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Clean or Replace Furnace Filters Once a Month or as Recommended

Clean or Replace Furnace Filters Once a Month or as Recommended

Wisconsin homes require regular upkeep and maintenance throughout the year. Changing furnace filters is one critical task that is often skipped – to the detriment of your comfort and the performance of your home’s heating and cooling equipment! With a dirty filter in place, you risk compromising your comfort, energy costs, and HVAC system.

From heating and cooling system maintenance that ensures a clean filter to HVAC repair that counteracts the problems caused by a dirty one, we provide the services you need for a comfortable home year-round. 

What Does a Furnace Filter Do?

Your furnace filter traps airborne contaminants to clean your air, right? While yes, it does do that, that’s not exactly its job – despite what most people believe.

The primary function of a furnace filter is to trap airborne contaminants not for air quality purposes, but to keep them out of your heating and cooling system. However, because the filter removes contaminants for the system’s benefit, air quality also benefits from their removal.

How Often Is Changing Furnace Filters Necessary?

Changing furnace filters is a job that’s frequency varies from one house to the next. How often this task needs to be performed is greatly dependent on the type of furnace filter in place. If you have a peak down the filter replacement aisle at your favorite hardware store, you’ll see there are a lot of options to choose from – lots of different filter types to impact changing frequency.

Changing furnace filters needs to be completed every month to every year – just like there is a great range of filters, there’s a pretty wide range to how often they need to be replaced. Luckily, changing furnace filters doesn’t depend on a guess. The filter’s manufacturer provides the recommended replacement frequency within the product information that’s included when you buy a new filter.

To give you a starting point for what frequency you’re looking at for changing furnace filters, size matters. Thicker filters have more media available to capture contaminants, so a 5-inch filter requires less frequent changes than a 1-inch filter. Filter efficiency also has an impact – this is expressed as MERV, which stands for minimum efficiency reporting value.

In general, this is how often changing furnace filters needs to be done:

  • For 1- to 2-inch filters, replace them every 1 to 3 months
  • For 3- to 4-inch filters, replace them every 6 to 9 months
  • For 5- to 6-inch filters, replace them every 9 to 12 months

More Factors that Affect Frequency of Changing Furnace Filters

As we mentioned, size and efficiency are two attributes that affect the frequency changing furnace filters is performed. In addition, there are various factors specific to your Cincinnati area household that have a greater impact on how often you really need a new filter.

Home Occupancy

The number of people living in a home affects the useful service life of a furnace filter. In a large household, changing furnace filters is done on a more frequent basis than homes with just one or two occupants. People introduce many contaminants to the home environment, so the more people there are in your home, the more contaminants there are for the filter to catch.

Furry Family Members

Pets are another major contributor of contaminants into the indoor air supply. Pets shed fur and dander, which are picked up by airflow and circulated throughout the home by the HVAC system. For every furry family member living in your home, a filter’s useful service life is reduced by approximately 30 days, so you’re changing furnace filters more often.

Indoor Air Quality

If you have air quality issues present in the home, your furnace filter isn’t going to last as long as it does in a home with good indoor air quality. Indoor air quality equipment like air purifiers and air cleaners reduce contaminant volume so there’s fewer particles for your furnace filter to capture – in homes without this equipment, the furnace filter is the only line of defense against airborne contaminants, so the filter fills up faster. 


If members of your household suffer from allergies or asthma, changing furnace filters should be done on a more frequent basis. Doing so helps ensure contaminants that cause symptoms are removed from your indoor air supply.

Heating & Cooling Usage

When your home’s heating and cooling equipment is heavily operated, filters have a shorter useful service life – air is circulated more frequently, so the filter has more opportunities to pick up contaminants and become clogged. In the summer and winter, homeowners are typically changing furnace filters more often than they are in the fall and spring.

Dirty Furnace Filter Disasters

When changing furnace filters is forgotten or skipped, various problems arise in Cincinnati households. Dirty furnace filters spell disaster for heating and cooling equipment, home comfort, and indoor air quality.

HVAC System Damage

  • Heating and cooling equipment like furnaces and air handlers are filled with many delicate components. Without filtration, airborne dust, dirt, and other debris enters the various chambers of the unit and settles on its components. Contaminants accumulate and worsen the performance of the equipment, even causing damage to components.
  • When filters are clogged but the HVAC system continues to run, air doesn’t move through the system properly. With the dirty filter blocking its path, heating and cooling equipment expends more energy to push air along. This extra work stresses the system’s components, using more energy and damaging equipment.
  • Airflow blockage caused by a dirty filter raises the temperature within the HVAC equipment, causing it to overheat. After it cools, it starts back up again, but the problem persists – this is an issue known as short-cycling, and dirty filters are the most common cause. Short-cycling leads to HVAC system damage that requires repair and early total system failures, in addition to excess energy consumption, higher utility bills, and diminished indoor comfort.
  • As contaminants flow through the HVAC system due to a dirty filter, they collect within the condensate drainage components and clogs form. Clogs stop condensate from draining out of the home, and it may spill over which results in water damage to HVAC equipment and nearby areas. Plus, excess condensation increases indoor humidity levels which disrupts comfort.

Poor Comfort & Air Quality

  • Because airflow is restricted when changing furnace filters is forgotten, living areas do not receive the proper amount of heating and cooling. It becomes hard to maintain comfort levels and homeowners often notice hot and cold spots.
  • When the filter is covered in contaminants, there is no more surface area left to trap new contaminants passing through. Therefore, those contaminants remain in the air supply and move back into your home where they cause allergy symptoms, respiratory issues, bodily irritations, and dirtier surfaces no matter how frequently you clean!

Never Forget Another Filter Change!

Changing furnace filters is so very important, not just for your HVAC system but for your household. It’s all too easy to skip a filter change when your HVAC equipment is tucked away out of sight, but this important task must be made a priority.

It’s smart to check your filter monthly to assess its condition. Sometimes, your system may require changing furnace filters early, but it’s difficult to tell if you never look for yourself! Take a peek at the filter once a month and replace it when you notice its surface media is completely covered in contaminants.

Because changing furnace filters is so important, here are a few strategies to help ensure you remember to perform this essential home maintenance task.

  • Mark monthly filter checks as well as changes at the appropriate interval on your wall calendar or within your day planner.
  • If you prefer your smartphone’s calendar app, schedule reminders with an alarm that sounds to catch your attention. 
  • Link checking and changing furnace filters with other important tasks you complete each month. As the filter’s condition can impact how much energy the system consumes, check it when you pay your monthly utility bill! Do not file that bill away until you check or change your filter.

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