During a Clayton Home Inspection, I test several heating and air conditioning functions. One of those functions is Emergency Heat strips. Heat pumps have an emergency back up heat system that is designed to provide heat in case of heat pump failure (as a side, auxiliary heat strips provide heat during unit defrost and when the heat pump can’t meet demand due to cold outdoor temperatures).
After 2012 (when Energy Code was adopted), some HAVC contractors program systems such that Emergency heat will not turn on when thermostat is set in Emergency heat mode if the outdoor temperature is above 40 degrees.
This is not desirable. According to NC Residential Code, Emergency heat strips can be programmed to turn on even above 40 degrees outdoors. HVAC installers do not have to program the system this way, but I've found that about 95% of them do.
Let’s say you have a heat pump failure (capacitor, transformer, compressor, etc). To obtain heat, you would simply switch the thermostat to Emergency heat, raise the temperature, and heat should be generated. However, some contractors will lock out your Emergency heat if above 40 degrees outside. You would be quite cold in your home without heat! And, for how long? And, does this occur on a Saturday evening at 9 PM, when service calls are extremely expensive?
The confusion is that, per Energy Code requirements, Emergency heat should not turn on when the heat pump compressor can meet the heating demand if above 40 degrees outside. When the heat pump fails, clearly the compressor cannot meet the heating demand.
So, prior to having a new heat pump installed, ask the HVAC contractor if they will program your system such that the Emergency heat will turn on with outdoor temperatures above 40 degrees. Tell them your home inspector gave you this information.
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