Emergency Heat: Everything You Need to Know

What is emergency heat?

Emergency Heat, also known as “auxiliary heat”, is the second stage of heat that your thermostat runs on when the temperature is too cold for your heat pump to extract heat from the outside. Emergency Heat is typically triggered when it is 35°F and below outside.

Since this second stage heat source is designed to be just that, secondary, running your heat pump on emergency heat increases your HVAC system’s energy usage and results in escalating energy bills.

Heat pump emergency heat

How does emergency heat work?

In most cases, a emergency heat’s source is electric, but it can also run on natural gas or oil. Think of an electric second stage heat source like a strip of heated coils in a toaster within your air handler. If your second stage heat source is oil or gas, it’s probably hooked into your furnace.

When you set your thermostat to emergency heat, your system bypasses the heat pump and directly accesses either the electric heat strip or gas/oil furnace heat. For electric systems, this turns your air handler into an electric furnace, which can be costly to run for extended periods of time.

When should I turn on emergency heat?

Many people assume that emergency heat is designed to be turned on by the homeowner during especially cold weather, but that’s not quite right. Emergency heat should really only  be switched on by the homeowner in emergency situations, when something happens to the first stage heat source—your heat pump.

For example, if a tree limb weighed down by snow falls on your outdoor unit and damages it, you should switch on your emergency heat and call an HVAC professional. If your heat pump is malfunctioning and shorts out or freezes over, flip the switch and call for an HVAC maintenance appointment.

For all-electric systems, your emergency heat system should keep you warm until your heat pump can be fixed. For gas or oil furnace second stage systems, you should be fine for longer periods of time.

The point is, the emergency heat setting is meant to temporarily keep your home warm while you get your heat pump repaired. It’s not meant to run indefinitely.


How to use emergency heat correctly

Now that you know what emergency heat is for, make sure you’re using it right. Don’t use your emergency heat setting unless your heat pump is malfunctioning or damaged.  Save yourself money by keeping your thermostat setting on “Heat” during the winter. If you do need to switch to emergency heat, contact an HVAC professional as soon as possible to get your heat pump working again. If you continue to use emergency heat, you will run up a massive energy bill.

Learn more about heat pumps and other types of heating systems today. Check out our complete guide to heating for more information.

Emergency heat FAQs

How do you turn off emergency heat?

Turning off emergency heat is not recommended. If you turn it off, your heating system won’t work once outdoor temperatures drop below a certain temperature, usually 30 degrees Fahrenheit. You would need to cut power to the whole system and use a different heating source, like a wood stove or pellet stove.

Why did my emergency heat setting kick on?

Your emergency heat setting automatically turns on when outside temperatures drop below a certain temperature, usually 30 degrees Fahrenheit. If you need to manually turn it on, you should call an HVAC professional to get your heat pump fixed.