HVAC air filter frame systems are needed to hold the filter in place while air races through the air handler. Depending on what type of air filter you need to have it will impact the filter frame system you'll need. Though most frames themselves are universal the clips that you will need to use will change based on the filter type and efficiency you want to use. Now there are even clipless air filter frame options, but these have their limitations, like not being able to accept box style filters deeper than 4 inches. Navagating these options will get you the proper system and ensure a tight fit so that air has to be treated by the filter before going through the rest of the system.
First, you need to determine if you need an air filter frame or air filter housing. If you need to change the filter bank from the side then you need an air filter housing, if you will be able to change the filters from the front or back of the filter bank, then an air filter frame system is what you need. As a general rule, frames offer better seal integrity and lower bypass than side-access housings for HVAC filters.
Frames are able to offer better sealing because there are clips applying even pressure against teh filter and push it into the gasketing located on the frame itself, side-access tracks rely on clumsier gaskets and air pressure to push the filter into the gasket. The problem is with this much play in the system the filters wobble in the track which can lead to bypass. Unfortunately in an effort to "reduce costs" the side access track is quickly becoming the choice of equipemtn manufacturers.
When it comes to filter clips, there are a few different kinds. You can have knock-on clips which go into generic frames, interfere with the gasket, and allow for significant play which is what we are trying to overcome by using a frame system.
Clips that integrate with a punched air filter frame are on the sides of frame instead of knocking on to where the gasket is - meaning that the clip is independant of the gasket. These style clips also offer a spring design that pulls the filter into frame, or the clip rotates and is held in place by a retainer on the adjoing side of the frame - again this style is superior to knock-on clips because they force the filter into the gasket.
Proper gasket maintenance - replacing as needed - is important to ensure integrity of the frame system. This is much easier on filter frames as they can be more easily accessed than side-access or "slide-tracks" that typically can't be reached across the full witdh as coils, fans, and other equipment is compacted to make the overall size fo the airhandler smaller which makes it cheaper.
Clipless frames are now available and show some promise. Right now the world's largest air fitler manufacturer has patented the clipless design/utility with their FastFrame, but being a copycat industry it won't be long before compaines being trying to get around that patent - time will tell how successful they will be.
HEPA and Carbon filters have different retaining systems and are a topic for a different post.
For more info on filter frames, or to get a recommendation or quote visit our Frames and Housings webpage where you can look at different options and contact us.