Confused with Air Filters
I am confused about my air filter size and placement.
The A/C unit is in the attic. The air inlet door/vent is downstairs near the thermostat. Behind the door/vent, is basically a cutout opening. It is about 20x40 in size, but looks like it was cutout with a blade. I can stick my head in there and look upward. It is basically a giant insulated chamber leading to a duct that goes into the inlet side of the A/C unit. The unit has a sticker that says the filters are located elsewhere ( or not in the unit itself) and that the correct size should be used. It doesn't say much else.
I am assuming the filters go behind the door/vent downstairs, over the 20x40 cutout. I have been putting two 20x20x1 filters, one stacked above the other, taped together.
What size filters should I be using, and is there possibly something missing that holds the filters?
Pictures would be helpful. All air must pass through the filters or they are useless.
Here are the pictures in order, from the opening to the A/C unit #1-#5. #6 is with filters.
1 - Without Filters:
2 - Inside of that opening, looking upward:
3 - Attic view of duct where picture 2 goes:
4 - Between that duct and the A/C unit:
5 - A/C unit from there:
6 - The opening with filters in place:
Is that the only return in your home? Can you post the diameter of the flexible duct connecting the return drop to the return plenum attached to the furnace? Hard to tell from the pictures, but looks like a 14" which may or may not be enough capacity for your system. Do you have model numbers you can post of the equipment? This will tell us sizing information.
If you want to use one filter, you can install one at the furnace itself.
Yes, that is the only return. I will measure tomorrow and get the model numbers. Where would I install the one filter?
Thank you for the help.
There should be a 1" filter rack internal to the furnace, right between the return plenum (where the flex duct attaches) and the unit itself. You'll have to remove the access door (and peel back some foil tape) to see what size it requires. However, you will have less pressure drop using two filters as you have been doing in the past (more surface area, less velocity).
Originally Posted by David1000
The duct is 18". The label says "Filters should be installed external to the furnace casing". It is a York, but I do not see any model numbers. I am kind of expecting some filter holder or something more professional than a 40x20 cutout (and not that straight of a cutout).
I don't understand. Pic 1 is a 1" FILTER GRILL. Put a filter in it! If it measures 20x40, then put a 20"x40"x1" filter in it.
I cannot find 40x20 filters anywhere, including Lowes, Home Depot, Wal Mart, and local hardware stores. Do you know anywhere that sells them other special order online? Also, it doesn't seem like a filter holder, but just an opening where a holder should go. I'll do that though.
Taping two 20x20x1 filters like you have is fine as long as its secure and doesn't break in two. If you do find 20x40 filters they will likely be 4x the cost of 20x20s because they are uncommon size. The best thing you could do is have a contractor install a 5" media filter on the furnace.
It's probably a 20x36. Measure the inside opening of the part that is screwed to the wall. You'll notice a lip, the filter sits against that to keep it from being sucked in. It's a standard filter frame, which should hold a standard filter. Not sure I've seen a 20x40 before.
I like DIY'ers. They pay better to fix.
it looks like a return air filter grill to me.
in pic 1 when the return air filter grill door is opened, there is a 1" space where the filter goes.
the lip holds it in place to keep it from falling into the return.
2) 20x20 filters is what I'd do..you won't find a 20x40.
what it looks like you are doing, is putting the filter behind the lip, and in front
of the ductboard cut out.
oh, and you can cut the ductboard to the same size as the opening for the
return air filter grill.
btw, nice job locating the r/a in a corner, forming a triangular chase,
and the ductboard sealing it air tight. also, ductboard install in attic
nice supply air trunk line...from what I can see.
nice to see duct board done well.
if more hvac companies did this kind of work, the bad refrences to duct
board would be much less. and using a corner for return chase...much
easier for homeowner to give up than half a closet!
model number is inside the access panel of the 80% gas furnace.
best of luck
The cure of the part should not be attempted without the cure of the whole. ~Plato