Heat pumps are among the most efficient methods for home heating and cooling since they don’t require an expensive fuel source to provide heat. Instead, they utilize pressurized coolant to absorb ambient heat from the outside air.
This heat energy can then be transferred to the inside of a home with minimal energy costs. The fact that they don’t need to generate heat is the major selling point of heat pumps, but it can also lead to a major downside: what happens if it’s simply too cold outside for them to operate effectively?
There’s also the possibility of equipment failure or damage to consider. For this reason, it’s a good idea to have some sort of emergency backup method for heating the home. But do all heat pumps have emergency heat? How does emergency heating work? What activates it, and can it be turned on and off manually? Read on for the answers.
Most heat pumps are constructed from a two-part system, with an indoor unit and an outdoor unit. The outdoor element contains refrigerant coils; these coils contain a cold, low-pressure gas known as a coolant. Because it’s cold, heat energy can easily move into the coolant gas thanks to the second law of thermodynamics.
This means that when your heat pump draws in air, the coolant gas will draw the heat energy out of it, expanding as it does so and becoming very hot. The coolant is then pumped into the indoor unit, where it heats the indoor air and vents it into the building until the desired temperature is achieved.
Your heat pump is very good at drawing ambient heat energy from the outside air. However, if it’s particularly cold outside—as in, below freezing—then your heat pump will struggle to find enough energy to effectively heat your home. On particularly cold days, moisture buildup on the refrigerant coils can cause the unit to freeze over entirely, rendering it nonfunctional until it can be thawed.
Your heat pump may also be damaged during inclement weather. Rain, hail, and snow can do a number on the outdoor unit of your heat pump. While proper installation in a safe area can mostly prevent this from occurring, there is no way to completely avoid the risk of damage to your heat pump, especially when a storm is raging outside. Of course, it’s on these cold and stormy days that you will be likely to need your indoor heating the most.
The fact that there may be days when your heat pump is less effective means that many heat pumps are connected to an emergency backup heat source. This may be referred to as EM heat or sometimes as auxiliary heat, or AUX mode for short.
In most cases, the emergency heat setting in your heat pump will switch on automatically when the thermostat senses that the indoor temperature has dropped too low and the heat pump is struggling to keep up. When this happens, your heat pump will begin using resistance heatingto generate heat with electricity. This can allow the home to remain warm without interruption, regardless of how cold it is outside.
EM heating is capable of running indefinitely, but it will only switch on when it’s needed. On cold days when it’s simply being used to supplement the regular functioning of the heat pump, it may not run much. However, if the heat pump itself has been damaged or otherwise failed in some way, the EM setting may begin to run constantly. This can lead to vastly increased energy costs, so it’s a good idea to have a heating professional come to repair your heat pump as quickly as possible.
Emergency heating is an important feature in heat pumps for homeowners who live in climates where the temperature can drop to below freezing. However, the fact remains that most people who have heat pumps installed are extremely conscious about their energy usage. The major selling point for heat pumps, after all, is the fact that they use very little energy and cost much less to run than most other heating methods.
Once the emergency heating switches on, however, this is no longer the case. The auxiliary heat source is usually electric resistance heating, which is one of the least efficient and most expensive methods of generating heat, meaning that your heat bill can be quite high on the coldest days of the year.
While your heat pump will only use the emergency heating when it’s needed, and not any longer, not everyone agrees on the definition of an “emergency,” and the fact is that some homeowners would prefer to be cold than spend more money on heating than they have to.
For those people, the EM heat can be controlled manually, usually through a setting on your thermostat. It can be switched on or off this way, depending upon the need.
So, do all heat pumps have emergency heat? The answer is no, they do not, and while homeowners living in more temperate climates may be fine without having a backup heat source, for people living in areas where the temperature regularly drops below freezing, EM heat may be critical.
If you are unsure of whether your heat pump has an emergency setting, you should be able to check your thermostat to find out. Otherwise, you can also research the model of the heat pump that you have installed in your home.
If you find that your heat pump doesn’t have an emergency setting, and you would prefer to have one that does, you can source a new heat pump from a company like Entek HVAC. Businesses like Entek have multiple heating options you can choose from so that you can be sure that you will have one that suits the climate in which you live.