Our recent spate of cold weather has generated a lot of discussion about whether to use the e-heat setting (also called emergency or auxiliary heat) on your heat pump thermostat. PUD energy experts say that a properly designed and installed heat pump can operate continuously in cold weather, and that e-heat should only be used in a real emergency -- like when a tree falls on your heat pump!
Energy consultant Greg Jourdan (at left in photo) agrees. Jourdan, a professor of Environmental Systems and Refrigeration Technology at Wenatchee Valley College, said there is no one point where it's necessary to switch to emergency heat, even if your heat pump is running constantly due to cold weather.
The heat pump has a balance point, Jourdan noted, where it may not be able to extract enough heat from the outside air during cold spells. This is typically around 20 degrees F. When the temperature outside gets below the designed balance point and the temperature in the home starts to drop, the second stage of auxiliary heat (your furnace heat) will automatically be energized to supplement the heat pump to maintain the set point at the thermostat within the home. It will automatically control and compensate during cold conditions to keep your home comfortable.
"The e-heat function should be used only if the compressor is broken or the unit is out of refrigerant," he said. In that case, call a professional for repairs.