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What Does Aux Heat Mean on Your Thermostat
If you’ve ever taken a look at your thermostat and noticed that it says aux heat or just aux, it can be a little bit confusing. Auxiliary heat is typically a part of your normal heating system’s operation. However, there are times when this can signal a problem that needs prompt attention from a professional. Understanding the differences between the two can help you have peace of mind about what steps to take next.
What Does Aux Heat Actually Mean?
Aux heat stands for auxiliary heating. It’s a secondary heating source that your heat pump uses alongside your primary heating system. Heat pumps are specifically designed to operate efficiently when it comes to moving heat from outside into your home. Even in cold weather, it can extract heat from the air and bring it inside.
However, standard heat pumps struggle to extract heat when outdoor temperatures drop too low. Sometimes, your heat pump alone won’t be able to produce adequate heat to keep your home at your desired temperature setting. This is when auxiliary heating comes into play.
Auxiliary heat is typically powered by electrical resistance heating strips. It’s easiest to think of these as similar to a heating element inside your toaster. The electric heating element produces heat that your indoor air handler unit disperses throughout your home to warm it up. This helps provide additional warmth to ensure that your home stays comfortable for you and your family.
Is It More Expensive?
One of the biggest draws for getting a heat pump is its energy efficiency. When your heat pump is operating at temperatures above freezing, its efficiency is typically better than any other heating system on the market. However, when temperatures drop below freezing, it switches over to auxiliary heat.
Auxiliary heating is much more expensive to run because it relies solely on electricity to generate that heat. Your heat pump is no longer extracting heat from the air outside and simply transferring it. Powering your heat pump’s internal heating element consumes much more energy than simply transferring heat from one location to another.
When Should Aux Heat Be Running?
Auxiliary heating is completely normal for several different situations. If the temperature outside is near or below freezing, your heat pump will struggle to extract enough heat from the outside air. It’s normal for it to switch over to auxiliary heating to help maintain a comfortable indoor environment. If you’re only noticing your thermostat has aux heating on during particularly cold days or nights, then you can assume it’s pretty normal.
Another normal situation where auxiliary heating can take over is when your heat pump is going through a defrost cycle. Defrost mode is necessary when your heat pump’s coils develop ice on their surface. To prevent a thick layer of ice buildup, your system will go into defrost mode. This is where it actively heats the outside coils in your condenser unit to remove the thin layer of ice.
It’s also perfectly normal for your heating system to switch to auxiliary heating if you increase your thermostat’s temperature significantly. For example, if your temperature is set to 65 degrees Fahrenheit and you raise it up to 72 degrees, your system may kick over to auxiliary heating so that it can warm up your home quicker.
If you use a programmable thermostat that lowers the temperature overnight, your system may switch over to auxiliary heating in the early morning. This is to bring your home back up to your desired temperature setting. Anytime that your system is using auxiliary heating in any of the situations that we described above, it’s considered perfectly normal.
When Auxiliary Heating May Be a Problem
If your thermostat is displaying auxiliary heating all the time, even when the temperatures outside are mild, it indicates a malfunction with your heat pump. There are several different causes of this problem. Some include low refrigerant levels, a malfunctioning outdoor unit, a damaged reversing valve, and a failing compressor. This happens when your heat pump is solely relying on auxiliary heating instead of its more energy-efficient normal operation.
If you happen to notice a sudden increase in your energy bills and see that your thermostat has auxiliary heating on, it typically means that there’s a malfunction with your unit. It’s overusing your backup heat source due to several different reasons. Some of these include a dirty air filter, an inefficient heat pump, leaky ductwork, and poor insulation in your home.
If you notice that your auxiliary heating seems to be turning on and off frequently, or behaves somewhat unpredictably, it could indicate a control issue with your unit. This might be a faulty thermostat, a control board malfunction, or even a wiring issue. Inconsistent operation can reduce the efficiency of your heat pump and lead to unnecessary wear and tear on your unit.
Reducing Your Reliance on Aux Heating
When your heat pump is running in auxiliary heating mode, it’s consuming much more energy, which leads to higher energy bills for you. Luckily, there are several different things that you can do to help minimize how often your heat pump relies on auxiliary heating. Start by making gradual temperature changes.
Anytime that you make a big change in temperature, it can cause your unit to switch to auxiliary heating to warm your home up fast. Only increasing the temperature by a few degrees at a time can eliminate this unnecessary auxiliary heating instance.
Another must-do is to invest in regular maintenance for your HVAC system. Routine maintenance includes tasks like checking refrigerant levels, inspecting electrical connections, cleaning coils, and changing air filters. A well-maintained HVAC unit is much less likely to rely heavily on auxiliary heating throughout the colder winter months.
Another thing to consider is improving the insulation of your home. If your home has little or no insulation, consider adding some to enhance the efficiency of your heat pump. Aim for sealing up any air leaks around your door or window frames that could be allowing cold air to seep into your home. Insulation and proper weather sealing can help to reduce the workload on your HVAC unit.
When to Call a Professional
Any time that your heat pump is in auxiliary mode when it really shouldn’t be, it’s a cause for concern. Issues like your auxiliary heating running consistently or frequent spikes in your energy bills indicate that you need professional assistance. It’s always best to contact one of our HVAC technicians so that they can diagnose the root cause of the issue and repair it.
You never want to keep using your heat pump if it’s relying solely on auxiliary heating, as doing so could lead to extremely expensive energy bills. It can also lead to excessive strain on your system and shorten its overall lifespan.
Expert AC Repair Service
Black-Haak offers expert AC repair service for Greenville, WI and the surrounding areas. We can also assist with all your AC installation, replacement, and maintenance needs. Contact our office today to schedule an appointment with one of our friendly technicians.
