Hack for Summer: Can Running Furnace Fan Cool House?

Ah, summer! Vacations, sun, and…heat.

While I love the sun and warmth of summer, it can rack up energy costs to keep my house cool enough during these months.

I love looking for ways to improve the efficiency of my home and keep it more comfortable, without breaking the bank in the process.

Take, for example, the furnace. Most furnaces have fans that can be run on their own.

I’ll let you in on a little secret: the fan function that most furnaces have can actually be used in the summer to cool down your house.

Is It Okay to Run a Furnace Fan Constantly?

Contrary to what I originally thought, constantly running a furnace fan is safe for your furnace’s longevity.

Furnace professionals say that regularly running your fan is actually better for your motor than letting it go for long periods of time between uses.

There is some indication that running constantly can increase the lifespan of your furnace motor.

Why, you ask? (Me too…)

Apparently, the motor gets the bulk of its wear and tear during the starting of the furnace. (This is similar to how vehicle motors work.)

Running the fan continuously will help reduce the number of times it has to go through its start-up process, which is the most taxing part of operating the furnace.


Is Running a Furnace Fan Efficient?

Yes, it actually is.

If you have a central air conditioner, using the furnace fan can actually reduce the amount of air conditioning you need to use to keep your home comfortable.

It is important to remember that hot air rises, so for people like me who live in multi-story homes, this can be a real energy saver.

Running the furnace fan can help to draw hot air from the upper floors of the house, pushing it outside, reducing the indoor air temperature significantly, which will, in turn, reduce the amount your air conditioner will need to run.

If you don’t have central air, this is still a great idea if you live in a multi-story house.

This can make the upper floors of the home more tolerable during the summer.

In tandem with other fans or air conditioning, a furnace fan can help keep your home cooler and help save on utilities.

Does Running a Furnace Fan Bring in Outside Air?

While a forced air furnace may use outside air in the combustion process, it does not bring outside air into the house.

If the air used for combustion did come into the house, it would bring in dangerous carbon monoxide.

There is a furnace filter that cleans the inside air as it recirculates, keeping the air in your home healthy and safe to breathe.

Should You Run Your Furnace Fan in Summer?

Do you want a cooler home and lower energy costs? Then the answer is yes!

The furnace fan function takes some of the burden from your air conditioner, sharing the cooling job and saving energy.

By running the furnace fan, you not only help to reduce the indoor temperature, but you also help keep the temperature more stable throughout the home.

Running the furnace fan in the summer can help reduce the chances of having indoor hot spots, or places in your home where it is significantly hotter than in other places.

Proper circulation not only helps to maintain a steady temperature, but it also keeps the indoor air quality better. The breeze that occurs when a fan runs also helps make the air temperature more comfortable as well.

This works best in milder climates, but furnace fans can be useful in any climate where you might have a furnace.

How to Make a Furnace Fan Run in Summer

How to Make a Furnace Fan Run in Summer StepsMany furnaces have an auto fan setting that only kicks on when the heater is running.

You will want to turn this auto setting off and choose the fan-only setting.

Most furnaces have the following options: manual, automatic, and off.

Automatic is what I described above.

“Off”, as the name implies, simply turns the fan off completely.

The manual setting will allow you to control the furnace fan through your thermostat.

Another easy way to do this is to install a summer switch.

This toggle switch is easy to install and attaches to the furnace.

When you turn the summer switch on, the fan will run continuously.

In Closing

Heating and cooling represent the biggest operating costs in my home, and I’m sure I’m not alone in that.

With some creativity and thinking outside the box, I’ve gotten around some of these expenses.

Furnace fans are a lot more energy-efficient than air conditioners are and can reduce your need to use an air conditioner in the first place, especially if you live in a milder climate.

The added bonus of air circulation will also help improve the quality of your air.

Combining air conditioning or other fans with a furnace fan reduces the amount of energy you use.

Running the furnace fan is a great hack to keep your home cool in the summer.

8 thoughts on “Hack for Summer: Can Running Furnace Fan Cool House?”

  1. Good article in general. Thank you.

    I do think you are confused about outside air. Our central forced-air furnace uses outside air only for combustion, and that is sealed off from the inside house air — they should not mix.

    Also, running the fan does filter the home air, so recirculating may be cleaner than outside air on some smoky days. (You may be remembering that this is NOT true in the smaller volume of air in a car, where outside air is essential to offset the humidity from our breathing.)

  2. Stephanie, I have a correction for you regarding the furnace fan for summer use.
    I just discovered this problem myself on my own home, and it is important. If you set the fan to ON when using your A/C, the humidity in the house will not go down at it should; instead, the water that condenses on the chilled A/C coil in the furnace will simply be “re-evaporated” by the warm air being blown over it and redistributed through the house.
    I was using that ON setting for years and could not understand why I couldn’t get the humidity level in the house below 70%–which was far too high. I had seen numbers as high as the low 80% range!

    Just this week I heard a gentleman on the radio describe the exact same condition in his home and how an HVAC guy immediately knew that this was due to his furnace fan setting.
    Sure enough, both he and I changed the setting to AUTO and the humidity level in our homes has dropped very quickly into the much healthier range of 50%.
    Yes, this has caused my upstairs to now be a little warmer due to less air movement, but the humidity level was simply not healthy as high as it had been. I could hardly believe how long I had had this problem,… and then how simple the solution actually was.

    Kind Regards,
    Steve S.
    West Chester, OH

  3. Hi, I live in California and I’m suffering from a heat wave and I don’t have central air, Should I use my Furnace Fan to keep my home nice and cool when it’s hot and stuffy outside?

    • Hi Mike, Yes, using your furnace fan should help cool your home, by reducing the work your air conditioner has to do. Because your heat is so extreme, you may not notice a huge difference, but it’s definitely worth trying! Let us know how it goes. 🙂


Leave a Comment