Air filters work with a homeowner’s HVAC system to circulate clean air throughout the home via central ductwork. They oftentimes slide into a specialized compartment on, for instance, a furnace. Once the air is called for, the furnace pushes it through the duct where the filter is located, so any allergens and bacteria are prevented from passing. To experience the best air filtration in your residence, many manufacturers suggest replacing your air filter anywhere from every 6 months to every year.
There are several types of filters: spun glass filters, pleated filters, HEPA filters, and washable filters. Spun glass filters will be the most inexpensive, but they should also be changed more often. Pleated filters assist in filtration, as the air has to go through more to get through the material. HEPA filters are expensive, but they capture 99.97% of particles. Washable filters, well, it’s in the name! A homeowner can clean these, though it is rather difficult, and the MERV rating generally lower on the scale (MERV 4 or 5). A good rule of thumb is that if you can see your hand through the filter, it isn’t a high-quality filter.
But wait! Air filters come under many different brands and in different sizes – and a variety of MERV ratings. What are these ratings and what do they mean? MERV is an acronym for “Minimum Efficiency Reporting Value,” or how effective the filter. Filters have a scale of 1 to 16 for MERV ratings. Similar to the MPG on a car, the higher the MERV, the better it filters a building’s air. Filters are made up of porous material; the holes in the filter get smaller as the MERV rating increases because it is capturing tinier airborne particles.
When it comes to selecting the best one for your home, there are a few things to consider. Filters on many websites are nominally sized, which means the dimensions – 20” x 25”, for example – are not exact. A filter with this size could truly be 20-1/2” x 25-3/4”. It is okay to have a ¼” or ½” of difference in any of these dimensions. Keep in mind too large of a filter will not fit properly in the allotted space and too small of a filter (leading too large of a gap between the product and the housing) will allow particles and allergens to slip through.
When looking for a replacement, it helps to save part numbers off your dirtied or old filter to ensure you’re getting the same size and type of filter. If you or a loved one has severe allergies, a MERV 13 filter help to eliminate even smaller particles such as micro allergens, smog, and virus carriers.
It is important not to randomly select a filter based on MERV rating alone, however. Since the holes decrease in size with higher MERV rated products, the air works harder to pass through the material. The restricted air flow means your furnace is working hard to spread air throughout the house. For most houses, a good MERV range to stay in is MERV 8 to 12.
If you have additional questions about air filters, MERV ratings, or which one matches the current one in your home, feel free to call us!
And also shop SupplyHouse.com’s full selection of replacement filters here