When Should You Use Emergency Heat?

When the outdoor temperature drops or a heat pump isn’t keeping up, homeowners often start asking when to use emergency heat. That question usually comes up after seeing an unfamiliar “EM” setting on the thermostat or noticing the system isn’t warming the house as expected.

Have you ever wondered what the “EM” mode on your thermostat is? And, have you ever tried to use it? Well, that “EM” on your thermostat denotes Emergency Heat. That’s right! Even your heating system has an emergency option.

However, it might not mean what many of us would expect. Firstly, it’s not designed to be switched on every time you want to increase temperature levels in your house. This means that even though it might be freezing outside, emergency heating might not be the solution. 

Typically, the EM mode is meant to be a backup heating system that keeps your home warm when your primary heat stops working. Mainly, this is when your heat pump fails. 

This guide will help you understand how your heating system works and how you can use the system’s emergency heat appropriately.

What is Emergency Heat?

The emergency heat sign on your thermostat controls the secondary heating system in your home. The EM setting means having a heat pump with hot water, electric, hot water, oil, or gas backup system.

The heat pump is usually the primary setting in many systems and turns on secondary heating when supplemental heat is needed. The heat pumps need second-stage heating in colder areas as it’s unable to draw enough warm air from outside to warm your indoors. This means that when the winter temperatures dip below zero, using your system’s second-stage heating is your best option. 

One thing you should note is that EM mode is not for everyday use. You should only use it for what it is designed for – emergency heating. The system automatically switches on when the weather is freezing but will only go off when you switch it off manually. 

How Does Emergency Heat Setting Work?

The heat pump typically has two heating systems; the primary heat pump and secondary heating. Usually, the secondary source is in the house while the heat pump is outside.

The second stage, heating, supplements the heat pump with heat, especially when it’s too cold for the heat pump to draw heat from outside. Depending on the type of thermostat, it has various ways of activating the secondary source, more so when the temperature is below the standard threshold. 

Also, when it’s too cold outside, the coils on the heat pump become frosty. Subsequently, the system temporarily switches to the secondary heat source to defrost them. The process is automatic, meaning you don’t need to turn on the emergency heat. 

Your thermostat will automatically indicate that the emergency heat mode is running with a light. That way you are aware that you are using your home’s second-stage heating.

Although the secondary source is automatic, you can also switch it on manually. Turning on the “EM heat” on your thermostat instructs your heating system to start using the supplementary source.

When Should You Use the Emergency Heat Mode?

Are you uncertain about when to use emergency heat? It’s simpler than you think. Emergency heating is used only for unexpected eventualities.

You must only turn on the emergency heat when your heat pump stops working or it can’t warm the house. This means that when you notice unusually cold temperatures in your house that are not warming up, you should check the heat pump.

If the heat pump is not producing any heat, you can switch to the emergency heat. Otherwise, your system will automatically switch on your backup heat when the temperature drops too low.

It is important to note that the emergency heat setting is a temporary solution until you fix your heat pump or the coils unfreeze. You can opt for alternative heat sources, e.g., oil or a gas furnace, if a heat pump isn’t enough. While they may take longer to run, they are more efficient and cheaper than emergency heating.

How Does Emergency Heat Work with Your Heat Pump?

Your heat pump generally works by drawing in heat from outside. It will work together with your supplementary heating when the temperature is too low. 

Switching on your emergency heat on the thermostat changes the course of events. The system diverts from the primary heat pump and activates the secondary source. Hence, the system solely relies on the secondary source to produce heat. 

The heat pump stops pulling heat from outside and will only use the electric strip to warm your home. Thus, your heat pump becomes an electric furnace that is expensive to run. Only use the emergency heat when you have to.

And, if you are wondering where the emergency heat comes from, the heat source may be a hot water system, an electric heat strip, gas furnace, or oil. 

Is it Costly to Run Emergency Heat?

Yes!  The emergency heat mode uses more energy compared to the heat pump. Therefore, it’s relatively expensive in the long term, and you should try to avoid it. Once you notice a problem with your heat pump, get it checked as soon as possible.

Here is why you should use emergency heat only during emergencies:

High Electricity bills

Running your electric emergency heat will significantly increase your utility bill. Switching your source of heat from the heat pump is inefficient and costly.

Strains Your System

Forcing your EM system to bypass the heat pump and become the primary heat source taxes your system. It puts so much pressure on the heating system, thus should only be used for a short time.

On a regular mode, your heating system will use emergency heating when there’s a problem with the heat pump. Remember to switch on the fan during emergency heating to allow air movement and prevent damage. Only turn on the emergency heat manually when your heat pump completely fails.

Emergency Heat is a Short-Term Solution

Despite the type of heating system you’re using, the emergency heat on your thermostat offers a temporary solution. You need to turn on the switch only during emergencies. It is costly and puts pressure on your heating system.

Now that you know how the emergency heat works and when to use it, always ensure that your heat pump is functioning well. But if you notice that your heat pump is not heating up, you must immediately contact a technician to come and fix it. 

Installing a gas furnace as an alternative heat source is efficient, and you’ll save more on your utility bills.

Further Reading

• What to Do When AC Compressor Freezes Up
• Most Common HVAC Problems
• What Size of an Air Conditioner Do I Need?