How often should I run the fan on my furnace?

After learning about how to get their furnace ready for the winter months, homeowners often want to know if they should run the fan even when the furnace isn’t heating and moving the air. As with most debates, there are two sides to every story. Let’s look at some of the pros and cons of running the fan on your furnace all the time.


Running the fan all the time can even out cold and hot spots within your house. This is especially useful for multi-story homes where hot air can collect in the upper levels causing large temperature variations. Running the fan can serve to pull hot air down the stairs while circulating cool air through the upper rooms of the house.

Running the fan at all times has the added benefit of providing constant air filtration. This is a great way to help provide relief from allergies, asthma, and other respiratory ailments. Couple this with a high-performance filter and you’ve got a great method for cleaning the air in your house all day long.

Some speculate that running the fan at all times can actually extend the lifetime of the blower motors on furnaces. This is because the stop and start of normal operation can be the most stressful time for any motor. By running the fan all the time, the motor is – theoretically – subjected to less stress (the stops and starts) and may last longer as a result.


The major drawback to running your fan all the time is the increase in energy use which isn’t good for the environment and which can drastically impact your wallet.

Some speculate that running the fan at all times can cause the fan to wear out sooner because of the constant use.

When you think about it, manufacturers build the fans to stop and start. If they thought it was a major problem, they wouldn’t put the Auto feature on their furnaces bound for Calgary.
Ultimately though, the choice is up to you about whether to run the fan on your furnace in Calgary at all times. If allergies are not a problem and you’re not concerned with – or haven’t experienced – cold or hot spots in your house, they you might choose to set your fan to Auto and let the furnace control when it comes on. If allergies are a major concern or the hot/cold spots in your house have some wearing sweaters and others wearing shorts – and you’re not concerned about the cost – you might choose to run the fan on your furnace all the time.

If you want to experiment for yourself, try each method for a month and see which you prefer. Be sure to keep track of your utility bill so you can compare what each method does to your wallet. It’s also a good idea to let the other people in the house know what you are doing so that they can keep track of how they feel (and how each room feels) when the methods change.

Having said all that, we do NOT recommend running the fan all the time – neither in the summer nor in the winter. Here’s why:

In Calgary, all newer homes have a fresh air intake. This intake is typically a 5 inch pipe that brings air from the outside and pumps it into the return-air side of your furnace. Anytime the furnace is running, you are sucking air from directly outside. So if that air is +30 and muggy, you are going to make your house much hotter. If that air is -30 and freezing cold, it’s like trying to heat your home with a window open. From a comfort standpoint, it might be beneficial, but from an energy-saving standpoint (by that we mean electricity and gas), it’s very detrimental.

We have seen many homes left unoccupied during the winter (owner goes on vacation, for example) with the fan running all the time. At some point during the owner’s absence, the burners fail to ignite (because of a faulty gas valve, for example) but the fan continues to run and pump freezing cold air throughout the house. It’s easy to see that a home could freeze up very quickly under these circumstances.

If you have any questions about how to properly run your furnace fan or any questions regarding your home comfort needs, please call us at(403) 477-3810. We would be happy to spend some time talking with you.

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24/7 Emergency Service!
Call 403-477-3810
or Fill Out Our Online Form
HOURS:   Mon - Fri: 8AM - 5:30PM
24/7 Emergency Service Available
PHONE:   403-477-3810
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