Emergency Heat Mode All You Need To Know

Emergency Heat Mode: All You Need To Know

Homeowners who live in places that hit negative double digits for a good chunk of the year learn to appreciate the little things like heat. Thankfully, there are several ways to ensure that your home is a cozy cocoon when it needs to be. Nowadays, home heating systems provide various methods and functions to keep your comfort. One such feature is emergency heat mode, also known as secondary heat or backup heat. A backup heating system is there to save the day if your primary system fails.

This blog post will explore everything you need to know about emergency heat mode and how it can benefit your home heating system if you live in an area prone to extreme climates and unexpected snow storms.

What is Emergency Heat?

We typically use the emergency heat setting on a heat pump system when the main heating system fails. The emergency heat setting is usually used as a last resort to prevent the home from becoming too cold. When the main heating system fails, the emergency heat setting will turn on the heating system’s backup heating source. Electric resistance heating is the most common type of heat provided outdoors, using the building structure as a conduit. 

An air handler (indoor unit) pumps refrigerant back and forth from an outdoor unit (compressor) to create a comfortable home temperature. Heat pumps move heat from one location to another by using electricity and refrigerant. A heat pump works by pulling in heat from the outside in normal mode. During brief periods when the outside air becomes excessively cold, the emergency heat function on a heat pump will typically switch on and off automatically.

When the ambient temperature falls below 35° Fahrenheit, a heat pumps secondary heating system (gas, oil, or electricity) kicks in to provide supplemental heating. If you activate an electric hot water EM heat pump manually, it will only draw heat from the secondary source, not the primary source. Due to this, your backup heating device will run on its own rather than operating in conjunction with your primary heating system. Even if your primary heat pump is frozen and will not defrost, your emergency heat can be activated while you wait for a professional service technician to examine it.

It is less efficient than your main heating system, so use it only in challenging situations if you want to pay excessive heating costs.

How Does Emergency Heat Work?

Most heating systems have a switch that activates emergency heat when the regular heating system is not working correctly. The thermostat usually has an emergency heat switch near it.

The primary component of a heat pump is the outdoor unit, which collects heat from the air and transfers it to the indoor unit. The second phase of the heating system is inside the house. The second phase provides supplementary heat when the temperature is freezing for the primary heat pump to pull heat from the outdoors. When the temperature falls below the set threshold, the heat pump defrosts and triggers the secondary heat source. 

As a result, you do not need to activate the EM heat setting on your thermostats. Your thermostats will signal when the setting is activated, usually with a light. Emergency heat is not as efficient as the regular heating system, and it will usually result in higher heating bills. However, it is an effective way to keep the home warm until you can repair the regular heating system.

When Should I Use Emergency Heat?

You should use emergency heat when there are emergency situations like the temperature outside is below freezing and your regular heating system is not working. If your gas furnace goes out, your heat pump is not working, or you are without power, you will need to use emergency heat to keep your home warm.

Some individuals erroneously believe that the setting is for freezing days, resulting in higher heating costs (and not much warmth). As discussed, your heating system will automatically activate your backup heating system when the weather gets too cold.

If you have an older heat pump, it may not have an emergency heat setting. In that case, you’ll need to use a backup heating system, such as a furnace, to keep your home warm.

Why Should You Never Use Emergency Heat Unless you Have To?

Emergency heat is typically used as a last resort when your furnace is not working, and you need to generate heat to keep your home warm. While it may seem like a good idea to use emergency heat to keep your home warm, there are several reasons why you should never use emergency heat unless you have to.

First, emergency heat is much less efficient than your furnace, so it will likely cost you more money in the long run. Additionally, emergency heat can be very dry to the air in your home, which can be a problem if you have allergies or asthma. Finally, using emergency heat for an extended period can put a lot of wear and tear on your HVAC system, leading to expensive repairs down the road.

So, while emergency heat may seem like a good option when your furnace is not working, there are several reasons why you should avoid using it unless necessary. If you need to use emergency heat, be sure to monitor the temperature closely and take steps to keep the air in your home moist to avoid any potential health problems.

Switching your Thermostat to Emergency Heat can Lead To

Whether or not you should switch your thermostat to emergency heat mode during cold weather is a decision that only you can make. It’s always good practice to check with a trusted source before changing your thermostat settings. However, if you choose to move forward with this strategy, it’s essential to understand what switching your thermostat might mean for safety and efficiency.

High Energy Bills

Heat can make a difference to keeping your home warm during the winter months. However, it can also cause higher energy bills if you’re not careful. Heat loss is one of the biggest culprits of increased energy bills. One way to help keep your heat bill low is to ensure your home is adequately insulated. Another option is to install a programmable thermostat, which allows you to set different temperature settings for other times of the day.

Another option is to install radiant floor heating, which uses heated floor tiles or heat strips to provide instant warmth even if your central heating isn’t running. It’s also essential to ensure that any vents in your home are clear of clutter and not blocking airflow from the heat strip.

Taxing the System

When you turn on the emergency heat, the system bypasses the heat pump and operates as if the main heat source is not functioning. Because it is only intended for emergencies and short durations, turning on emergency heat forces the system to work at higher temperatures. If you cannot control the temperature or your heating system is broken, your heating system will activate emergency heat. If the fan does not work, set the thermostat to prevent the system from staying on. 

In emergency heating without air movement, you may damage your outdoor unit. Never activate emergency heat manually unless your heat pump has completely broken down. You should get a heating system checkup and repair as soon as possible if your heat pump has broken down. If you need to turn on the emergency heat, please contact Wentzel’s and let us handle the issue.


In the end, it’s essential to make sure that your emergency heat mode is as lightweight, simple, and stealthy as possible. Naturally, conserving power should be a top priority, but keeping heat production at a minimum. Anything to help you save battery life and keep cool until help arrives is in your best interest. Only use this feature if your air conditioning system needs repair or maintenance.


Will emergency heat keep the house warm?

In general, yes. Most homes have a backup heat source, typically an electric heater, which will activate if the primary heating system fails. The emergency heat will not be as strong as the primary heat, but it will typically be enough to keep the house warm until you repair the primary heating system.

Can I use emergency heat all winter?

If your home has a heat pump, you may be wondering if it’s okay to use emergency heat all winter. The answer is that it’s not a good idea, for several reasons. First, using emergency heat all winter will significantly increase your energy bills. Second, it’s not suitable for your heat pump, as it will shorten its lifespan. Third, you may not be comfortable, as emergency heat is less efficient than the regular heating mode. Finally, using emergency heat all winter can be a fire hazard.

Does emergency heat run constantly?

The emergency heat setting on a thermostat is typically used as a last resort when the heat pump is not working properly. The emergency heat setting will run the heating coils in the air handler constantly, which can be costly and may not be necessary if the problem is fixed quickly.