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December 21, 2018
Here at Kearney HVAC, we understand how complex a home’s heating and cooling systems can be. That’s why we’re here to answer your questions and offer homeowners along the North Shore of Massachusetts peace-of-mind installation and maintenance services. One question we often hear from local homeowners has to do with one simple furnace feature: the furnace fan. Our customers ask, “Should I set the furnace fan to ‘on’ or ‘auto’ in the winter?”
Our answer is: it depends. Here’s a quick look at the benefits of running the furnace fan at each setting — and how you can decide which setting is better for your home.
Pros to Running the Fan All the Time
Better Air Circulation
The most obvious benefit to keeping the furnace fan on the “on” setting is more even heating and cooling distribution. Heat has a tendency to rise in the home during the winter due to “stack effect,” and parts of the home that see greater sun exposure may also become warmer than the rest of the house. The furnace fan helps circulate heat throughout the home to eliminate hot and cold spots — kind of like a convection oven.
Healthier Indoor Air
Keeping the furnace fan on also has the potential to boost indoor air quality (IAQ). This is because running the fan pulls the air through the filter and UV light system, if you have one. Of course, you’ll need a high quality filter in place to ensure that running the fan actually does make your indoor air cleaner.
Reduced Wear & Tear
Furnace fans are designed to run all the time, so there’s no need to worry about it failing prematurely. Much of a furnace fan’s wear and tear comes from the starts and stops of the motor; keeping it running can eliminate this type of stress.
Pros to Running the Fan on “Auto”
If you have an older, less efficient furnace, it could be cost-prohibitive to keep the fan running all the time. Setting the fan to “auto” may be more cost-effective and use less energy. (Of course, the downside here is that there will be less even air distribution throughout the home.)
Longer Lasting Filter
As we just mentioned, the furnace fan pulls air through the furnace’s filtration system, promoting cleaner indoor air. The flipside to this is that you can expect your furnace filter to become clogged and dirty more quickly. If you don’t have any family members with allergies and indoor air quality isn’t a major concern to you, you may prefer setting the fan to “auto” to extend the life of your furnace filters.
Which Setting Is Better for You?
Ultimately, which setting you choose for your furnace fan is up to you. If you are looking for ways to enhance IAQ and create more consistent indoor comfort, keeping the fan running is the way to go. If, on the other hand, you are away from home for most of the day and know your heating system is less energy efficient, perhaps you’d prefer the slightly lower running costs that come with the “auto” feature.