Are Washable AC Filters Good for Your HVAC?

Nolan is a home home handyman who has installed several types of washable filters in home HVAC units for his customers.

A washable, reusable HVAC filter.

What Are Washable AC Filters and How Do They Work?

Washable, reusable AC filters are an alternative to pleated disposable paper HVAC filters. They typically cost more than disposable paper filters, however, they’re designed to be used multiple times, saving money in the long run.

How They Work

Reusable AC filters may use either fibrous layers combined with an electrostatic material to attract and catch dust particles, or may use a porous synthetic material that works similar to disposable paper filters, allowing air to flow through but holding back larger dust particles.

K&N washable HVAC filters, which we tested for this article, use the latter kind of filter media.

Note: HVAC stands for Heating, Ventilation and Air Conditioning and AC stands for Air Conditioning. For the purpose of this article, we’ll use these acronyms interchangeably.

Stay away from non-pleated washable filters, as these can reduce air flow to your HVAC unit, reducing efficiency and even causing damage in some cases.

Pleated vs. Non-Pleated Reusable HVAC Filters

There are two main types of washable HVAC filters: pleated and non-pleated. The first type of washable HVAC filter we purchase was non-pleated, as seen in the photo above.

After testing our reusable filter against a disposable paper filter, using a handheld CFM meter (placed directly in front of our registers), we found a reduction of approximately 20% in airflow when the non-pleated washable filter was installed.

After this disappointing airflow test, we sent it back for a refund and purchased another brand of washable filter, one with a pleated surface instead.

For years we’ve been fans of K&N filter products, since we’ve used their automotive air filters in our vehicles with good success. We chose this brand because the filter surface is pleated, which provides more surface area than reusable AC filters that only have a flat surface.

Once the surface of a flat, non-pleated reusable AC filter becomes clogged with dust, it may cause a reduction in airflow to your HVAC unit. Reduced airflow may severely impact your unit’s efficiency and can even cause damage to the system in some cases.

Testing the K&N vs. Disposable Filtrete and Reusable Off-Brand Filters

Using a handheld wind speed monitor, we measured the K&N against our Filtrete paper HVAC filter and found almost no measurable difference in airflow. We repeated the test several times, and in some cases the K&N offered slightly better airflow (2%) than the Filtrete Allergen Defense disposable.

Our off-brand reusable filter showed a 20% reduction in airflow when compared to both the Filtrete disposable and K&N reusable filters.

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Methodology: Using a BTMETER BT-100 handheld anemometer—mounted on a tripod—we measured the air speed coming out of the register closest to the air handler with each type of filter: pleated paper disposable, flat fiber reusable and pleated K&N reusable. We wrote down the difference in air speed readings, subtracted the numbers and used this factor to determine a percentage difference between filters.

Ordinarily you should not let your washable HVAC filter get this dirty since it will negatively impact air flow.

Ordinarily you should not let your washable HVAC filter get this dirty since it will negatively impact air flow.

How Much Money Do Washable, Reusable AC Filters Save?

Not all home HVAC filters are the same size, and not all systems use the same number of filters, but for the sake of our example, we’ll look at the costs of each type of filter for an AC unit that uses just one filter.

Our Experience Saving Money With Reusable AC Filters

For our own Carrier home HVAC unit we purchased one 14x25x1 inch K&N Washable AC filter, which cost $40. We have indoor pets and our home is near an active rock quarry, so we often get lots of indoor dust. Under normal circumstances we change our HVAC filter every two months.

How Much Money Do Reusable AC Filters Save?

Before switching to the K&N filter we regularly purchased Filtrete Allergen Defense filters, at a cost of $34 for a pack of two. Our cost for paper filters each year was around $102, compared to the initial price of $40 for a washable filter, which should last a lifetime according to the manufacturer. The amount we’re saving by switching to a K&N washable AC filter should amount to approximately $62 each year.

Your savings will vary, depending on which reusable filter you purchase, how many filters your HVAC uses, what size they are, and most importantly, how often you change your filter out.

14x25x1 K&N AC Filter vs. Filtrete Allergen Defense Disposable

  • 3 Month Interval Cost Savings of K&N Filter vs. Disposable: $28 per year
  • 2 Month Interval Cost Savings of K&N Filter vs. Disposable: $62 per year
  • 1 Month Interval Cost Savings of K&N Filter vs. Disposable: $164 per year


MERV Rating: What Is It?

MERV stands for Minimum Efficiency Rating Value. This standard was developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers to report a filter’s ability to capture larger particles between 0.3 and 10 microns. The higher the MERV rating, the more dust particles the filter removes from the air entering your HVAC.

For example, both our old Filtrete Allergen Defense filter and our new K&N washable HVAC filter have a MERV rating of 11, meaning they remove 85% or more of particles between 0.3 to 10 microns in size. This is considered to be in the range of “better” home air filters, compared to “economy” disposable filters which have a MERV rating of 5 to 7.

Beware of Cheap, Washable HVAC Filters

Many cheap washable HVAC filters don’t list their MERV rating. Be wary of any reusable filters that don’t list this important rating number. Also, stay away from washable filters with a MERV rating under 7, which is too low to keep dust from accumulating in your home and inside hearing and cooling ducts.

The higher the MERV rating, the more dust particles that are are removed, however there comes a point at which the tradeoff for higher filtration may be reduced air flow.

The Bottom Line

Pros and Cons of Reusable HVAC Filters

  • Higher upfront cost
  • Slightly less convenient than disposable paper filters
  • Better for the environment (less waste)
  • Save money over the long run
  • May offer better or worse filtration than disposable—depending on brand

We’re very happy with our K&N washable AC filter. It’s already saved us money and we expect it to last a lifetime. We also love the fact that we’re not sending all that waste to the landfill!

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This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2022 Nolen Hart