Your Guide to HVAC Filters

Indoor air quality can be improved significantly by replacing HVAC filters. Do you know what type of filter is best for your HVAC system? Read to find out!

Understanding Different Types of HVAC Filters

Usually, HVAC filters come in standard sizes that match most residential and commercial HVAC units.

Before you order any new replacement HVAC filters, double-check the size you need. Usually, you can find the dimensions on the box or manual from the manufacturer. If you need to, get a ruler out and check the old-fashioned way!

Otherwise, contact Sig Cox Heating & Air Conditioning and we can help you determine what you need.

HVAC Filters for Your System

There are many different kinds of air filters. Depending on the minimum efficiency reporting value (MERV) rating, they can range anywhere from $2 to over $100.

You’ll need a custom-sized filter if you have an unusually large or small HVAC unit. Most manufacturers only make standard sizes, though some will create custom ones at higher prices.

Essentially, every building has a unique layout, meaning you can expect all kinds of oddly shaped filters across the market.

How Do HVAC Filters Work?

HVAC filters are sheets of foam and special perforated paper that work by trapping microscopic dust particles. Normally, you slide an HVAC filter under a slot below the furnace unit inside what’s known as the return grille. Your filter serves to keep your system clean by preventing particles from polluting the indoors atmosphere.

However, most filters just block the dust and bacteria, they don’t destroy them. Over time, the screens will become clogged and become hazards themselves by building up an overload of particles.

What Are Standard HVAC Filter Sizes?

While they might vary by the manufacturer, most filters in the industry come in set dimensions measured by inches, including:

  • 10 x 20
  • 12 x 12
  • 12 x 20
  • 12 x 24
  • 12 x 30
  • 12 x 36
  • 14 x 20
  • 14 x 24
  • 14 x 25
  • 14 x 30
  • 15 x 20
  • 16 x 20
  • 16 x 25
  • 18 x 18
  • 18 x 20
  • 18 x 25
  • 18 x 30
  • 20 x 20
  • 20 x 24
  • 20 x 25
  • 20 x 30
  • 24 x 24
  • 25 x 25

What Happens When You Have a Dirty Air Filter?

When a filter is clogged with dirt, it can lower the effectiveness of your system and increase your heating and cooling bill each month. Eventually, the dust will begin to collect on the coils deep within the HVAC system. It’s much more expensive to clean or replace the coils instead of just changing the filter.

Depending on the size of your building, how many people reside in it, and the filter type, you should change your filter every one to three months. Use good judgment and check for clear signs of buildup on the filter.

Scheduling regular HVAC maintenance can also help ensure your air filter is the correct size, clean, and helping your system work effectively.

Need HVAC maintenance or filters in the North Augusta area? Contact Sig Cox today!

What Are the Different Types of HVAC Filters?

There are several types of HVAC filters on the market. Which one you choose for your home is largely dependent on your system and you and your family’s needs. Those who suffer from severe allergies will want to spend a little extra on higher-quality filters, for example.

The amount of purification you want and the quality of air in your home all depends on the type of HVAC filter that you have. Let’s take a look at the various filter types out there.

There are four main types of HVAC air filters—fiberglass, pleated/polyester, electrostatic washable, and HEPA.

1. Fiberglass HVAC Filters

Fiberglass is a term used to describe threaded man-made glass material. For HVAC filters, it’s the cheapest material and has the shortest life span compared to others. They are often called “disposable” filters because experts recommend you trash them after a month.

They are most effective at blocking larger particles, like bugs and dust mites. However, they aren’t very durable. Even with a reinforced metal frame, they won’t last longer than 30 days. Most HVAC filters that you see are made out of fiberglass. Individual strands of fiberglass are spun together to catch particulates that are brought in with the outside air.

Only large particles will be filtered by this type of filter. They will not help keep your home free of smaller airborne matter. These filters are inexpensive, usually anywhere from $2-$10 each, and they can be thrown away without having to think twice about it. For this reason, they will likely continue to be the most common air filter used.

2. Pleated or Polyester

cheap air filters

Pleated/polyester filters are similar to fiberglass ones. However, they have an added wired back for increased durability and ability to capture even smaller particles. Typically, they last up to 90 days. Pleated HVAC air filters cost more than fiberglass HVAC filters, but they are still fairly inexpensive.

So, while they might cost more than their fiberglass counterparts, you’ll save more annually by using them. For an additional level of filtration, some people opt to use pleated air filters. These types of filters are often made out of polyester or similar material. They can eliminate additional particles such as pet dander, dust mites, and other medium-sized particles.

You can remove around 45% of particles from your home’s air with this type of filter. You have the choice of buying reusable or disposable pleated HVAC filters. The reusable ones can just be washed and dried, then put back into the system. Just like with fiberglass HVAC filters, the disposable pleated filters can be thrown out in the trash.

3. Electrostatic Washable

popular air filters

These rely on static electricity to collect the dust, rather than filtered cloth or foam. It’s a relatively expensive option, usually around $30 to $100. 

It’s considered permanent since all you need to do is wash it once a month, rather than replace the whole thing.

Cotton and paper are typically used to make this filter, and there are even disposal electrostatic filters available.

air filters that are washable


HEPA stands for high-efficiency particulate air. HEPA filters are capable of removing the most air particles and are the most efficient commercially available type of filter on the market. With the ability to block and eliminate 99.97% of particles down to 0.3 microns in size, they will guarantee you the cleanest indoor air possible.

These are commonly used in powerful air purifiers for offices, medical labs, and in disaster recovery. They will leave your home free of a variety of contaminants. That includes tobacco smoke and tree pollen. Air is forced through the filter, which is made of aluminum and fibers, and the contaminants are removed during this process.

These are the most expensive of air filters out there, as most quality HEPA filters are over $100. HEPA filters can also be cleaned and reused.

allergy air filters

Where Do You Find Custom Filters?

If none of the above sizes match perfectly, you’ll want to order a custom-made filter to fit your system.

If you attempt to use a filter in the slot that is too small, air will just flow around it and render it useless. On the other hand, if you try to jam in a filter that’s too large, the edges will become crushed in the tight space, and it won’t last very long.

There are plenty of companies that sell air filters of different sizes and materials, both offline and online. There are even companies out there that can design, engineer, and manufacture custom air filters according to your specifications.

You might want to explore companies such as Precision Filtration ProductsFiltertech, or Koch Filter Corporation.

However, you should know that custom filters tend to cost more and may take 5-10 days to manufacture.

Before you commit to investing in a custom air filter, give Sig Cox a call at (706) 722-5304. We can give you the exact measurements you’ll need and recommend the right brand.

HVAC Filters & Maintenance in North Augusta, SC

HVAC filters are the cornerstone of your air handling system, whether it is for your home or business. There are many options so you can get the level of clean air that you need.

Sig Cox Heating & Air Conditioning is here to serve you for all your heating, cooling, and air quality needs. From simple fixes to new installations, we cover it all! We’re open 24/7 to handle any residential or commercial job.

Call us today for a free quote on your needs (706) 722-5304 or contact us online.

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Customer Reviews

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“I called 6 other companies when my AC stopped pushing air at 5PM. None of them seemed to want my business. When I got to Sig Cox, the guy who answered the phone was polite, knowledgeable, and was even trouble shooting with me before sending someone out. The agent got to my house in 30 minutes, troubleshoot, and fixed the problem in another 30. He even topped off the freon for free. The pricing was definitely agreeable. You’d get charged the same or more with any other company. Some of the best customer service I have seen. You should absolutely consider Sig Cox for you HVAC problems, I won’t be looking anywhere else.”
Nicholas Brennan
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“These people are amazing. After hiring Sig Cox the first time to fix my HVAC unit about a year ago, I was more than happy, to say the least. Then about a week ago I had them install a new HVAC unit for me. This is by far the best a/c repair company in Augusta GA. They are professional, timely, and really take care of their customers. I highly recommend them and proudly give them an A+ rating! Thank you all so much!”
Chris Kirksey
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“This company did some work for my mother-in-law, of which she was quite pleased, so she recommended them to us. We had a downstairs unit that just wasn’t putting out any cool air. They came by post haste and assessed the unit, gratis. Of course it was a compressor failure so we had to make the hard decision to buy a new unit or fix what we had. The advice we got from our man on the scene was honest and sincere.
Since we had an older unit that used the phased out Freon and compressors are ugh, expensive, we went with a new unit. We decided on the Amana since it had a lifetime warranty on the compressor and rated well in Consumer Reports.
A month later the other unit failed and we replaced that as well. Six Cog worked with us on the price, we were never hassled on the payment, nor did they demand any payment on the spot and never did I feel pressured into anything. The install was smooth, fast and highly professional. Both units fired up, granted a month apart, and the house was cool almost immediately.
This company has a great reputation from what I can garner in the community, and I’m here to tell you that I recommend them highly as well. Please note that this is first recommendation I have ever put online.”
Donald Bradshaw
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“Very good experience. The Service Technician, David, went above and beyond to assist us in our AC repair.”
Daniel Brown
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“From the first time that Mr. Boarwright came out, I knew that your company was top of the line. None [of the other companies] laid it out on paper like Sig Cox.”
Steven Burris
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“Thank you and your crew for your profession assistance in solving our unique heating and cooling situation that involved two seperate zones.”
PJ Rodgers
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Margaret Brubaker
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My air conditiong system went out, Sig Cox was recommended so I called them. Technician Andrew came out, was on time, and he properly diagnosed the problem. He had the part ordered. When the part came in, Nolan installed the part perfectly. Both technicians were very professional and knowledgeable. I even talked to the owner of the company who is involve day-to-day with his company. Very nice people to deal and they really go beyond what’s expected to help you get things fixed. I highly recommend Sig Cox!! Ask for Andrew or Nolan, they know what they’re doing!!
Dan Can
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“We had a heating and air company we were satisfied with, but when we needed a new unit we went with Sig Cox because of the deal we couldn’t beat. We have been SO impressed with everyone we have worked with, from the customer service, to the salesman, to the technicians, they are all so friendly and professional! We will be loyal customers from now on!”
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