How Often Should You Change Your Furnace Filter?

Clean furnace filter vs. dirty furnace filter

If you live up north, a well-functioning furnace can be the appliance that turns a house into a home. It’s not only essential for frosty winters, but it’s vital for lower utility costs and healthy living.

Because the functionality, performance, and longevity of your furnace hinge on how often you replace its filter, Hoffner Heating and Air Conditioning created this at-a-glance guide. From health consideration to replacement timelines, we’ve taken an in-depth look at filtration best-practices.

The Importance of Your Furnace Filter

All of the air that circulates through your home’s HVAC system passes through your furnace filters. They remove dirt, pollen, allergens, bacteria, and other air pollutants. Clean filters also keep dust from building up in your home’s ductwork. Without a filter, you and your family would be breathing in all of that harmful particulate.

Dirty air filters force your furnace’s fan to work harder to push air through the system, which can shorten the life of your unit. Eventually, clogged filters can cause the sensitive HVAC system itself to malfunction, causing permanent damage.

Clogged filters can also cost you money as they prolong heating and cooling cycles, leading to higher energy costs. According to the Department of Energy, routinely replacing your air filters can lower your air conditioner’s energy consumption by 5-15%.

More importantly, dirty air quality can affect your health. According to the Environmental Protection Agency, “the air that we breathe in our homes, in schools, and in offices can put us at risk for health problems.”

The EPA estimates that the air inside our homes can be up to five times more polluted than the air we breathe when we’re outside. If you’re not changing your air filter regularly, you’re not allowing it to do its intended purpose of purifying your home’s air.

Rules for Replacement

First and foremost, check with your furnace’s manufacturer to see what they recommend and what size filter your furnace needs. To find out what size filter to buy, simply remove and examine the current filter.

The size should be listed on the filter’s frame. You can also check your furnace’s owner’s manual for the correct size to purchase. Manufacturers usually design furnaces to use only one size of filter. In general, the thinner your furnace filter is, the more often you will need to change it.

Here is how often you should replace your air filter:

  • 1″ Furnace Filter: 1 – 3 Months
  • 2″ Furnace Filter: 1 – 3 Months
  • 3″ Furnace Filter: 6 – 9 Months
  • 4″ Furnace Filter: 6 – 9 Months
  • 5″ Furnace Filter: 9 – 12 Months
  • 6″ Furnace Filter: 9 – 12 Months

Remember, these are just guidelines; there is a multitude of factors that affect your home’s air quality. For this reason, it’s a good idea to periodically inspect your furnace filter, even if you’ve recently changed it. If it is covered in buildup, replace it. If it seems like you’ve just cleaned the house and your home’s surfaces are dusty again, consider changing the furnace filter and consulting an HVAC professional.

If outside temperatures are extremely cold or hot and your furnace or air conditioner is running nonstop to keep up, filters that should have lasted for 90 days will have to be changed every 30 days to ensure your HVAC system functions properly.

Special Considerations That Necessitate more Frequent Filter Changes

  • Larger homes: Furnaces in bigger homes need to circulate massive amounts of air, which means you may need to change your filter more often to keep up with increased demand.
  • Outdoor Air Quality: If you live in a metropolitan area, the air in your home may be more polluted with smog and outdoor emissions. Urban living can place more of a demand on your filter.
  • Asthma and Allergies: If anyone in your household has asthma or allergies, you’ll need to change the air filter more frequently to mitigate the likelihood of flare-ups.
  • Respiratory conditions: Likewise, if household members have respiratory problems, such as chronic obstructive pulmonary disease or emphysema, you should err on the side of caution and change your furnace filter more often.
  • Pets: If you have a cat or dog, your filter will work harder to keep up with the copious amounts of fur and dander that they shed. Outdoor pets also track in outside dirt. The more pets you have, the more often you will need to replace your filter.

On average, Americans spend 90% of their life indoors. What could be more important than ensuring your home’s air quality is as pure as possible? When in doubt, go ahead and replace the filter.

Is There a Smoker in The House?

If you have smokers in your home, you’ll need to replace your furnace filter more frequently. The more smoke, the shorter the lifespan of each filter will be.
If there is only one smoker, you can generally get away with changing a one or two-inch filter every two months.

However, your best plan of defense is not to smoke indoors (or at all for that matter). That being said, if you do smoke, you need to ensure your air filters are clean for you and the rest of your family members.

Want Help With Your Heating and Cooling Needs?

If you’d like to learn more about furnace maintenance and want a professional HVAC specialist to help you ensure your system is running effectively, contact Hoffner Heating and Air Conditioning today. We also offer annual service checks. Whether you need a complete system installation or maintenance and repair, we’re always here to help.