what is emergency heat on thermostat

What Is Emergency Heat on a Thermostat and How Does It Work?

With the colder weather setting in and winter fast approaching, more people are looking into servicing their furnaces and heaters in order to ensure that their homes and businesses remain warm and comfortable.

One issue can often pop up, though. Emergency heat is one of the few settings not used all that often, depending on where your home is located. Considering how rare its needed use can be, you may be questioning, ‘What is emergency heat on a thermostat?’.

If you’re interested in learning more or need to call someone to check out your HVAC equipment for repair or maintenance, call Smart Air for help.

What is emergency heat on a thermostat?

When it comes to heating your home during the winter months, the amount of warm air you get can depend on your living situation. Since the outside air is often quite cold the further up north your home is, it’s unlikely that there will be enough warmth outside to provide proper indoor heating. 

This is where the emergency heat setting on a thermostat comes in. Many heat pumps with an emergency heat setting have a backup heater to provide the remaining heat needed to warm an indoor space. This secondary heater uses any kind of power source, whether it’s gas or electric.

Once a thermostat receives a reading that a heat pump is overworked and needs to stop momentarily to avoid system damage, the secondary heater and emergency heat (or “em heat”) setting are turned on.

How does emergency heat work?

As mentioned, emergency heat only kicks into drive when the primary system is unable to draw in the heat needed to warm the home. Typically, this means that both the heat pump and the compressor turn off while the system’s heat strips turn on.

While this is usually done automatically, some thermostats allow the function of turning on the emergency heat setting manually. Regardless, the emergency heat settings on your thermostat should create more heat in case your main pump can’t create more or needs to turn off to prevent overheating.

When should you switch from heat pump to emergency heat?

As the name suggests, emergency heat will also kick in automatically during an emergency situation, such as a heat pump freezing or breaking down. When it comes to when to use emergency heat on a heat pump, situations like malfunctions or short-outs are the best times to ensure your home remains warm while waiting for repairs or for the issue to resolve itself.

While the setting is incredibly useful, it should only be used in these kinds of emergency situations. Emergency heat settings, after all, can damage the secondary unit in long instances and if used for a much longer time than needed. It can be quite taxing on the backup and should always be turned back off (or will shut off automatically) once repairs are made or the heat pump thaws out.


The answer to ‘What is emergency heat on a thermostat?’ is quite simple. While you may not always need to use the emergency heat setting, it helps to know that it’s there. 

Many heat pump models today are made specifically to heat homes under certain conditions, so it’s safe to say that the emergency heat setting is a useful function.