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How Often Should You Replace Your Furnace Filter?

Written by Craig Aspinall | Aug 8, 2025 5:38:54 PM

Imagine walking into your utility room and noticing your furnace working harder than usual. The air feels stuffier, your energy bills seem higher, and family members with allergies are frequently complaining about symptoms. You peek at your furnace filter and realize you can’t remember the last time you changed it. Sound familiar?

If you’re wondering how often you should replace your furnace filter, this guide will help. The answer varies based on several factors specific to your home and lifestyle, but understanding the basics will help you create a replacement schedule that works for you. Here’s what you need to know about this simple maintenance task that can improve your home’s comfort, air quality, and energy costs.

Understanding Common Types of Furnace Filters

Furnace filters are like the guardians for your heating system. They capture dust, pollen, pet dander, and other airborne particles before they circulate through your home or clog up your furnace components.

These manufactured home furnace filters offer varying levels of protection and require different replacement schedules.

  • Fiberglass filters: The most basic and affordable option, these disposable filters catch larger particles but can miss smaller ones.
  • Pleated filters: Made from polyester or cotton, these accordion-style filters trap more particles and often last longer than fiberglass.
  • HEPA filters: These high-efficiency filters capture nearly 100 percent of particles, which is ideal for family members with severe allergies or asthma.
  • Hoghair filters: These filters feature natural fiber filters that provide good airflow while catching medium-sized particles.
  • Foam filters: Foam filters are a washable option that a household can clean and reuse multiple times.

Filter efficiency gets measured using MERV ratings (Minimum Efficiency Reporting Value), which range from 1 to 20. Higher MERV ratings mean better filtration, but these filters can restrict airflow if used in furnaces designed to handle different ratings. Manufactured home furnace systems often work best with MERV ratings between 6 and 12, but you can check the manual or contact your furnace installer to be sure.

General Recommendations for Filter Replacement

Most experts recommend replacing furnace filters every 1-3 months, but this is a guideline rather than a hard rule. For instance, basic fiberglass filters may need replacement every 30 days, while higher-quality pleated filters can last 60-90 days.

If you’re not sure how long ago the last replacement was, you can visually inspect the filter. Remove the filter and hold it up to a light source. If you can’t see light passing through easily, or if the filter looks gray instead of white, it’s time for a new one. Filters should feel relatively light when clean—heavy, clogged filters restrict airflow and force your furnace to work harder.


Other Factors Affecting Filter Replacement Frequency

Several factors influence how quickly your filters accumulate debris and need replacement.

Local Air Quality Conditions

Your home’s location significantly impacts filter lifespan. Manufactured homes positioned near these environments may need more frequent filter replacements:

  • Gravel roads
  • Construction sites
  • Agricultural areas
  • High-traffic zones

Homes in cleaner suburban or wooded areas may extend replacement intervals slightly.

Pets

Furry family members can increase filter replacement needs. Dogs and cats shed hair and dander, which then becomes airborne. Homes with multiple pets or breeds that shed heavily, such as golden retrievers or Persian cats, will need to replace filters more often.

Occupant Sensitivity

Family members with allergies, asthma, or other respiratory conditions require cleaner air. These households should change filters more frequently than the recommended interval, especially during peak allergy seasons.

Furnace Usage

Heavy furnace usage means that more air is passing through your filter system. During cold winter months, when your furnace constantly runs, filters accumulate debris faster. Track your usage patterns and adjust replacement schedules accordingly.

Filter Type

Different filter materials have varying lifespans:

  • Fiberglass: 30 days maximum
  • Pleated: 60-90 days
  • HEPA: 6-12 months (depending on conditions)
  • Foam or hoghair: Clean every 30 days, replace annually

Step-by-Step Guide to Replacing a Furnace Filter

Replacing your furnace filter takes just a few minutes with the right approach.

Safety first: Turn off your furnace at the thermostat and the main power switch. This prevents the system from running while the filter compartment is open.

Locate the filter: Find the filter compartment, usually located behind the furnace door.

Remove the old filter: Slide out the old filter carefully to avoid shaking loose debris back into your system. Note the airflow direction arrows printed on the filter frame (if applicable).

Install the new filter: Insert the new filter and make sure it fits snugly without gaps around the edges. If you’re using a roll-type replacement filter, you may need to cut it to size so that it fits securely behind the furnace door.

Disposal and cleanup: Dispose of the old filter in regular trash. Vacuum any debris from the filter compartment before closing it up.

Restart your system: Turn your furnace back on and verify normal operation.

For foam or hoghair filters, wash them with mild soap and water, let them dry completely to prevent mold growth, then reinstall. Replace foam filters annually.

Benefits of Regular Filter Replacement

Consistent filter maintenance delivers multiple advantages for your home and wallet.

  • Clean filters improve energy efficiency by allowing proper airflow through your system. Restricted airflow forces your furnace to work harder, consuming more energy and increasing utility bills.
  • Fresh filters dramatically improve indoor air quality by removing allergens, dust, and other irritants. Family members with respiratory sensitivities may notice improvements within days of installing clean filters.
  • Regular maintenance extends your furnace’s lifespan by preventing debris from accumulating on internal components such as the heat exchanger, blower motor, and other sensitive parts. Clean systems experience less wear and tear, reducing repair needs and delaying expensive replacement.

Remembering To Replace Your Furnace Filter: Tips To Try

Creating a reminder system helps you stay consistent with filter maintenance. Use our strategies to maintain a consistent schedule.

  • Set monthly calendar alerts on your phone or computer. Choose a specific date (like the first of each month) to check your filter condition.
  • Write filter change dates on a wall calendar near your furnace. This visual reminder helps you track replacement patterns and identify seasonal trends.
  • Combine filter checks with other routine maintenance tasks like testing smoke detector batteries or cleaning gutters. Grouping tasks makes them easier to remember and complete.
  • Buy filters in bulk and store them near your furnace. Having replacements readily available eliminates the excuse of not having a new filter when you need one.

Keep Your Home Comfortable With Regular Maintenance

Regular filter replacement is one of the simplest and most effective ways to maintain your home's heating system. The small investment in new filters pays dividends through lower energy bills, cleaner air, and reduced repair costs.

Remember that the question of how often you should replace your furnace filter doesn’t have a one-size-fits-all answer. Your specific situation—including pets, air quality, filter type, and system usage—determines the ideal replacement schedule. Start with monthly inspections and adjust based on what you observe. If it’s time for a service call or to order replacement furnace filters, Capitol Supply & Services can help.