You know you need to change your furnace filters; you keep reading about how important it is. But you cannot seem to get a good answer on how often you should be changing them. There is no specific rule for how often they should be changed. However, there are some general guidelines and things to look for to ensure you change them often enough.

General Rule of Thumb

Many furnaces use either 1-inch or 2-inch filters. If these are the kind of filters you use, plan to replace them at least every 30 to 90 days. Where you fall in this range depends on the kind of filter you use, covered below.

If you have larger 3-inch or 4-inch filters, you should plan on every six to nine months. And if you have the largest 5-in or 6-inch filters, plan for every nine to 12 months. These are just the general rule of thumb. How often you really need to change the filters will depend on the kind of filter you use and the air quality in your home.

Difference in Filters

Not all air filters are the same. Rather, they can be made from different materials, have different weaves in the filtering medium, and other features that change how they work. Basic filters have a fiberglass medium and are usually either white or blue. These are effective but do not provide the best filtering. However, your furnace may be able to get enough airflow with better filters.

Then you have the pleated fiberglass filters. The pleated design is more efficient at capturing particles from the air passing through it.

Then you have the rating of the filter, which varies by manufacturer. The higher the rating, the smaller the particle it pulls out of the air. This can also mean that you will have to change your filter more often.

Differences in Air Quality

Your air quality plays a significant role in how long your filters last. One of the primary measures of air quality is the amount of particulates circulating in the air.

The humidity in the air can affect how many particulates are circulating. The EPA recommends maintaining a humidity level of between 30% and 50%. If your air is dryer, then the particulates become light enough to stay in the air, leaving more work for your air filter.

Home projects can also affect your air quality. If you are cutting something that creates a lot of dust, or mudding and sanding, this will add more particulates to your air. You will want to check your filters about a week after completing these projects to ensure they are still clean.

Signs of Airflow Restrictions

Your system works off the simple premise of circulating air around your home. When your filters get clogged, it inhibits the air from circulating properly. There are signs your system is struggling to circulate air, which could be linked to your air filters. If you experience any of these signs, consider installing new filters:

  • Increasing energy bills
  • Less air coming from your vents
  • Short cycling
  • Longer cycles

Noticing More Dust

Keep an eye open for accumulating dust around your home as well. As your filters begin to clog, they become less effective at removing the dust from the air because they pass less through.

If you notice more dust than usual, be sure to check your filters. Also, keep an eye on your air vents for dust collecting around them. This is a sign that your filters are not functioning optimally.

You Keep Getting Sick

One of the beauties of air filters is the health benefits they offer. Some filters will remove particles so small, they will actually catch viruses.

Many people will experience respiratory irritation when their air quality decreases. This irritation can lead to both sinus and respiratory infections. If you notice you have recurring illnesses, then you may have a problem with your air filters. Check to make sure they are passing air properly and are not overly clogged.

Kahn Air Conditioning has been serving the Northridge, CA, area for more than 60 years. Our team brings expert air conditioning, heating, air quality, and energy management solutions to each of our clients. Call to schedule your HVAC consultation today.

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