what is em heat on thermostat

The "EM heat" setting on a thermostat stands for emergency heat. It is a setting that controls your home's backup heating system, which is used as a secondary heating source when the primary heating system fails. This setting is typically found in homes with a heat pump and a secondary heating system such as gas, oil, electric, or hot water. It is important to note that the emergency heat should only be used in case of a primary heating system failure, and not as a regular heating option, as it can reduce the heating efficiency of the system and increase utility costs