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How to Stop Auxiliary Heat from Coming On – A Winter Guide

When the winter winds start swirling, many people find that their home struggles to maintain a warm and comfortable temperature. Their thermostat is set to help accommodate your preferences, but the temperature may not always remain constant. As the temperature drops two to three degrees below the set temperature, many systems will signal for the auxiliary heat to come on.

What does aux heat mean on a Honeywell system? Short for auxiliary heat, this system is designed to heat your home up quickly instead of waiting for the cold heat pump on the exterior of your home.

Unfortunately, using the auxiliary heat is significantly more expensive than using your heat pump. It may be more effective, but it comes with a specific cost that you might not be anticipating. If your heat pump for the auxiliary heat is always on, expect to see higher electric bills. Many homeowners would prefer to learn how to stop their auxiliary heat from coming on at all.

Learn more about what to do if your aux heat keeps coming on this winter.

My auxiliary heat keeps coming on

First, you should have a good grasp of when it is appropriate for your auxiliary heat to turn on. There are plenty of situations that certainly call for this backup system to spring into action during the winter months. Understanding what is considered normal gives you a better idea of how to correct an issue with your HVAC system on your own.

The auxiliary heat pump should run more often when the temperatures outside dip below freezing. This is because your outdoor heat pump will have a more difficult time creating enough warm air to heat your home. Homeowners who notice their auxiliary heat rise as the temperatures drop may not have a reason for concern.

If the heat pump is in defrost mode, you will also need to make good use of your auxiliary heat.

Another common scenario is when the thermostat calls for a three-degree temperature rise. Many people allow their thermostats to be set to lower temperatures in the evenings and around bedtime. However, they want their furnace to heat their home again quickly in the morning. By bumping your thermostat up three degrees, the auxiliary heat must kick on to catch up with your new demands.

Along these same lines, the auxiliary heat may come on if the unit has been running for ten to fifteen minutes without any change in the temperature of your home. It is signaled as “backup” for your actual heating system since the outdoor heat pump doesn’t seem capable of handling the situation on its own.

When your auxiliary heat runs constantly, and none of these situations apply, it may be time to run some troubleshooting. It is clear that your auxiliary heat may be malfunctioning and could require professional help. On the other hand, it may be something that you can tackle on your own. Here are a few things you might be able to do to stop the heat from raising your monthly heating costs.

How to turn off auxiliary heat on a Honeywell thermostat

It may seem like it isn’t much you can do when your Honeywell thermostat says the auxiliary heat is on. Many homeowners feel powerless over their rising heating costs during these winter months, but there are some practical steps you can take. Learning how to stop auxiliary heat from coming on can actually be quite simple.

Oftentimes, the aux heat is coming on because the temperature in the home is set too high. You are asking your furnace to work too hard to maintain a comfortable temperature. Perhaps you feel most comfortable in the mid-seventies, but the air outside is dipping below freezing. Your outdoor heat pump is unlikely to be able to hold up under these demands. As a result, it will need some assistance from its partner, your auxiliary heating system.

One of the simplest things you can do to keep your Honeywell thermostat from switching to auxiliary heat is to lower the temperature in your home. Setting the thermostat for somewhere between sixty to sixty-eight degrees is all you should need to do to get the problem under control. You may find that this is slightly uncomfortable, but you can make up for it by wearing more layers and snuggling up with a cozy blanket.

Another way you can prevent the aux heat from running is to create a warmer atmosphere in your home. Allow the sun to warm rooms whenever possible. Install the best insulation so that your home can hold heat better. You can run a few extra loads of laundry to take advantage of the heat from the dryer. This is even a great time to turn on your oven for a little holiday baking.

Most people have areas of their homes that are not used throughout the day, so try to keep these spots closed off. Shut the door and close the vents so that the rest of the warm air can be redirected to the rest of your home.

If the temperatures are extremely frigid outside, even this may be too much for your unit. You may need to make some additional changes to your home to keep the auxiliary heat from coming on.

Regular HVAC maintenance

Some people find that their thermostat is stuck on aux heat because their HVAC system simply can’t keep up with a reasonable demand. This is a serious issue that will likely need to be addressed by an experienced technician. You can do your part to keep the auxiliary heat from kicking on by ensuring that the rest of your unit functions at its absolute best.

Before the winter season really begins, it is best to schedule a time to have your system inspected and tuned up. This is a great time to make sure that all of your air filters are changed and that the furnace itself does not need any major repairs.

While this will not shut off your auxiliary heat in a pinch, it may prevent you from having to turn on the auxiliary heat as often. The furnace will be better positioned to keep up with the demands that the thermostat places on it. Instead of allowing the indoor temperature to drop low enough to signal the auxiliary heat, it will be able to keep a more consistent temperature in your main living areas.

If these strategies don’t work, the thermostat could be the issue. Newer thermostats may cause the auxiliary heat to come on more quickly than older ones. If the temperature does not pick up within the first few minutes, many of the new Honeywell models will prompt the aux heat setting.

For those homeowners who never had an issue with their old thermostats but are suddenly experiencing this phenomenon, it may have to do with the specific model of thermostat that you purchased and installed.

When to seek professional help

While you may prefer learning how to stop the auxiliary heat from coming on, there is definitely a time and place for it. Your home needs some of this help from time to time, particularly if you live in a region where the temperatures regularly drop below freezing. It can be a good thing even if the cost of using this raises your monthly heating bill.

However, there is also a time and a place to seek professional help with your thermostat and aux heat.

Pay close attention to when and how often your thermostat reads with the auxiliary setting. Sometimes, you may notice that the aux heat comes on every time the furnace kicks on. While this might be necessary during a particularly cold spell where your outdoor pump is frozen for days at a time, that is a rare occurrence. If the auxiliary heat runs all day long, you need to have your system looked at by a professional.

The issue could lie with your heating system. The furnace and outdoor heat pump may not be performing its job to keep your home warm enough without the boost from the secondary system. Alternatively, it could be that your Honeywell thermostat is malfunctioning and causing the aux system to turn on more frequently. You may need to consider replacing your thermostat.

Either way, these are issues that are best handled by professionals who have the tools to diagnose and correct the problem. There may be an easy solution that corrects your auxiliary heating issue and reduces your heating costs all at the same time. This would be a worthwhile investment that should make up for the service charge fee when opting for professional assistance.

Lifestyle changes to prevent auxiliary heat

For the most part, you can stop the auxiliary heat from coming on by making a few lifestyle changes in your daily routine. Add a few layers to your outfit or sleep with an extra blanket to keep your furnace from working so hard. Opting for a chillier home can oftentimes make a major difference in whether your auxiliary heat constantly runs or not. Other times, it is influenced by the make and model of your thermostat.

While there may not be one clear answer as to how you can prevent the auxiliary heat from coming on, a few of these suggestions may help you to save more money this winter. Try out a few different solutions before contacting a professional. You might be able to save a bundle with a few of these helpful tips and tricks to get your auxiliary heating issue under control.

Michael Joseph


Wednesday 12th of January 2022

"try to keep these spots closed off. Shut the door and close the vents so that the rest of the warm air can be redirected to the rest of your home."

I have read elsewhere that closing doors to unused rooms makes the system work harder. For example, an April 5, 2021 post on states: "It makes sense that if you close off rooms you don’t normally use (or close vents) that the HVAC system in your home wouldn’t have to work so hard and your utility bills would go down. You would think that saving several hundred square feet of home to cool or heat could make a pretty big difference."

"But closing doors actually doesn’t help with energy efficiency. It can actually decrease it and increase your monthly bills. The reason is that closing doors obstruct airflow in your home — and your HVAC unit needs proper air flow to function at its best."

"The air in the room becomes pressurized due to the obstruction. But that pressurized air has to go somewhere and it finds ways to escape. Then, that air is replaced by incoming air: through the chimney, the furnace flue, or even the water heater. This creates a continuous draft in the interior of your home."

This is just one example but I have seen similar advice on other HVAC sites. I was wondering if other readers have received mixed messages about this issue as well.


Friday 8th of January 2021

Hello. I am having an issue with my honeywell 3000 thermostat. It is my understanding that it should not kick into AUX heat unless the temperature setting is set 3 degrees or more above what the temp is reading on the screen. When it reads that the room temp is 70 degrees and I have the thermostat set at 70 degrees why does it kick into AUX heat? Is my thermostat shot? Thanks for any help you can give me. I do not have my switch set to Aux Heat.