Should You Be Concerned When Your Heat Pump Runs in Auxiliary Mode?

November 20, 2022
Heat pumps in Olathe, KS

With prices rising on everything in Olathe, it makes sense to save money however you can. One way that many homeowners are able to save some money is by lowering their utility costs with a heat pump. While it’s true that a heat pump is an economical way to heat your home, it does have some unique operational modes that may catch you off guard if you’re not well-educated on the operation of the system. One such mode is called “auxiliary mode.” If you’ve ever seen your system operating in this mode and wondered what it means, the pros at Mike Bryant Heating & Cooling are here to solve this mystery.

How Does a Heat Pump Work?

Essentially, a heat pump is an air conditioner that can work in reverse. An air conditioner works by changing the temperature of a refrigerant in a closed loop by changing the pressure of the refrigerant. After changing the temperature, the refrigerant is able to draw in heat from inside your home and release the heat into the hot outside air. A heat pump performs this process in reverse so that it can absorb heat energy from the outside air and release it into the cooler air inside. Because a heat pump can lower the temperature of the refrigerant to very low temperatures, a heat pump is exceptionally effective at absorbing heat energy, even from cold outside air.

Heat Energy Needed

As effective as heat pumps can be at absorbing heat energy, they sometimes need some help. If the outside air temperature is too cold, the refrigerant will have to get so cold that ice will begin to form on the refrigerant line. Unfortunately, this makes the process of absorbing heat nearly impossible. To remove the ice, a heat pump will go through a defrost cycle. This is when the system reverses the points at which the refrigerant is under low and high pressures. Thus, the refrigerant can absorb heat energy from inside your home. However, rather than expelling the heat outside, the system uses the heat energy in the refrigerant to melt the ice on the refrigerant line until the line is completely defrosted.

Enter Auxiliary Mode

At Mike Bryant Heating & Cooling, we know that you’ve likely figured out by this point that if your heat pump reverses the flow of heat energy, you’ll be getting cold air inside your home. That’s where auxiliary mode comes in. When a heat pump operates in auxiliary mode, it turns on a secondary heating element, usually powered by electricity. This heating strip will heat the cool air as it flows through the heat pump, allowing you to have an uninterrupted supply of warm air while your system defrosts. Your thermostat will display “Aux,” “Auxiliary,” or some other similar message to let you know that your system is using its backup heater. The length of time that a heat pump uses its auxiliary mode is largely dependent on the outside temperature.

Downsides of Auxiliary Mode

There’s one major drawback to auxiliary mode: It makes your system much less efficient while it’s operating. During normal operation, a heat pump is only using electricity to move heat energy from one location to another. In auxiliary mode, however, your heat pump is turning electrical energy into heat energy, which is a much less efficient process. The flip side, of course, is that your heat pump couldn’t operate without the defrost cycles that the auxiliary mode allows, meaning that auxiliary mode is basically a necessary evil with current HVAC technology. The good news, though, is that a heat pump running mostly in normal mode is still much more efficient than a typical furnace.

Your Heat Pump Pros

At Mike Bryant Heating & Cooling, we want our customers to be able to stay comfortable all winter long without spending a fortune on energy. That’s why we offer heat pump installation, repair, and maintenance. We also offer furnace repair, air conditioner replacement, humidifier installation, boiler maintenance, and much more. For over 15 years, people throughout the region have been trusting us to take care of home comfort needs, both big and small, and we work hard to earn that trust every day. That’s one reason why we consistently receive five-star customer reviews and maintain a distinction as a Lennox Circle of Excellence dealer. To learn more about heat pumps and how they work, contact us at Mike Bryant Heating & Cooling today.

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