poor furnace/ac filter fit

[coloradotrout]

My filter is on the inside of the blower box just ahead of the fan. When the blower is running, it naturally tends to pull the filter towards it. To hold the filter in place, two heavy guage wires wedged into the upper left and right edge of the filter (and down against the floor) and the bottom of the filter kinda/sortta sits in make-shift ledge.

Seems to me a better design would be to relocate the filter outside the blower box so it is pulled tight against the box when running.

But the area outside the opening to the box is 22" wide. The filter I have now is 16x25, and the next smallest I see 16x20. That would mean somehow making the opening smaller. and then what impact on airflow?

any other ideas?

[coloradotrout]

the real issue is that the 16x25 filter has to be bent to pry into place. In so doing, I mess up the pleated filter and my theory is that then the pleats are collapsing during operation and restricting airflow significantly.

I really want a good filter to filter out some alergens, etc. Using

3m filtrete extra/ultra

[-D]

extra/ultra

Find out what the water column pressure drop is across that filter and post it here. Pleated filters can drop your airflow considerably. There should be a simple way to hold that filter down. -D

[George E. Cawthon]

I don't see what the problem is, that is exactly how my former furnace worked. If you insist on changing it don get stuck on having the filter lie flat. If you put the filter at an angle you can use a much longer one and have much better efficiency. Lots of systems are like that. In mine, you slide the filter in vertically through a narrow tall door, then let flop down until it hits the opposite wall and it is at an angle of about 30 degrees. And, you don't get stuck on having the filter perfectly sealed. The next time the air comes around the particles are likely to get stuck in the air filter, assuming that you change your filters at reasonable intervals.

[coloradotrout]

simple is good

the simple way would have been for the original installer to THINK (maybe that costs extra these days.. or could it be that there is a shortage..mmm)

I would think that a pleated filter needs to fit flat. I have to cram mine in.. and in the process fold it some. That results in the wires coming off the pleats.. thus they are likely to fold under pressure (literally).

Then to keep it in, I have to use those 2 wires to wedge up against the top corners. (wire running from top left corner of filter to bottom left corner of floor) The bottom does not fit flat.. as the fan mount extends up to the air opening. So.. if you can visualize..

With it wedged in there.. it kinda works. But I cringe everytime I put the cover back on! How hard would it have been to devise a ledge for the filter to rest against. and a simple exterior access door? Impossible I gather.

Any suggestions appreciated.

[coloradotrout]

the tilting idea is worthy; more surface area; that i need

i will have another look

The issue is my opening from return is right next to the blower unit. I don't really have a way to tip the filter. It would tip against the fan unit -- which -- I suppose could work, but just flopping there loose.

[George E. Cawthon]

I can visualize that. Do you have a downdraft and where is the furnace? If you have some space another option is to use two filter held in a V, lots more filter in less space, but may be hard to fabricate.

Another thought if you don't have enough space above the blower is to simply put the filters in the cold air returns. That would be practical and easy to fabricate if you have 4 or less (and way more efficient for air passage). Could be a real hassel if you have returns in every room.

[coloradotrout]

like those thoughts..

the "v" idea.. mmmm.. will have to think about that

i thought about moving the filter to a different spot in the cold air return flow. furnace is in basement, but there are two bsmt return vents plugged in right next to the furnace (so I cannot tap in after those since they are so low in the return air channel).

I have 2 returns upstairs and 2 downstairs. I think it would be good if I did have a return in each of the upstairs BRs (3), so that is something I'm looking at doing. That does kinda make the idea of filter at each vent a challenge.

Upstairs I have one return high up the wall in our vaulted room (good for AC) and one in the hallway. Downstairs there is one between the furnace room and the open finished area outside the furnace. And there is one in a BR that backs up to the furnace room.

The trick is my return air run (what is it really called?) is 23" wide, which gives about 22.5" inside, so the filter closest is 20" as the 24" is too big.

I have a 3" W x 1/2" H galv. metal piece underneath my blower fan. Not sure if it is supporting the blower; though I see the blower attachd from above also. That chunk of metal extends over to the return air inlet, which creates a "bump" that the filter must span. If I get rid of that, then I have a smoother 16" x 25" area that the filter can be placed against. There's still no "frame" for it to rest against.. as it's in the blower box area. There's about 3" between the return inlet and the fan housing. I might be able to somehow fabricate a chunk of sheeting and screw it into place to create a filter "slot".

For returns.. how do I know where, how many, and how large to place? I have 32x10 in the hallway and one on the wall of our only vaulted ceiling room. (ranch home w/ full bsmt) But w/o returns in the 3 BRs, they don't regulate well.

[CBHvac]

How about in all seriousness you get the right filter for it?

22X22X1 is a common size...you didnt say how deep it was...so ...left in the dark there....but, I have yet to see a unit that a filter could not be had for.

[coloradotrout]

The opening between return air and blower box is about 16x22 (the filter that was jammed in there is a 16x25)

There's really no room to create a larger opening, unless I go w/ the tipping idea, but that's tricky also (really no room to tip)

Now thinking of creating a "slot" for the filter by somehow installing a vertical "frame" just inside the blower box which will support the filter btwn the blower box and the incoming return. I'll need to cut away a tab of the blower box, and and cut a frame out of tin and fasten somehow. It can work, but I'm still w/ a 16x25 filter.. and the idea of more surface area would be great.

With no filter, I get very noticeable AIR from the vents throughout the house. With the filter, it's not nearly as noticeable.

[coloradotrout]

since I don't know what Manual D is.. I'm 99% sure they did NOT.

Explain.. and I'll press them.

They did not install the furnace nor ductwork.. just the AC. But the "comfort specialist" said the ducting was adequate.

[CBHvac]

A manual D, is the ACCA guide to insuring that the ductwork is of the correct size, to insure not only correct BTU delivery to each room, but to insure correct sizing of duct to make sure that CFM and velocity are wtihing the correct guidelines for the unit in question. It also takes into consideration, filter area, and all items in the airstream, to maintain the correct static pressure for the unit to operate correctly.