When it comes to furnace filters, size matters. If the filter is too small, it won't cover the entire space and may allow dust and dirt to pass through. This can lead to reduced efficiency of your heating and cooling system, as well as higher utility bills. On the other hand, using an oversized filter can also cause problems, as it can get stuck and damage the HVAC system.
To ensure that your furnace filter is the right size, it's important to understand what the numbers mean and how to measure the filter slot. The first step is to check the manufacturer's specifications or ask your HVAC technician for help choosing the right product. The filters only work if air has to pass through them. The filter has air resistance and a gap does not, so if you leave a gap of 1, a disproportionate amount of air will flow through the hole, making the situation even worse. Using an improperly sized air filter won't necessarily damage the HVAC system, at least not immediately. However, it has an impact.
Using the wrong size reduces the efficiency of your heating and cooling system. This can add up quickly and become a more obvious problem that you're likely to notice on your next utility bill. The oven filters should fit properly, but you don't need to force them to place them in position. If you have to force the filter into its slot, it's probably too big. Forcing an incorrect filter size on a filter can cause it to bend, damage it, or reduce its ability to function properly.
The filters are slightly smaller than their slot for easy replacement. Some HVAC units may need a filter with unique or unusual dimensions. In these cases, it is necessary to request a custom filter. An improperly sized HVAC air filter can compromise the entire system. A filter that is too small or large will not create the seal needed to filter all the air.
The gaps will allow dust, dirt and germs to bypass the filter and potentially re-circulate to the air in your home. To put that into perspective, a 1-inch air filter may need to be changed every month, while a 4-inch air filter could last up to six months. Then use a measuring tape or other measuring device to measure the length, width, and depth of the inner edge of the slot or frame of the air cleaner. If you can't find your size in the store or need a custom-made air filter, online retailers are probably the best option for you. Some air conditioning specialists have also found that thicker filters are better at providing a perfect fit that doesn't allow unfiltered air to pass through. If you're considering a thicker air filter to improve air quality, it may be best to focus on the MERV rating.
It's a common misconception that using an air filter with a higher MERV (Minimum Efficiency Report Value) rating is the best option. For example, a filter labeled 10 X 12 X 1 is 10 inches long, 12 inches wide, and one inch thick. If you try to use a 4-inch thick air filter for a system that is made for a 1-inch thick filter, the efficiency will actually be worse. The smaller filter area will behave like a filter that is already partially dirty, but you can use it temporarily. If an oversized filter gets stuck where it doesn't belong, it can damage the HVAC system and not clean the air properly. When you buy a filter online, the actual size appears at some point in the product vignette or in the product description. For common HVAC system brands such as Goodman, Lennox, Trane, Rheem York, Coleman and Carrier, most standard air filter sizes will work.
Still, understanding the most common air filter size can be difficult if you're not sure what the numbers mean. Note that the size that appears in bold on the filter frame is the nominal size of the filter, which is likely to differ from its actual size.