Which Furnace or AC Filter Should I Buy?

Most people do not consider and may not even be aware of the many different options available for furnace and AC filters. While a standard pleated filter is most likely sufficient for your needs, there are several other options that may be more ideal for your specific situation. The MERV (Minimum Efficiency Reporting Value) rating for furnace filters determines which contaminants your filter will remove, as well as the percentage of removal, and remains a constant guide for all of the different types of filters, with the exception of fiberglass. However, it’s important to keep in mind that the MERV rating you can select for your filter will be determined by your specific furnace or AC unit.

Pleated Filters

Pleated filters are the most common types of furnace filters and include the vast majority of filters on the market (most notably the standard 3M Filtrete filters). Pleated types are the most common types because they are, in general, the most cost-effective. They come in a variety of different MERV ratings and are compatible with nearly all furnace units.

Fiberglass Filters

Fiberglass filters are the least efficient of all furnace/AC filters, with the highest MERV rating available for this type being only 3. A MERV rating this low will typically cause the coils of your furnace to collect any excess dust and debris that the filter is incapable of removing, causing damage to your unit over time. These types are often recommended by HVAC contractors only due to their high flow rate, but they do not result in the best value in the long run. While it may seem like a good deal at the time, you should definitely be wary of fiberglass types and those who recommend them.

Washable Filters

Washable types generally cost much more than pleated and fiberglass filters, because they are cleanable and reusable. While the concept of a washable filter certainly seems cost-effective and environmentally-friendly, a furnace filter can, unfortunately, never be fully cleaned. Over time, washable filters do lose efficiency and filtration power due to the build-up of dust, debris, and other air contaminants in the filter that cannot be washed away.

Odor Eliminator Filters

In addition to the removal of standard air contaminants, odor eliminator filters are designed to do just what their name describes – eliminate odors. These filters are infused with activated carbon, which naturally eliminates odor. The carbon in these filters will also remove organic vapors from toxic chemicals. These types of filters are ideal for homes that have issues with pet odors, tobacco smoke, and other odor-causing agents that are not easily removed or masked by an air freshener.