How Often Should You Change Your Home HVAC Filters?

In general, most air filters and HVAC companies recommend changing your filter every 90 days or 3 months. This may vary depending on the location of your home, if you have pets, and the age of your system and equipment. The ideal is to change your air filter every three months, however, there are certain factors to consider when determining when to replace an old filter. Depending on your lifestyle and the type of air filter you choose, you may want to change it more often.

A number of factors need to be taken into account when deciding how often a furnace filter should be changed, and many filter manufacturers suggest how often their product should be replaced. As a general rule of thumb for pleated air filters, such as those manufactured by FilterBuy, it is recommended to replace the filter every 90 days. As the filter accumulates more dirt, dust, and allergens from the air, its efficiency decreases. Find out below if you should replace the filter more often.

We will explore each of these factors. This is by far the most important factor. The filter collects dust and debris only when the system is operating. The more it works, the faster the filter accumulates dirt.

During a cold Minnesota winter, a furnace filter will need to be changed more often than during a mild Missouri winter. On the other hand, you will need to change the filter more frequently during a hot and humid Missouri summer than during the Minnesota summer. Remember that a filter also gets dirty during AC mode. Do you find pet hair in your air filter? Hair fibers from dogs, cats, rabbits and other mammals are larger than dust and dirt that usually trap the filter.

This means they clog the filter and block airflow quickly. The more important clean air is, the more often the filter needs to be cleaned or changed. A coarse-media filter, MERV 11 or higher, or an electronic air filter is the best option when someone in the household has asthma, severe allergies, or difficulty breathing for any reason. The air will be cleaner than if a basic fiberglass air filter is used.

You may also want to consider an air cleaner for your system. Our Air Purifier Guide contains comprehensive information on all types of filters, including electronic and media air filters, how they work, which is best for your purpose, and more. Cheap fiberglass filters require less frequent replacement than pleated filters. Some sites get this exactly the other way around, claiming that thicker filters can last longer between changes. That goes against the design of the filters.

Coarse-media filters trap more and smaller dust particles, so they obviously clog up faster than slim fiberglass filters that don't trap as much dirt and debris. The good news is that some of those filters can be cleaned with a nylon brush and placed back in the oven or air controller instead of replacing them. Cleaning should be done outside or in a garage to keep dust and dirt out of your home. If removing dirt with a brush instead of replacing the media filter, be sure to change the filter after two or three cleanings. In the end, brush cleaning will not remove enough deeply embedded dirt and debris. In larger homes, more air flows through the filter than in smaller houses.

Because the air carries dust, pet hair, and other debris, the filter will get dirty more quickly in a system that serves a large house. Some of you wonder what we mean by continuous fan mode and why a homeowner would use it. There must be a setting in the thermostat such as Auto and Fan options. In automatic mode, the fan works only when the system is heating or conditioning the air in your home. In fan mode it works all the time until you turn it off.

The longer the system works even if it is not heating or cooling ,the faster the filter will get dirty and it will need to be changed. Is continuous fan mode a good idea? Here are its pros and cons: First it cleanses air by passing it through an air filter more often so it will need to be changed more frequently; second it helps balance temperatures in your home; third if you have a basement you can draw cool air from there to help cool upstairs rooms. Running fan requires electricity so you'll see an increase in your electricity bill; second basement air is usually more humid than upstairs so you'll need to lower thermostat settings to get rid of moisture; third bringing warm air from inside walls or attic to living spaces causes AC to work longer resulting in higher electricity costs. In summary we do not recommend continuous fan mode as standard operating procedure. This is real question isn't it? This question gets to heart of matter: Follow these steps to find out when to change your air filter: You may hear little wheezing even when filter is clean; it will worsen when dirty; know your system sounds it emits so you know what noises indicate problem; while these signs could mean problem with blower most likely dirty filter blocking flow of air; these hazards are easily avoided by checking regularly changing when necessary. One most important things you can do....

Doug Bundley
Doug Bundley

Professional coffee aficionado. General web specialist. Avid internet guru. Subtly charming beer nerd. Infuriatingly humble bacon specialist. Hardcore web evangelist.

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