January 20, 2021

A furnace’s filter is probably the least appreciated component of the equipment. It is also the easiest component to change, and changing it is one of the least expensive maintenance tasks. How often should you replace your filter, and is it the same for everyone?

Understanding How Your Furnace Works

Understanding how your furnace operates helps you understand the importance of your air filter and how often you should change it. In simple terms, a furnace does two jobs. First, your furnace circulates air. Second, it warms the air as it circulates through the system.

In order for your air to circulate, the system needs to be able to draw in the air easily. It then needs to be able to circulate the air back out into your home. If there are any airflow restrictions, your system will not work properly.

Why Changing Your Filter Is Important

When air first enters your furnace, it comes through an intake vent and through a furnace filter. This initial filter helps remove most contaminants from the air before it flows through the heat exchanger.

Unfiltered air allows contaminants to accumulate on sensitive areas like the heat exchanger and circulating fan. If the filter is doing its job effectively, it will prevent these buildups.

If not changed regularly, your filter will clog and create a restriction at the very beginning of the circulation cycle. This adds strain to the entire system, reducing its efficiency and leading to more repairs, both of which increase your operating expense. The additional strain also reduces the overall expected service life of your system.

Changing your filter is fast, easy, and relatively inexpensive compared to other repairs. You can see why it is so important to make this a regular part of your maintenance routine.

General Rules of Frequency

There are no specific hard-and-fast rules for how often you should change your furnace filter. You may see things around the internet recommending that you change it every 30, 60, or 90 days. You may also see that some filters are supposed to last six months or more.

The frequency is actually determined by what kind of filter you purchase and the size filter your system uses. Generally speaking, pleat-style filters are more effective and last a little longer than non-pleated filters.

Different furnaces need different size filters. Most gas furnaces use 1-inch or 2-inch filters. You will generally need to replace these every 30 to 90 days. If your unit uses 3-inch or 4-inch filters, you will need to replace them every four to six months. And if your unit uses 5-inch or 6-inch filters, plan to replace your filter every six to nine months.

These timeframes are just a guide and are greatly dependent on your air quality. The worse your air quality, the more often you should replace your filter. Also, keep an eye open for signs your filter needs replacing so you can do so before causing any damage.

Air Quality Considerations

Your air quality is an important factor in how long your furnace filter will last. Generally speaking, air quality measures how many contaminants are floating around in the air. These contaminants include particulate matter, volatile organic compounds, and biological pollutants.

Air quality is a variable thing within your home, so your filter life may vary depending on two important factors. Your humidity level will affect your air quality. The EPA recommends keeping your humidity between 30% and 50%. If your air is drier, it will cause more dust and particulates to stay airborne longer. More moisture than this encourages biological growth.

Also, the projects you do around your home can temporarily affect your air quality. If you are painting, sanding, or doing any woodwork, you are likely releasing more contaminants into the air. Plan to change your filter more often when you are doing these kinds of projects.

Signs You Might Need a New Filter

Given the variable nature of air quality, you should keep your eyes open for signs your filter may be clogging. These signs include:

  • Longer unit running cycles
  • Equipment that is short cycling
  • Cold air coming from your vents
  • Extra dust around your home
  • A dusty smell when your unit is cycling

Keep in mind that these signs may also be indicators of other problems. If you are experiencing any of them, check your furnace filter first. If you replace it and continue to experience these problems, call a certified technician to evaluate your system.

Premier Indoor Comfort Systems has been serving the Whittier, NC, area since 1999. Our NATE-certified team provides expert furnace and air conditioning installation, maintenance, and repair. Call us today to discuss your situation or schedule service.

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