I think the filters used are designed to filter high volumes of air moving at a relatively low speed - think about how they fit in a home central air system, they’re at the very end of the system before the fan and they have an entire house of ductwork between the blower and them.
Having built one, I don’t see any way the filter stands up to a box fan at high from 12” away. The filters are just media reinforced by cardboard.
A furnace fan will move a lot more air than a box fan would.
The reinforcement on the filters really depends on how much filtering they do. For example, this filter[0] has metal to help keep the filter media in place, but this one[1] has nothing.
The key difference is the MERV rating, the first one is a 13, the second is a 2. The higher the rating the more it filters, but the higher rating also makes it more difficult for the fan to pull air through and require better reinforcements to prevent the filter from getting sucked into the fan.
Comments
I think the filters used are designed to filter high volumes of air moving at a relatively low speed - think about how they fit in a home central air system, they’re at the very end of the system before the fan and they have an entire house of ductwork between the blower and them.
Having built one, I don’t see any way the filter stands up to a box fan at high from 12” away. The filters are just media reinforced by cardboard.
A furnace fan will move a lot more air than a box fan would.
The reinforcement on the filters really depends on how much filtering they do. For example, this filter[0] has metal to help keep the filter media in place, but this one[1] has nothing.
The key difference is the MERV rating, the first one is a 13, the second is a 2. The higher the rating the more it filters, but the higher rating also makes it more difficult for the fan to pull air through and require better reinforcements to prevent the filter from getting sucked into the fan.
[0] https://www.homedepot.ca/product/filtrete-filters-healthy-li...
[1] https://www.homedepot.ca/product/hdx-20x20x1-fiberglass-air-...