Brought to you by the professionals at Southport Home Services

Welcome to the Filter Reference Guide provided by Southport Home Services. Our technicians and staff are happy to help you find the right air filter for your furnace. Contact us 24/7 for emergency furnace repair and check out our furnace air filter guide.

  • Which air filter will fit my furnace?
  • What are air filters made of?
  • How do air filters work?

  1. Which air filter will Fit my furnace?
  2. Having troubles figuring out which filter you need to buy to replace your current furnace filter? Southport Home Services is glad to help with that by providing this handy filter reference guide. There are a couple of aspects to filters that are important for you to know.

    The first aspect of your filter that is handy to know is the MERV rating. The acronym MERV stands for Minimum Efficiency Reporting Value. This rating system can help customers understand the efficiency of a filter before they spend any money on it. The MERV rating system ranges from numbers one to sixteen. The higher the MERV rating, the more efficient the filter is.

    • MERV 1: Least Efficient
    • MERV 8: Average Efficiency
    • MERV 16: Most Efficient

    The MERV rating may be more important to you for a few reasons. If you or someone in your family has bad asthma, investing more money into a filter with a higher MERV rating may be something you want to think about. The same goes for if someone in your household has bad allergies, a higher MERV rating can be helpful in that instance.

    The second aspect of your filter is measuring the length, width, and thickness of the current filter in your furnace. With this aspect, you have less room to play with, as there should be one size filter that will fit into your furnace. Once you measure your filter, make sure to write down the size of the filter for the future reference.

    Common Filter Sizes

    • 16x25x1
    • 20x20x1
    • 16x25x1
    • 20x20x1
    • 16x25x4
    • 20x25x4
    • 16x25x5
    • 20x20x5

    The final aspect to be careful of is how specific your filter is to your furnace. There are complex systems that require a filter designed specifically for that system in order to run properly. There may be times it is printed on the side of the filter to indicate so.

    If you are unsure and would like to be certain, give us a call here at Southport Home Services to set up an appointment for a Furnace Tune-Up and we can give you more information on your filter. Here atSouthport Home Services we also stock a large variety of filters and can track down odd sizes as well if you cannot find it yourself.

  3. What are air filters made of?
  4. Filters are made of different materials that affect the way that they perform, how long they last, and how much they cost. The main types are fiberglass, pleated polyester, washable/reusable, and High efficiency.

    Fiberglass filters usually are one of the cheapest filters you can buy on the market. They are designed to catch larger particles and typically have a lower MERV rating. Fiberglass filters also have a shorter lifespan, typically around one month. Fiberglass filters have less of an initial investment and will need to be replaced more often, but still will get the job done.

    Pleated polyester filters can be considered the next tier of materials used. The interesting fact about the polyester filters is that they are electrostatically charged. The polyester fibers in the filter are electrostatically charged in order to cling to and filter out more particles from the air. On average, a pleated polyester filter can last around three months.

    Washable/Reusable filters have been a popular choice of filter in the past. These filters are usually made of a plastic or aluminum and are usually designed with a MERV 8 rating. They can last anywhere between three to six years, depending on how well they are taken care of. The downfalls to washable/reusable filters are they usually do not go higher than MERV 8, they are quite pricey to purchase, and can be harder to find.

    High-efficiency filters are basically a standard pleated polyester filter but are thicker. A standard pleated polyester filter is around one inch thick and high-efficiency filters are usually in-between four to six inches thick. The increased thickness will increase the MERV rating and the life of the filter to around six to twelve months, depending on the household.

  5. How do air filters work?
  6. Let us start at the beginning of the process: what filters are taking out of the air. Inside your home there are a number of things that can affect your air quality. The big ones are dirt, dust, hair, pollen, and dandruff. Everyday life introduces these into the air inside your home. When you scratch your head hair and dandruff can be release into the air. When your kids run inside after a long day outside they will bring pollen, dust, and dirt along with them. Without a filter all of these air quality adversaries would be allowed to spread amongst your home and collected inside your ducts and furnace. Think of a furnace filter as a fruit strainer. The fruit is caught and kept inside of the strainer, while the water is allowed through into the sink. In this scenario, the fruit is the air quality adversaries and the water is the air flowing through your furnace. The abrasiveness, electrostatic charge, and the design structure of filters allow them to catch these particles out of the air. Do filters alone filter out viruses, microorganisms, smoking and cooking odors, cleaning supplies, etc.? In fact, all alone they do not. There are indoor air quality (IAQ) products that do combat all of the above.

To learn more about indoor air quality products check out our website today.

Another important side note is to remember to change your furnace filter regularly. How often it needs to be changed depends on a variety of variables. Look at our blog for our article on when to change your furnace filter. If you did not find what you were looking for or would like a professional to check it out, give us a call at 1-888-474-0277 or visit our website today!

Meet the Author
Thomas Suchla
Thomas Suchla


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