, the higher your energy bill. Efficiency improvements can reduce your reliance on this second-stage electric resistance heat.
Duct leakage is the most serious and common cause of high heat pump energy bills. Duct leaks allow your expensive conditioned air to leak to the outdoors. The most important duct air leaks are those nearest the heat pump’s indoor cabinet because the air pressure is greatest there and the temperature of the air is the highest. Sealing these duct leaks can save you a lot of energy and money.
Incorrect refrigerant charge is another common performance problem. An incorrectly-charged system must work overtime to deliver heat to the home. A qualified technician can check this charge and add or remove refrigerant as needed. Inadequate airflow also lowers the performance of heat pumps, and under-sized ducts are the most common cause. Proper duct sizing solves this problem.
Though many heating and air conditioning companies don’t include testing and adjustment of refrigerant and airflow during their service calls, you should ask to have these important procedures included. Your technician should test and seal duct leaks, check and adjust refrigerant charge, and test and improve airflow. All are worth the expense to be sure that your heat pump is operating at maximum efficiency.