Step 1: Measure the length and width (L x W). If the filter is not a square, the smallest measurement comes first). Hello, my heating unit is FG7SA-045C-23A. An excellent resource to help you is the U.S.
Environmental Protection Agency (EPA) Home Air Filter Guide. UU. Please note that most disposable air filters are trimmed (this is an industry standard) from ¼ to ½. When you buy air filters, you will see the words “nominal size” and “actual size” together.
The shape and size dictate the ability of the air filter element to flow the maximum amount of air into the engine. Forcing an incorrect filter size on a filter can cause it to bend, damage the filter, or reduce its ability to function properly. Some brands have a foam gasket on the outside of the filter, in this case, you'll want to make sure you have a compatible actual size and that you also have the foam to ensure a perfect fit. If the filter does not have actual dimensions on the outside of the filter, you can measure the filter to get the correct dimensions.
In addition, the properly sized air cleaner assembly with a high flow element can increase the amount of air flow in the carburetor. The tests of K&N have shown that for most two-barrel and four-barrel carburettors, the air flow is greater when the diameter of the air filter is large compared to the height. Unfortunately, that's not the case: there are about 20" standard sizes for air filters and none have the same measurements. The actual size is the exact size of the air filter and the actual dimensions when measuring length, width and depth (thickness).
We recommend removing the existing filter and measuring the filter to confirm the actual dimensions. It is not necessary for the filters to have a “hermetic seal”, but you should be able to easily install and uninstall the filter effortlessly, plus the filter should not be so small as to move freely within the unit. If you can't find a standard size filter within that parameter, you'll need to order a custom-sized air filter. But more importantly, those filters were used to straighten and diffuse air before it entered the carburettors.