Emergency Heat

Updated: 02/01/2021

When Should I Use the Emergency Heat at My House?

When your home’s heat pump fails, you don’t have to find your matchsticks and build a bonfire. Heat pumps rely on their emergency heat source to keep the indoors warm. But when should you activate it?

What is the Emergency Heat?

The emergency heat is a supplemental heat source for your home. In regions where temperatures can drop below zero degrees, heat pumps require “back-up” heating to keep your home warm in case the heat pumps stop working. Emergency heat is referred to as “second-stage” heating, while the heat pumps are your “first-stage” heating source.

When Should I Use the Emergency Heat?

As the name states, you should only activate the emergency heat setting during emergencies. When your heat pump malfunctions, you’ll need a secondary source to provide warmth, or else you risk freezing under sub-zero temperatures. The moment you notice that your house is getting colder and colder, even though you turned on the heat pump, switch to emergency heat. It would then be ideal to call a heating and cooling technician to fix your heat pump.

Aside from acting as a backup heating source, the emergency heat assists your main heating source in maintaining the desired temperature. In some modern heat pumps, the emergency heat automatically turns on once it detects that the outside temperature is lower than 30°F. It’s also common for the emergency heat to automatically turn on if you bump up your thermostat by 2 degrees since your heat pump was designed to reach the preferred temperature as quickly as possible.

For example, if the outside temperature is 16°F, and you set your thermostat to 75°F, your heat pump may not be strong enough to warm the home. Your heat pump will then automatically engage the emergency heat.

Is Running the Emergency Heat Expensive?

If you use an entirely electric heat pump, then the answer is yes. This is because greater energy is required to activate the emergency heat coil. It is estimated that nearly $200 is spent each week on using the emergency heat. This is why you should avoid using your emergency heat unless it’s an emergency.

If your backup heating system relies on gas or oil, the increase in your electrical bill won’t be as massive. However, it still depends on other factors including the cost of fuel, the efficiency of your heat pump, and so on.

How Can I Turn on the Emergency Heat?

Your thermostat should be equipped with an emergency heat setting. This is usually labeled as “E” for “Emergency”. To engage it, manually switch to the setting -- a red indicator light should signal that it has been activated. This light will stay illuminated until you stop using the emergency heat. However, if the thermostat flashes red, this may indicate a problem with your first-stage heating source.

Bottom Line

If you’re concerned about your emergency heat source, or you want to replace your current one with something more cost-efficient, it pays to call your local technician. If you have a wellmaintained heat pump, it’s unlikely that you’ll have to use your emergency heat anytime soon. Still, it’s a good idea to have your heating systems regularly checked so that you won’t experience cold nights