You do have a lot of options, but don't be overwhelmed—we make figuring out which filter to buy a simple, painless process. Here are the factors to consider:
Size: Obviously, your filter has to fit the opening in your furnace. But it's not quite that simple. There are actual sizes (the size of the opening) and nominal sizes (the size printed on the side of the old filter you're replacing, which is often sort of a “rounded off” version of the actual size). For example, if the actual size of the opening in your furnace is 13 ½ inches by 13 ½ inches, the nominal size of the filter you need is 14 by 14. So, when you're ordering a filter, just be aware that if you're ordering a particular size based on measuring the size of the opening, you should order by “actual size.” If you're ordering based on the numbers on the side of the filter you're replacing, you should order by “nominal size.”
MERV ratings:This industry-standard rating system measures how efficiently a particular furnace filter filters out particles in the air. Residential filters all have a MERV rating between 1 and 16, 1 being the least efficient and 16 the most efficient. We sell filters with MERV ratings ranging from 6 to 13, which represent the efficiency ratings appropriate for most homes.
OEM vs. aftermarket filters: An Original Equipment Manufacturer, or OEM, filter, is made by the same company that made your furnace. Aftermarket filters are produced by a third-party company, and are designed to be a physical match to your original filter. Both have their advantages. While you can be certain that an OEM filter will meet the specifications that the manufacturer set for your furnace, aftermarket filters sometimes provide features—such as a different MERV rating, easier-to-replace design, odor blocking, etc.—that an OEM filter does not. In addition, aftermarket filters often cost less than OEM filters. As when you are comparing any two filters, filtration efficiency, quality of construction and price are the key factors to consider.
Odor elimination: Carbon-impregnated filters absorbs odors in the air as well as filter particles. These types of filters can be a good choice if you have pets or other sources of odors in your home.