A critical part of keeping your A/C running smoothly is ensuring you have the right filter. But with so many different types and brands of filters on the market, how do you know which one is right for you?
Before you know what kind of filter to buy, it’s important to understand the basics of how an air filter works and cover some of the most common questions:
What’s a MERV rating?
You’ll usually see the quality of air filters rated in terms of a MERV scale. This stands for “Minimum Efficiency Reporting Value.” The word “minimum” means here, what would be this filter’s minimum/worst performance when dealing with tiny micro-particles? The higher the MERV rating, the higher this worst-case performance, and the better the best-case performance! We essentially measure how effectively a filter can remove particles from the air:
A MERV rating of 1 to 4, for example, means that only larger particles such as pollen, dust bunnies, insect parts, and carpet fibers are being filtered out. A MERV rating of 5 to 8 will get rid of smaller particles like mold spores and pet dander. A MERV rating of 9 to 12 means that the filter removes large bacteria particles from the air. While a MERV 13 to 16 filter will remove most tobacco smoke, chemicals, bacteria, and larger viruses!
What’s a HEPA filter?
MERV 13 to 20 filters are used in hospitals and other commercial buildings where the very highest level of filtration is desired. The best filters (MERV 17 and above) are called HEPA filters, which stands for “High-Efficiency Particulate Air.”
But is it always the right decision to get a HEPA filter for your home? Not necessarily, depending on the capacity of your air conditioning system. A HEPA filter may be fine if you have a new A/C or heat pump. But if you have an old unit, then using a HEPA filter may cause your unit to work too hard and use more energy than necessary because it is harder to push air through such a thick filter.
What’s the difference between a pleated filter and a fiberglass filter?
Pleated filters are made of multiple layers of fabric that are pleated (or folded) to create a larger surface area. This allows the filter to trap more particles and last longer than a traditional fiberglass filter. Fiberglass filters are made of a mat of fiberglass fibers woven together. These filters are less expensive than pleated filters, but they need to be replaced more often because they can only trap so many particles before they become clogged.
What are those numbers on the side of the filter?
Air filters are also given a size, usually in inches. This is the size of the filter you’ll need to buy for your A/C unit. The size is usually written like “16x20x1” or “20x20x1”. In this example, the first number is the width of the filter, the second number is the height, and the last number is the depth. Make sure that you pay close attention to the size of the filter and don’t buy the wrong one that won’t fit!
Is there anything else I should know?
Now that you know a little more about filters, is there anything better? Yup, and according to Ken Elowe, “upgrading from a standard filter to an electronic air cleaner will distribute cleaner air to every room in your home because electronic air cleaners trap and filter up to 99% of airborne particles that pass through your HVAC system.”