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November 27, 2023

In the realm of home maintenance, changing furnace filters is one of the easiest tasks you can tackle. When buying a furnace, this often-overlooked activity can:

  • have a huge impact on your home’s heating and air conditioning

  • help improve indoor air quality, and

  • it might even save you some money on both energy bills and HVAC system service.

That’s because a dirty filter can restrict air flow, cause loss of efficiency, impacting your furnace AFUE and maybe even impact the reliability of your furnace.

As you might imagine, just as there are a number of different types of furnaces on the market, like high efficiency furnaces, there are a number of options when it comes to furnace filters. Fiberglass filters, pleated filters, 1-inch filters and thicker 4-inch filters are just a few of the typical mechanical-type filters. More sophisticated electronic air cleaners and whole-home air purifiers have their own maintenance schedules, but many also include a pre-filter that needs to be replaced regularly.

For the health of you home comfort system, and to help improve the air quality within your home, it just makes sense to take a few minutes every month and inspect your system’s filter and if it’s dirty, go ahead and replace it.

The general rule-of-thumb answer to the question “How often should I change my furnace filter?” depends on the type of filter. For basic, 1-inch filters, the standard is every 30 days to 3 months. For thicker, pleated 4-filters, you can usually count on replacing them every 90 days or 6 months depending on the recommendations of the manufacturer.

Why is changing the air filter so important? Furnace filters are designed to both improve the quality of the air you breathe, and also to protect your HVAC system from build-up of dirt and debris. When you neglect your HVAC air filter, airborne pollutants such as dust, animal dander and pollen build up on its surface. Too much buildup can restrict airflow, making the air handler work harder. This not only affects the energy efficiency of your system; it can shorten the lifespan of your furnace which might cause you to ask “how long do furnaces last?” And, because your furnace blower is often an integral part of your central air conditioner, it can affect the longevity of your cooling system as well.

While replacing furnace filters on a timed schedule is important, it’s also a good idea to become familiar with some of the signs that your filter needs to be changed:

  • You notice more dust than usual, or faster build-up of dust after cleaning your home’s surfaces

  • It takes longer than normal for your system to heat or cool your home (longer heating / cooling cycles)

  • On visual inspection, the filter appears to be gray colored and / or you can see dusty, dirty buildup on the surface of the filter

  • If you can’t remember the last time you changed the filter, or if it has been in use longer than the recommended replacement time from the manufacturer – usually one to three months for basic 1-inch filters, or 3-6 months for thicker, pleated filters



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