Most heat pumps come with some form of emergency heat source, also known as EM heat. Discover why your heat pump has emergency heat, the kinds available, when to use it, and how to avoid needing it.

Understanding How Heat Pumps Work

Before delving into the how’s and why’s of emergency heat, it’s important to understand how your heat pump works. Rather than creating heat through an electric element or by burning fuel, a heat pump transfers heat in the same way an AC does but in reverse.

The most common heat pump is the air-sourced model, which draws heat from the air outside. Even with cool temperatures, there’s enough heat to keep your house comfortable.

However, when the temperature drops into the frigid range, your heat pump may not work as effectively. This happens because the system’s ability to absorb heat is dependent on the temperature difference between the air outside and the unit’s outside coil. The closer these temperatures are, the less heat the system can absorb. Further, if the system has to work hard enough, it may make the coils cold enough to freeze, preventing it from functioning at all.

When your system experiences problems maintaining your home’s temperature, you need a backup plan to keep your family safe. The emergency heat mode is for exactly these kinds of situations, preventing your house from getting dangerously cold.

What Emergency Heating Does

Your heat pump’s emergency heating mode first shuts down the compressor and the rest of the heat pump. It starts a backup heating source, which acts much like a traditional furnace, creating heat rather than transferring it.

The idea is that the emergency heat is used for emergencies where your heat pump is no longer effective. In many cases, this is because of some issue with your unit that may require repair. While you’re waiting for those repairs, you can use the backup heating system to prevent your home from getting too cold.

Keep in mind that relying on the emergency heat will kill the efficiency that’s the driving motivation behind most heat pumps. Use it when it’s needed, but don’t plan to rely on it through the entire winter.

Different Types of Emergency Heat

Heat pumps come with a couple of options for the backup heat that’s used in the emergency heat mode. The standard emergency heating some heat pumps come with is a form of electric resistance heating. This is called a heat strip or may also be called a heating element. Regardless of the name, it’s made of electric resistance alloys that glow red hot when current passes through it. These are installed in the air handling part of your heat pump, so it will easily warm the air passing through the system.

The other option is a fuel-burning heater, usually running on natural gas that’s delivered to your residence through municipal infrastructure. This kind of system is just like a traditional furnace, complete with a heat exchanger to warm the circulating air. Systems with some kind of fuel-burning backup heat are called dual-fuel systems.

Difference Between Emergency and Auxiliary Heat

As you explore the details of heat pumps, you may find both references to emergency heating and auxiliary heating. On the surface, these two are the same, using the same backup heating source we just discussed. The difference is how and when they cycle on.

Auxiliary heating is an automatic feature of heat pumps when the temperature drops below what can effectively heat your home. The auxiliary heating kicks in to bring your system up to your desired temperature without completely turning off the heat pump.

On the other hand, emergency heating is something you have to manually initiate, which also means you have to manually turn it off. As previously mentioned, it turns off the heart pump function of your unit while it’s on. Unfortunately, it’s easy to forget to turn it off, leaving the efficient heat pump turned off.

Is Emergency Heat More Expensive?

The cost of running your emergency heat versus your heat pump comes down to evaluating several variables, including the kind of emergency heat you have and the temperature outside.

As stated previously, the colder the air is outside, the less efficiently a heat pump heats your home. Fortunately, the temperatures around Troutdale are generally mild, making them ideally suited for running a heat pump.

That means that under normal circumstances, running your emergency heating will likely cost more than running the heat pump. However, when the temperature is in the 30s at night and you have a problem with your heat pump, you’ll be thankful for the emergency heat mode.

Moreover, when unusually cold temperatures arrive, that story changes. At that point, the secondary heating source will become more cost-effective than trying to run your heat pump.

When Should You Use Your Emergency Heat?

The most obvious time you should switch to emergency heat is when you have a heat pump malfunction. The circulating fan must still run for your emergency heat to work, so if that’s where the problem is, then this won’t help. However, if the issue is with the compressor, the refrigerant coil freezing up, a refrigerant leak, or other similar problems, then the emergency heat is the right option.

The other time to turn it on is when the temperature drops drastically and quickly. Your heat pump likely won’t be able to keep up with the sudden drop, so running your emergency heat is a good option. Furthermore, when the temperature drops below freezing, you may want to turn to the emergency heat to prevent excessive strain on the heat pump.

Just remember that once you turn on the EM heat, it won’t turn off until you do so manually. Set an alarm or some sort of reminder to turn it back off once you don’t need it any longer. The right time to turn it off is once the outside temperature comes back up to an optimal operating temperature or once you’ve completed the needed repairs. In the case of repairs, your technician may remind you to turn off the emergency heat mode, or they may even turn it off for you.

How to Avoid Needing Your Emergency Heat

As much as it may benefit your life, you can’t control the weather outside, including the temperature. However, you can avoid most of the mechanical failures that would require the use of our emergency heating.

The best way to avoid these breakdowns is to get routine heat pump maintenance. During a maintenance visit, your technician will test the system and look for indications of parts working sub-optimally. If they find something, you can schedule the repair before it results in an emergency failure. They’ll also clean the system, which reduces the operational strain. This, in turn, will reduce the number and frequency of mechanical failures.

Apollo Plumbing, Heating & Air Conditioning has been the trusted name in residential comfort and safety around Troutdale since 1984. Our expert team provides heating and air conditioning installation, repair, and maintenance, along with a full range of plumbing services like water heaters, leak detection, and drain inspection and repair services. Call to schedule your heat pump consultation with one of our trusted HVAC technicians today.

Meet the Author
Brandon Bird
Brandon Bird

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