I'm currently using a 20 in. x 25 in. x 1 in. standard pleated furnace air filter (FPR 5, MERV 8). I want to know if this is the right size for my setup, or if I should consider switching to a thicker filter like a 20 in. x 25 in. x 5 in. From the pictures I've shared, there's a noticeable gap after I installed the 20x25x1 filter, which is what I've always used. Can anyone provide some advice or clearer guidelines on this?
3 Answers
It's best to choose a filter that fits snugly in the opening where it's installed. If you have old filters to reference, stick with those measurements. Going with a thicker filter can give you more surface area to catch dust and debris, but just make sure it fits well! Also, keep in mind the difference between nominal size and actual size when shopping for replacements.
From what I've heard, the main purpose of your furnace filter is to protect the furnace, not necessarily to clean the air. Higher MERV ratings can make your furnace work harder, which can be a concern. If you stick with the 1-inch filter, just keep an eye on the gap, as it might lead to issues down the road in terms of air quality.
Make sure the filter fits tightly because if there are gaps, the air will bypass it, which reduces its effectiveness. You want to filter the air properly, so going with the size that fits best is key! Regarding the installation direction, yes, keep the arrow pointing up if that's what the instructions say.