furnace filter calgary

Finding the Right Furnace Filter

When you walk into the furnace filter aisle in a hardware store, it can be overwhelming to look at all the options available. From the size of the filter and impurities you want to remove, to the price and name brand, there are a lot of things to consider before you head to the check-out aisle. We asked the experts to weigh in on furnace filter selection, and here’s what they had to say.

Size of the filter matters

Yes, different furnaces require different filter sizes, so it’s important that you select the right size for your furnace. Furnace filters are sized by width, length, and thickness. The easiest way to tell is to check the dimensions on the filter that is currently in the furnace before you go shopping.

Alternatively, the owner’s manual for your furnace should tell you what size you need. If you can’t find the manual, you can always google your make and model.

Read the ratings

Different filters have what’s called a “microparticle rating”. The higher the rating number, the smaller particles can be removed from the air. A basic filter will be a 300 microparticle rating and will remove dust and lint. A midrange filter, at 600 microparticles, will also capture dust mite debris and mold spores. Allergy-rated filters (rated around 1,000 microparticles) will help with pet dander, pollen, and smoke. And the high-end filters, at 1,500 microparticles, can remove bacteria viruses and odors, and maximize the air quality. Naturally, the price goes up when the rating does.

You may be surprised to learn that many professional furnace cleaning companies will recommend a basic filter for most furnaces, as long as it is replaced on a monthly basis!

The reason is that thicker filters with higher ratings tend to clog more quickly, making the furnace work harder, causing a reduction in efficiency and prematurely wearing out parts. The good news is that basic Fibreglass type filters are available at a fraction of the cost, come in bulk quantities and there are several non-brand name options, so it can actually be cheaper to use these filters even with the increased replacement frequency.

It is worth considering higher-end filters if you have allergies, pets, or an older home with mold or mildew issues.

Out with the old

When it comes to keeping your furnace running optimally and your air clean, regular filter replacement is essential. Changing your filter helps keep your system working more efficiently and for longer. And a more effective system means less need for furnace repairs or furnace replacement. Basic filters should be changed monthly. Many of the higher-end filters recommend changing every 90 days. If you have pets, a dusty environment, or have just had renovation work done, check your filter more frequently.

Some other signs that it is time to change your filter include:

  • Energy bills creeping up
  • Increased sickness or allergy symptoms
  • More dust in the air (or collecting on countertops, floor, and furniture)
  • It takes longer to heat your home (due to the short cycling furnace)
  • When in doubt, it’s good to replace the filter

Spend wisely

A top-end filter can cost as much as $50/filter. It will last longer, and also provide better filtration. But as we mentioned, for most homes, a basic filter will do just fine. In most cases, you can save money by purchasing a pack of 3 filters versus buying a single filter.

Generic is okay

While there are several different sizes and ratings, there are a number of different brands available on the market. And while you may be sucked in by a brand, what really matters in the end, is the performance, not the logo.

To read more about furnaces in our Homeowner’s Furnace Guide, click here.


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