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Question: What is the control inside my heat pump that adjusts from 0 to 45?

Question: I have a 1995 Nordyne heat pump. I have a part that I can not figure out what it does? I noticed beside the defrost control board is a control that can be turned and adjusted from 0 to 45. What does this control do? The knob is missing and I can’t tell what its set on. Thanks, Chris

Answer: Great question! I really do not have a Nordyne parts program, but more than likely the control that you are referring to is probably a auxiliary heat thermostat. Some installers installed these controls to automatically turn on the auxiliary heat (electric, gas) when the set outdoor temperature is achieved. So if you set this control to 30, when the outdoor temperature reaches 30 degrees the auxiliary heat (most of the time electric heat) will come on along with the heat pump so you do not feel cool air coming out of the registers. This saves on your heat pump run time because the heat pump is getting a boost from using the auxiliary heat. If the outside temperature goes above 30 then you only use the heat pump’s heat and not any auxiliary heat. When I was doing installs I would use these thermostats to make sure a customer feels warm when the temperature is real cold outside. I would set the control at 20 degrees. Many installers and apartment complexes recommend turning the emergency heat on when the temperature goes below 30 for long periods of time. With the auxiliary heat thermostat you do not have to worry about turning the heat pump to emergency heat because it senses the need for the emergency heat or aux heat automatically. I hope this answers your question. God bless you and your family. Steve

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