Can I Use 4 1-Inch Filters Instead of a 4-Inch Filter?

When it comes to oven filters, the efficiency of the filter depends on the size of the oven. If the filter slot is wide enough to fit a 4-inch thick filter, then you can use it. However, if the slot is less than 4 inches wide, then you won't be able to use that thickness. To help you understand this better, we've broken down the comparison between 4-inch and 1-inch oven filters. As a home inspector, I recommend installing a 4- to 5-inch media filter if possible for your system.

Most HVAC systems can be adapted to fit these thicker, high-efficiency filters. For example, there may be a 20 x 30 x 1 label on your filter label, but if you measure the filter, you'll see that the actual size is smaller than the nominal air filter size of 20 x 30 x 1.It can be 19.75 x 29.75 x, 75 in real size. Lennox X6672 HCF16-16 Healthy Climate 16x25x5 Merv 16 filter. A 4-inch thick filter has approximately twice as many surface areas as a 2-inch thick filter. If the filter does not have the actual dimensions on the outside of the filter, you can measure it to get the correct dimensions.

Most HVAC technicians recommend changing 1-inch air filters every 30 days, while 4-inch filters can be changed every 3 to 6 months. When you buy a filter online, the actual size appears at some point in the product vignette or in the product description. These 4-inch multimedia filters can have between 20 and 30 feet of surface area with their pleated (accordion) filter material. When it comes to a head-to-head comparison between a 1-inch and 4-inch oven filter before selecting the next filter replacement, these media filters have much stiffer cardboard frames, and some media filters even have plastic “rails” on the top and bottom so you can slide them inside the oven with a very tight seal. If you put several 1-inch filters together, it's similar to putting together 5 coffee filters and trying to make a cup of coffee - it just doesn't work. Replacing the standard one-inch air filter with a 5-inch pleated filter can improve the air quality inside your home.

When you buy your air filter online, it's important to know that air filters have two sizes: the nominal size (which is a round size often used to label the filter) and the actual size. However, with most HVAC systems, you should be able to modernize a media filter cabinet, either under the oven or on the side. Virtually any HVAC professional will tell you that thicker filters work better than common 1-inch oven filters. Not understanding these numbers often leads to consumers buying a filter that doesn't fit their heating or HVAC system.

Ben Depauw
Ben Depauw

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