Should I Set My Furnace Fan To ‘On’ Or ‘Auto’ In The Winter?

Are you wondering whether you should set your furnace fan to ‘on’ or ‘auto’? Are you unsure of what the difference is and which one works best for your home? We can help! For many people, furnace modes are misunderstood and underutilized, which is a shame considering how beneficial they can truly be.

Overall, AUTO is the best setting for your furnace during the winter. This setting is one that allows you to carry on with your everyday life and responsibilities without having to worry or make the time to adjust. The home will automatically heat up when necessary and cool down in the same manner, making it the perfect household companion for the chilly season.

In this article, we’ll cover everything you need to know about these two modes, the nuances between them, and how they affect your heating system. Why Does the Mode on Your Furnace Matter?

Furnace Fan

The mode on your furnace controls whether the fan is running or not. It’s important to understand why this matters, because it has a big effect on both your comfort and energy bill.

The fan circulates warm air throughout your home and helps circulate stale air out of your house so that you can stay comfortable without having to use as much heat. If you have the fan set on auto mode, then it will automatically work when needed.

This means that it may be running more often than necessary if there’s no one in the house or during times when it’s very cold outside (when you want full efficiency from your furnace). On the other hand, if you set your fan to “on” mode all day long because of how cold it is outside be aware this might cause a mess inside!

And what about energy bills? The biggest issue here is draftiness from drafts around windows and doors–a problem that only increases when we’re not using our furnaces nearly enough due to low temperatures outside during winter months.

Even for energy bills, “auto” is the setting that takes the cake for efficiency and “best bang for your buck”. There is no point in cranking heat to the point where everyone is stuffy, and with “auto”, there’s no reason for someone to have to be making constant adjustments to the thermostat when it could be automatic.

Understanding the ‘Auto’ Setting

Let’s start with the “auto” setting.

This mode is the most efficient for your HVAC system and will keep your home at a comfortable temperature throughout the day. When it’s cold outside, the fan will turn on to circulate warm air throughout your home. Then, when it gets warmer, a sensor inside of your furnace will sense this change and stop running so much energy through the system (more on that below).

This mode reduces energy waste and also decreases the amount of time that has to be spent by individuals within the space on regulating temperature and planning around the most fitting times, as well as constantly fussing with the controls- which is not an ideal way to spend time.

Thermostat Fan Mode

Auto settings take the worry out of what the best possible action is for your furnace at any given moment, because it is automatically calculated.

Understanding the ‘On’ Setting

The “on” setting is just what is sounds like—your blower motor will run all day long until you turn it off manually or use another control method. The ‘On’ setting ensures that your furnace fan is constantly running, even when the temperature inside the home has risen above a certain level.

This can be useful in some instances, but it’s best to use this setting sparingly—you may not think about how much energy your furnace uses all day long when you leave for work, but if you use the ‘On’ setting during those times, it will cause your bill to skyrocket.

It’s also important to keep in mind that using this setting can result in an uncomfortable environment for your family; by keeping air circulating throughout the house at all times, you risk raising humidity levels and making everyone feel stuffy and humid as they try to relax or sleep at night.

Thermostat Fan Mode On

This is especially true during winter months: when temperatures outside are cold enough that people tend to keep their windows closed while they’re asleep or away from home (like at work), leaving them open overnight won’t make much of a difference because outdoor conditions won’t change much overnight anyway.

However, if indoor temperatures rise high enough thanks solely on purposeful control (via an always-on fan), then there’s no need anymore! The benefit here would have been lost already – instead now both inside AND outside temperatures are higher than usual

What Setting is More Efficient?

As we’ve seen, auto is more efficient than “on”. With “on”, you’re unnecessarily heating the entirety of a home (that very well might be empty or already perfectly heated). This is a waste of energy and money and ends up being “overkill” in regard to each of those resources.

Thermostat Fan Mode Auto

If you live in a very hot area where temperatures are consistently above 80°F (26°C), setting the fan to auto will turn off your furnace more often than it should be, wasting energy and costing you more money. In this case, set it to “on”. But if winter temperatures regularly dip below freezing or even just into the 40s (4-10°C), then an auto setting is ideal because it will keep the heat turned on when there’s no one around to enjoy it.

This is because with an auto mode there’s no need for a person at home—so if someone leaves for work early or comes home late but leaves their heat turned off, they won’t waste any energy heating up their empty house unnecessarily!

What Setting is More Cost Effective?

There are a few reasons why you may want to set your home’s furnace fan to “auto.” For one thing, it will generally cost less money to run the fan when it’s running on auto rather than on.

Also, when you’re using a thermostat with an ‘auto’ setting for your furnace fan, you’ll have better control over other areas of the house that are also controlled by the thermostat (like lighting).

Additionally, there are some benefits from using an ‘on’ or ‘auto’ setting for your home’s heating unit in general:

  • If your house uses natural gas as its primary source of heat, then running a ceiling fan above the stovetop during cooking can help circulate more heat throughout the room. This can make cooking easier and more comfortable—especially if someone else is also cooking at another stovetop in the same room!
  • Using fans while sleeping helps keep air circulating through bedrooms so that temperatures don’t become too stagnant overnight (which can lead to stuffy noses). And while they might not be able to keep body temperature at ideal levels during sleep periods where extreme temperatures occur outside–like winter months–they do help break up milder episodes of overheating during summertime months as well!

What Setting is Less Tolling on the Furnace?

In general, the ‘auto’ setting is less taxing on your furnace.

This is yet another reason to make great use of the “auto” setting.

The reason for this is that it only activates when the thermostat has determined that it needs more heat. This means you’re burning less fuel, which saves money and reduces pollution.

The ‘auto’ setting also maintains a more consistent temperature throughout your home. If you use the ‘on’ setting, there’s a chance that some rooms may be cooler than others if they don’t get enough air from vents in those spaces (especially if some doors are closed).

In case you aren’t completely convinced at this point, here’s one more reason to choose the “auto” setting during winter:

What Setting Should You Use?

You’ll save the most energy by using the ‘auto’ setting.

This will allow your furnace to heat your home as needed, without running when it isn’t needed.

You’ll also save money by using the ‘auto setting. This should be used if you want to run your furnace fan constantly during freeze warnings or periods of extreme cold weather. You can set up a timer so that it only runs for a certain amount of time each day and then turns itself off automatically (but still has power ready if you need it).

You’ll save time by using the ‘auto’ setting, which allows you to set up a schedule for when you want your furnace fan on and when you don’t need it at all.

Thermostat Setting


If you’re still wondering whether to set your furnace fan to ‘on’ or ‘auto’ mode, we can help.

The most efficient setting for your furnace is the auto mode, which will turn on and off automatically based on the temperature in your home. This setting also doesn’t cost any more money than other settings because it uses less energy overall throughout the year. If you want to save money while also being kinder to the environment, then this is a great option!

Overall, “auto” seems to be the preferred mode for energy efficiency, cost, and convenience. It is with this mode that a homeowner doesn’t have to worry about constantly fussing over temperatures and guessing when to adjust, because the automatic setting is doing the work for them.

We’re confident that after reading this article you’ll be able to make the best decision as to how to best heat your house in a way that works best for you.

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