How often should you change your furnace filter? The typical answer is every 90 days (three months). However, each home is exposed to different conditions which affect the proper time for filter replacements. Every homeowner knows their furnace filters needs changed as they affect the home’s air quality and efficiency of the furnace. Nevertheless, many don’t keep a regular filter replacement schedule that’s suitable for their home.  In order to keep harmful debris away from the furnace, you need to know what your filter is dealing with. If a filter is left forgotten and unchanged, it can lead to a myriad of complications.

What Problems Can a Dirty Furnace Filter Cause? 

As a furnace needs air for many functions, it will strive to keep the proper amount of airflow. Even to the point of over-stressing and blowing out the motor. More often than not, dirty filters create situations where the lifespan of a furnace is shortened to the point of needing repairs or a replacement. Besides overworking and causing an expensive piece of equipment to break down, dirty furnace filters can also cause problems like: 

  • Higher Energy Consumption: Studies show the longer a furnace runs with a dirty filter, the higher monthly bills rise. Homeowners can save around 15% on energy consumption simply by keeping a regular filter schedule! 
  • Lower Air Quality: Since the filter is already dirty, it isn’t able to do its job to remove airborne pollutants properly.  Instead the ventilation system redistributes these particles back into the air. This can further intensify allergies, asthma, or other respiratory conditions.
  • Faulty Equipment and Health Hazards: If a filter’s condition deteriorates far enough, it can actually cause the furnace to shut down. The furnace needs proper airflow to disperse the heat throughout the house. If it’s unable to do so, the safety feature will trigger and shut off the furnace. This safety feature is the limit switch, which will activate when the furnace’s temperature surpasses a certain level. By doing so, it keeps important parts like the heat exchanger from overheating, breaking, and leaking carbon monoxide.

What Does a Dirty Furnace Filter Look Like?

So how do you know when a furnace filter is actually dirty and needs replacing? Categorize your furnace filter into one of these four groups:

  • New/Just Installed: No dirt build-up with white coloration
  • Working: During the first couple months, a thin layer of dust and dirt will start forming on the filter. This layer of dust will cause the filter to look gray or brownish. This accumulation is totally normal and means the filter is working properly.     
  • End of Life: Visible dirt and small clumps of dirt/dust/hair in places, creating a thick, gray layer. If you can pick off the dirt clumps, then they can be eventually dislodged and redistributed throughout the house. To keep from inhaling those particles or causing problems with the furnace, it’s time to replace the filter.
  • Past Due: Homeowners should replace any filters with a thick dirt cover, large dirt clumps, mold growth, or dead bugs immediately. A filter needs replacing even if there are just large dirt clumps as that is where bacteria and mold thrive. If mold spores develop, they can be moved throughout the house, causing health problems. 

How Often Should You Change Your Furnace Filter? That Depends on These Factors

  • Filter Type: The filter type is often the determining factor when setting a schedule to change out filters. The main filter types are fiberglass and pleated. While they both are disposable types, pleated filters have a longer lifespan due to the larger surface area.
  • Home Size: Simply put, larger homes have more air volume to run through the filter and clean. More air typically means more dirt which can cause filters to need a different replacement schedule than those in smaller houses.
  • Outdoor Air Quality: The surrounding environment or events, like wildfires, that affect the environment’s condition also have an impact on indoor air quality. Harmful pollutants like smoke, smog, or other debris can seep into the home. This produces more dirt and debris for filters to catch, creating a faster replacement rate.
  • Pets: In addition to their own fur and dandruff, pets can also track-in pollutants from outside such as dirt, pollen, mold, and more. Compared to homes without any pets, those with pets will find they have to change filters more frequently
  • Allergies: For those who suffer from allergies, asthma, or other respiratory conditions, actually replacing the filter more often can help lessen symptoms. Simply by changing the filter before its end of life can help everyone in the family breathe better.
  • Visually Dirty: The easiest way to determine how often should you change your furnace filter is to simply check its condition. As a filter becomes dirty, make note of how long it takes before noticeable (and removable) dirt clumps form. Another way to know when the furnace needs a filter replacement is by using a light source. If the filter doesn’t allow light to pass through, it’s also unable to let adequate airflow through.

Your Local MO Heating Contractor 

Occasionally problems happen due to forgetting to change the filter. So if your furnace stops working or something seems off about your heating system, contact Satterlee! Our furnace repair professionals are experienced in handling all your heating problems by:

  • Thorough inspection for clogs within the ventilation system
  • Examining critical furnace components (heat exchanger, belts, blower motor, flame sensor, and more) to see if any are in need of replacement due to damage
  • Ensuring the blower components are in working order and cleaning it if necessary 
  • Inspecting all electrical connections and wiring and replacing any damage
  • Analyzing the thermostat and recalibrating if necessary 
  • Testing all the safety features to ensure the furnace is working properly and safely

Our expert technicians will work to quickly diagnose and pinpoint the cause of the issue. After examining the extent of the damage, we’ll suggest what needs to be repaired or replaced.  Then offer preventative measures to help you avoid that problem in the future.