When there is less daylight, and the temperatures start to fall, it can only mean one thing – it's time to look at your furnace! Having a well-functioning furnace ensures that homes stay warm and cozy no matter the weather.


Your furnace moves air throughout your home at a designated temperature, and during the late fall and winter, it will probably be constantly working. To make sure that your air flow is as efficient as possible, you should check that your furnace filter is in peak shape.

Why Change Your Filter?

At first glance, a furnace filter looks like a thin rectangle – how much work can it do? A lot, actually. That rectangle can play a huge part in the how well your furnace operates and in the quality of your indoor air.


When your furnace runs, the filter will collect certain airborne particles, such as dust, that you would otherwise breathe in. But after time, too much debris will clog up the filter, making it difficult for air to pass through. This causes your furnace to work much harder to heat your home, resulting in higher energy costs – and poorer quality air.


How Often Should You Change Your Furnace Filter?

A basic rule of thumb is to change your furnace every three months. Doing this gives enough time for debris to collect to require a new filter, but still prevents an overworked furnace. But that is just a guideline. Other factors that affect the state of your furnace filter include the following:


  • Pets: Having pets, especially multiple animals or long-haired breeds, will generate pet dander, requiring you to change your filter more often.
  • Smoking: If someone in your home smokes or you have frequent visitors who smoke indoors, you will need to replace your filter more than every three months.
  • Construction zone: If you have recently renovated your home, live in a subdivision under construction, or have someone in the home who enjoys woodworking, dust would collect more quickly, requiring more frequent filter changes.
  • Type of filter: The type of filter you use can also dictate the frequency of filter replacement. Furnace filters are rated using a Minimum Efficiency Reporting Value (MERV). The higher the rating, the more particles the filter can remove from the air, but that also means the more frequently you need to replace the filter.


Every home is different, and everyone has different lifestyles that can affect the state of your filter. The best way to know when you should change your air filter is by checking it regularly.


Don't let a dirty furnace filter harm your indoor air quality – change your filter often, and breathe in fresh, clean air all year round.

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Mr Furnace Heating and Air Conditioning
28 Dunkirk Road St. Catharines, ON L2R 1A1, Canada
Phone: 905-390-1726

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