Emergency heat is a setting on a thermostat that controls a homes backup heating system. It is typically used in conjunction with a heat pump, as well as a gas, oil, electric, or hot-water backup system. When the weather gets too cold, the heat pump may not be able to pull enough warmth from the outdoor air to heat the home to the desired temperature. In this case, a secondary heating source, like emergency heat, can be used to keep the home warm.

Emergency heat can be activated automatically by the thermostat when the primary heating system is unable to handle controlling the temperature on its own or there is a problem with the heating system. It can also be turned on manually by the homeowner, but this should only be done in the case of a heating emergency, such as when the heat pump is broken.

When emergency heat is activated, the system bypasses the heat pump and directly accesses either the electric heat strip or the gas or oil furnace. This puts a great strain on the backup element that is only meant to be used in extreme circumstances for short periods of time. Therefore, it is important to use emergency heat only when necessary and to turn it off once the primary heating system has been fixed or the temperature has risen.

In summary, emergency heat is a backup heating system that is used when the primary heating system is unable to handle controlling the temperature on its own or there is a problem with the heating system. It should only be used in a heating emergency and turned off once the primary heating system has been fixed or the temperature has risen.