How Often To Change Furnace Filters: A Simple Guide to Keeping Your Home & Furnace Happy

Feb 24, 2023

An incredible number of our furnace repair support calls start with a simple question “Have you replaced your old filter with a new filter?”.

Changing your furnace filter can solve a mind-boggling number of problems—it can improve heating, save you money, and clean out airborne dust and particles, improving air quality. 

How often should you replace your filter? Let’s find out:

What do furnace filters do?

Furnace filters are designed to trap airborne contaminants as they enter into your furnace. This serves a dual purpose: It stops the particles from entering into your furnace, and it cleans the air in your household.

When particles enter into your furnace, they can build up. Dust, debris, and other particles can then clog up your furnace, causing substantial wear and tear. They can even cause your furnace to be blocked off from airflow entirely, causing it to stop working. 

How often should you change your furnace filter?

As a rule of thumb, you should change your furnace filter seasonally—every 90 days. Obviously, no one wants their furnace failing on them on a frigid winter’s day in Winnipeg, so we recommend checking your filter every 30 days. You can easily see whether or not the dust and debris caked onto your filter might impede airflow. 

Different filters have different needs

With the “check every 30 days, replace every 90 days” rule in mind, it’s important to know that different filters need to be replaced more or less often. The 90-day rule applies to most “standard” filters—that is, pleated filters with a MERV rating of 6 to 9.

You’re probably scratching your head at this point. Don’t worry—we’re about to explain MERV, pleating, and more. 

Change a dense filter more often

Minimum efficiency reporting value (MERV) tells you how good your filter is at catching airborne pollutants—the higher the MERV, the better the filtration.

Home furnaces usually have filters with a MERV rating of 6 to 12. A furnace filter with a MERV of 6 to 9 needs to be changed less frequently (about every 90 days), while those with a rating of 10-12 should be replaced every 60 days. Thicker filters tend to have higher MERV ratings. 

Flat filter vs. pleated filter

Flat filters must be cleaned every 30 days. Pleated filters have more surface area and are thus less prone to clogging. 

Electronic and washable filters

You may also have electronic or washable filters. Electronic filters are usually a two-part system, and you’ll need to replace the pads of the system every 30 to 90 days—check with the manufacturer. 

Washable filters are a type of permanent furnace filter. They generally need to be washed every 30 to 90 days; check with the manufacturer. We usually recommend washing them every 30 days—there’s no replacement cost, and it’s worth the extra effort to keep your air clean.

Different households may need to change their air filters more often

Your furnace filter helps to improve indoor air quality. A clean filter can dramatically reduce the symptoms of allergies and building sickness, while dirty filters can exacerbate those symptoms. 

Air filter changes for allergy sufferers

People who suffer from allergies should change their filters every 30 days. Doing so reduces the number of airborne contaminants, which can help alleviate breathing difficulties and other allergy symptoms.

Air filter changes for pet owners

Most pets shed fur, and even our feathered friends can leave dander in the air. To remove pet dander, you’ll want to use a filter with a MERV of 8 or higher. Electronic filters can be a particularly good option, both if you have allergies and if you have pets.

A summary of what we’ve learned about changing a furnace filter

While there are several factors that can affect how frequently you’ll change your filter, as a rule of thumb, you should replace your furnace filter every 90 days. You should change your furnace filter more often if:

  • It’s flat
  • It has a high MERV rating
  • You have allergies
  • You have pets
  • The filter’s manufacturer has recommended more frequent changes

Change your filter if you feel your indoor air quality has dipped—we want you to have clean, fresh air. 

A surprising number of furnace “repairs” start by changing the filter—a dirty filter can drastically increase energy costs and make heating your home next to impossible for your furnace.

Sometimes, however, a deeper problem is at play. When that happens, the heating and cooling experts at Provincial can help. We offer furnace repair and furnace replacement in Winnipeg. Whether you need help with your furnace filter or something more serious, we’re here for you. 


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