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How Often Should You Change Your Furnace Filter?

Signs that you need to change your filter and the factors that cause it to accumulate dirt quickly.


The amount of time the HVAC units run varies in every home. Additionally, each house has different levels of dust, dirt, allergens, and pet dander in the air. So, the amount of times you change your furnace filters depends a lot on these factors.

However, a common rule is to replace the filter depending on its size: every three months for 1-2-inch filters. For 4-inch filters, they must be replaced every six months and every 12 months for 5-inch filters.

Below are some signs that you need to change your filter and the factors that cause it to accumulate dirt quickly.

Signs That You Need to Change Your Filter

      ● It’s visible that your filter is dirty. If your filter is already covered with dirt, you should replace it as soon as possible.
      ● Your home is dustier than usual.
      ● Your cooling/heating system runs more often than usual.
      ● There is a burning or strange smell near the HVAC unit.

Factors That Affect the Life of Your Furnace Filters

Leaving your doors and windows open allows dust and contaminants from the outside air to get inside your house. If you’re doing this frequently, 1-2-inch filters must be replaced every month, every two months for four-inch filters, and five-inch filters should be replaced in three months.

A) Smoking inside your home dramatically impacts the life of your filter. The more smokers in the family, the shorter the filter’s life will be. Multiple smokers at home have the same impact as leaving your doors and windows frequently.

B) Furry pets living inside your home also contribute to the dirt that is filling your filter. Owning one furry pet could get you replacing your 1-2-inch filter every two months, every four months for a 4-inch filter, and every six months for 5-inch filters. On the other hand, multiple furry pets could lessen the life of your filter by 50%.

C) The duration of your heater fan also affects the life of your furnace filters. Continually running the heater fan could get you replacing your filter every month. Running it less frequently could increase the life of your filter by 50%.

D) If someone in your household has allergies, it’s advisable to replace your filter more frequently. Keep in mind that people with allergies need cleaner air to breathe.

Always remember that these factors play a crucial role in measuring how often you need to replace your filters at home. Having clean filters in your home ensures that everyone living in your home breathes fresh air.

A dirty filter could also affect the life of your HVAC system as it needs to work harder, losing its efficiency in the long run. Moreover, the quality of the furnace filters that you install has an essential role in keeping the air inside your home clean.


Make sure that the filter you have at home is designed to trap possible contaminants such as pollen, mold, bacteria, virus, and smoke, more than just dust. Choose the filters that have high MERV (Minimum Efficiency Reporting Value) ratings as it could filter out micron-sized contaminants such as fibers and smoke particles.

It would be best if you also look for manufacturers that could give you the right filters you need and can deliver it at your home on time, allowing you to replace your filters regularly without the hassle of going out to buy them.



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