adding an air filter

17 years ago

I would like to add a 4" or 5" media air cleaner to my HVAC system. It currently uses a 1" disposable filter that just sits in the bottom of the blower cabinet and lets dirt in around the filter then the evap core plugs up. I'm currently looking at Aprilaire model 4200. I can't find anything the indicates the CFM of the blower on my system.

The air handler is located in an elevated closet that is 1 foot above the slab with return vents in the wall feeding under the closet floor. There is no ductwork for the return just a hole cut in the floor of the closet under the air handler.

I would like to just add the filter housing to the bottom of the floor under the furnace.

Will having only 5 inches of space from the inlet of the filter to the floor cause a problem with air flow?

Will the filter housing need to be supported from the bottom or can it just be mounted to the floor and hang in place?

Thank you.

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Comments (6)

refrigman1
17 years ago
if you post the air handler model number i can tell you the cfm required. Sounds like a good plan. Aprilaire media filters and housings are not very heavy you can mount the housing to the floor and let it hang. The filter housing is plastic so at least six screws with washers should hold it fine
kaffine
Original Author
17 years ago
It is a Trane XL 80

Furnace model number TUD120A960A0

AC model TXC049P5HB0

Thank you.
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refrigman1
17 years ago
ok you have a four ton a/c and a 120k btu furnace with a five ton blower. four ton a/c requires 1600 cfm. five ton blower in the furnace is capable of 2000 cfm (if fan is set to high speed)
ryanhughes
17 years ago
For moving 1600 cfm, a 5 inch clearance from the bottom of the filter enclosure to the floor really doesn't sound sufficient. What do you think refrigman1 or anyone else? The media filter is a great idea for better filtration and less resistance, but it needs to be done right!
refrigman1
17 years ago
i apoligize i did not understand the 5" question. i do think 5" of clearance below the furnace is not sufficient for the amount of air needed. i would suggest maybe getting rid of the vents in the wall that feed the closet space and put one large return opening in the wall and attaching the filter housing to the inside of the wall so that all air entering the closet space must pass through the new filter ( i dont know the exact set up, and if this is even possible.)
kaffine
Original Author
17 years ago
Currently the furnace sits in a closet that is about 47"x42" with the water heater sitting next to it. The floor of the closet is 12" above the slab. There are 3 registers that feed into the space below the furnace that mease 12"x24" the problem is one of them is located in the bathroom and when the door is open it blocks the vent when the door is closed there isn't enough air to feed the vent. The other 2 are located in the hallway.

The filter would be able to draw are from all 4 sides. The Aprilaire 4200 specs show that it is 6 3/4 inches thick so that would leave 5 1/4 inches between it and the floor.

Are there other filter housings that are narrower?

How much space above the floor should I have to be able to supply 2000cfm?

Thank you.