However, they need to be cleaned out as often as you would replace a disposable one (checking it every month is recommended) so that you have the right amount of air-flow and are not putting undue stress on your furnace. These filters can save money because you don’t have to be buying filters to replace. Permanent reusable filters (also referred to as washable filters) are constructed with either solid aluminum or plastic frame. They come in many standard sizes, but are generally more flimsy and have lower ratings than pleated filters.

They have an almost spider-web appearance and are often blue in color. The price of these filters varies from a couple of dollars all the way up to the $30 – $40 range depending on the brand, size, and MERV rating of the filter.ĭisposable fiberglass filters are the cheapest filter on the market but really aren’t the best furnace filters. Pleated filters are constructed out of paper and polyester and do a good job at filtering most household particles and allergens. These come in a range of standard sizes and ratings. The most common type of furnace filter is a disposable pleated kind. It's a good idea to write this in permanent marker on your furnace so that you can have it visible when you need to know it. You should be able to look at the filter in your furnace currently and see the size printed on the side. A good fit prevents air from slipping around the edges of the filter. It is important to note that you must have an exact fit -“close enough” is not good enough in these circumstances. The filter must fit snugly in your furnace. The easiest way to find out what size you need is to pull out the filter that is currently in your furnace and check it (the size should be written on the frame of the filter) or you can also refer to your furnace manual. Height and length combinations range from 10”x10” all the way to 30”x 30”. The most common thickness is 1”, with 4” also being a popular choice for larger systems. There are a lot of different sizes and you need to use the one that is the correct size for your furnace.įurnace filters are sized by thickness (depth), height, and length. Now, you need to know what size of filter your furnace needs.

Direction of air flow furnace