When Should You Replace Your Furnace Filter?

Clean Filters Improve Air Quality

As the days get shorter and the temperature begins to drop, your furnace is going to start working overtime to keep you and your family warm and cozy all winter long. To help ensure your furnace stays in tip-top shape, your heating bill stays low, and your air quality stays high, fall is the perfect time to inspect your furnace, clean your ducts, and change your furnace filter. 

Why Is Changing the Filter Important?

While a furnace filter may not look that impressive, it plays a vital role. A dirty filter can compromise the efficiency of your furnace, driving up your fuel costs, and compromise the air quality of your home. 

Your furnace pulls in air and heats it before redistributing it throughout your home. This incoming air often contains airborne particles such as dust, pet dander, and pollen. Your furnace filter screens out these particles and ensures the warm air being pumped to the various rooms in your home is clean. 

Over time, this formerly airborne debris builds up on your furnace. If too much is allowed to build up between filter cleanings, the filter may become clogged. A clogged filter means your furnace needs to work harder to force warm air through, using more fuel and driving up your operating costs. A dirty filter is also unable to catch as many particles passing through it, decreasing the air quality in your home.

How Often Should I Change My Furnace Filter?

Natural Resources Canada suggests changing your furnace filter at least once every three months and cleaning your furnace and ducts annually. To help keep your ducts and furnace running in tip-top shape, you may want to consider getting one of Mr. Furnace’s protection plans, which offer discounts on air quality products, including furnace filters.

A good general rule to follow is that you should check your furnace’s air filter regularly (say once a month) and either change it or clean it (depending on what type of filter you have) if it looks dirty or clogged. You should also change your filter if your furnace or air conditioner seems to be running more frequently than normal (since this may indicate the filter is clogged) or you notice any strange smells, particularly a burning smell, near your furnace or coming through your vents.

There are a variety of factors that affect how often your filter needs to be changed. You should change your filter more often than the suggested guidelines if:

  • You have pets. Dogs and cats, in particular, are prone to shedding and generate both pet hair and pet dander. Pet hair, in particular, can clog furnace filters, while pet dander can decrease the air quality in your home. 
  • You or another resident in your home smokes. Smoking indoors increases the number of particulates in your home significantly. This, in turn, decreases the lifetime of your furnace filter. If one or more of your home’s residents smoke, you should check your filter regularly and replace it or clean it whenever it becomes visibly dirty.
  • Someone in your home has allergies. Individuals with allergies, particularly pet allergies and dust allergies, depend heavily on filtered air for their comfort and wellbeing. To avoid triggering allergy symptoms, you should clean your filter whenever it is visibly dirty, or you notice an increase in your allergy symptoms at home. 
  • You’re doing some renovations. Renovations tend to create more mess than usual and can create drywall dust and other airborne particulates. If you are doing any renovations that could compromise your home’s air quality, you should keep an eye on your furnace filter and be prepared to change it more frequently than usual until the renovations are complete. 
  • You often leave your windows or doors open. In the warmer months, many Ontarians leave their windows and doors open to help cool their homes. However, letting that relaxing summer breeze also brings in dust, dirt, and other airborne particles that your furnace needs to filter out.
  • Your house gets very dusty. Depending on your location, you may find your home gets dusty fairly quickly. If this is the case, you’ll need to replace your furnace filter more often than the guidelines suggest to continue to enjoy good air quality. If you find that your house has been dustier than usual, it may simply be that your furnace filter needs to be changed.

Every home and every family is a little bit different, which can affect how often you need to be changing your furnace filter. That’s why the best way to ensure your furnace filter stays clean is to check it regularly and swap it out or clean it as often as necessary. 

Replacing your furnace filter as necessary is a great way to increase your home’s air quality, reduce the amount of work your furnace needs to do, and reduce your heating bill.