Pleated Filters or Fiberglass Filters: Which is Better?


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Pleated and fiberglass air filters are the two most common options for in-home HVAC systems. They’re practical, affordable, and efficient. Some people prefer fiberglass filters because of their low cost. Others prefer the pleated filters due to their ability to capture microscopic allergens from the air.

Pleated air filters provide better indoor air quality and are made in a variety of MERV ratings from 5 to 13. Pleated air filters have more surface area allowing it to capture more airborne pollutants and allergens such as pollen, pet dander, and mold spores. Pleated filters are stronger and can last up to 90 days, 3 times longer than fiberglass filters.

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Fiberglass air filters are not as strong as pleated filters. The cardboard frames in fiberglass filters bend easily which can cause the filter to collapse onto itself. Fiberglass filters also provide little protection against small airborne particles. The material is not tightly woven which can’t capture microscopic particles. Fiberglass filters need to be replaced every 30 days.

Throughout this article, you’ll learn all sorts of useful information, including:

  • Why pleated filters are so much better than fiberglass filters
  • Which MERV ratings you should choose
  • Whether or not pleated filters restrict airflow

Why Are Air Filters Pleated?

Pleated air filters are folded into an accordion fashion to allow for increased surface area to capture more airborne particles. The pleated design creates virtually double the surface area of traditional fiberglass non-pleated air filters.

This actually improves airflow as the ridges of the pleats help to distribute air more evenly than non-pleated filters. This means your heating and cooling system doesn’t have to work as hard thus increasing longevity.

Do Pleated Air Filters Restrict Airflow?

Pleated air filters are much more sought-after because they catch far more pollutants. Various particles floating through the air are caught in the weave of a pleated filter that would pass right through ordinary fiberglass air filters. The downside to this efficiency is that it can quickly lead to restricted airflow.

When the airflow is reduced, your energy bill climbs up, and dust eventually causes a serious blockage, starving your system of necessary airflow. The proper air filter maintenance will keep your airflow as it should be without risking damage to the internal coils.

If the internal coils get dirty, that dirt mixes with the condensation produced forming a slug that can clog your condensate drain pipe. A clogged drain pipe can cause major problems to your heating and cooling systems as well as interior water damage.

Pleated air filters can reduce or even eliminate the need to have your air ducts cleaned. See our article Should You Clean Your Air Ducts? Separating Fact and Fiction for more information on cleaning air ducts and how to prevent the need from arising at all.

  • Clean and replace your air filter regularly. Most are filters are disposable. This includes both fiberglass and pleated air filters. Fiberglass air filters should be replaced every 30 days. US Home Filter states that you should replace pleated air filters once every 90 days to prevent the dust from building up. However, your pleated filters may need to be changed sooner if you have several in-home fur babies.
  • Choose the correct MERV rating. A MERV rating is a system based around the efficiency of a filter. The higher the number, the denser it is. High-density MERV filters catch tons of dust, but they can get clogged easier. In the next section, you’ll be able to figure out which MERV rating is meant for your home.
  • Get the right size filter. Aside from the rating above, you also need the correct dimensions of a pleated filter. Anything too big will become bent, limiting the effectiveness of the filter. On the other hand, a filter too small will allow dust particles to pass around the filter without resistance.
  • Don’t clean disposable filters. Some homeowners get a bit too tempted to reuse their air filters by attempting to clean them with bleach and other chemicals to wash the debris away. Unfortunately, this will damage the fibers and make the cardboard frame very weak. This will likely only rip the filter apart. Reusing washed air filters can cause the fibers to get clumped, cause dust to build up, and thus restricting the airflow much quicker.
  • Inspect the pleated filter after a windy day or a storm. When wind moves particles through the air, your filter is forced to work extra hard. Sand, dust, dirt, and other debris can clog your filter quickly. You might not have to replace it, but giving it a shake-off will keep it going as it should.

What MERV Rating Should I Buy?

As you probably read above, the MERV rating of your filter will determine how well it works. Hospitals and nuclear power plants have incredibly high MERV ratings, reaching upwards of 15 to 20. These ratings would be virtually useless in your home. In fact, they’d be worse than having no filter at all.

It’s important to remember that there’s a limit to MERV ratings before air can’t flow through it properly. In-home pleated air filters should have a rating between 5 to 13. If you live in a windy region with lots of dirt and dust, then aim for the higher end of the scale. If you’re fortunate enough to have low humidity, low wind, and not too many pollutants, then 5 to 8 will work fine.

Second Nature shows us that getting the incorrect MERV rating can be harmful to our air circulation systems. When a filter is too compact and dense, it prevents air from flowing through regularly. For example, getting a pleated filter with a MERV rating of 18 would stop potential viruses from flowing through, much less dust and other debris.

The goal is to have dust trapped, but when it gets too high, dust will clog the filter in a matter of minutes. Since you’re trying to stretch it up to 3 to 6 months at a time, you can see how the expenses can add up quickly.

On the flip side, low MERV ratings become ineffective. When dust can flow freely, it’s almost pointless to have a filter at all. Anything below a five won’t be useful enough to purchase.

You’d think that companies would only produce air filters with the necessary MERV ratings, but you’d be wrong. Many brands try to push low-cost filters without labeling a MERV rating. You’ll end up getting a great price while having a filter that’s barely efficient enough to sort out coffee grounds, much less dust.

Why Are Pleated Filters Better Than Fiberglass?

As mentioned in the introduction, pleated filters are much better than fiberglass filters. If you’re still on the fence between the two options, the let’s examine five reasons that this statement holds true:

  1. Pleated filters last much longer than fiberglass filters. They’re built to hold together for extended periods of time, overshadowing the value and efficiency of any fiberglass filter on the market. Not only that, but they can withstand more dust and other particles before needing to be replaced.
  2. Pleated filters are made with higher quality standards than fiberglass filters. Most fiberglass filters are good enough for houses, but they’re some of the lowest quality filters around. Pleated filters have densely woven fabric that doesn’t loosen from excess pressure or airflow.
  3. Another reason that you might want to choose pleated air filters is that they come in a variety of MERV ratings. Rather than being stuck with unmarked or low-rated fiberglass filters, you can choose anything between 5 to 13 on the scale. Note that most pleated air filters have a MERV rating of 8.
  4. Fiberglass is messy to deal with and itchy on the skin. If you’ve ever worked with fiberglass, then you know how bad it can be when it starts to get on your arms and face. You’ll need to wear protective clothing when you’re cleaning or replacing the filter. There’s also a small risk of sending fiberglass throughout your home.
  5. Finally, many houses and apartments require pleated filters. You don’t even have the option to choose fiberglass, which makes them not worthy of buying in the first place. All of the aforementioned benefits are in favor of pleated air filters, so most landlords refuse the use of fiberglass.

The pros of pleated filters far outweigh the cons. As long as you clean and replace them on schedule (see manufacturer recommendations), you shouldn’t have a problem with restricted airflow.

Pleated air filters are designed to be installed in the direction of the airflow. Improper installation can restrict airflow and cause the filter to fail prematurely. See What Happens If My Return Air Filter Is Installed Wrong for more details and to determine if your air filter is installed correctly.

To the same point, running your heating and cooling system without an air filter can damage the internal coils.

Conclusion

Pleated filters are better than fiberglass air filters, without a doubt. Perhaps the best news of all is that you don’t have to spend too much more money on them than you would on a fiberglass filter. They also last much longer, so you’ll end up saving your hard-earned money in the long run.

Here are what you should have learned from this post:

  • Choose a MERV rating between 5 to 13.
  • Pleated filters are much more efficient than fiberglass filters.
  • Fiberglass can be ineffective and potentially dangerous.
  • If they’re not cleaned or replaced, pleated air filters can restrict airflow in your home.

Sources

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Hubert Miles

I've been conducting home inspections for 17 years. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and FHA 203k Consultant. I started HomeInspectionInsider.com to help people better understand the home inspection process and answer questions about homeownership and home maintenance.

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