Posted on 06/29/2011 9:50:55 AM PDT by JerseyHighlander
The return is in the ceiling, the unit is in the attic.
There’s your trouble. Seal all the cabinet seams (ductseal) and return seams and duct tape the filter access door.
Duct tape will stay put on solid, clean metal ducts but this does not sound like what was added to the house.
Did the house have central heating before the A/C was added? Does A/C use a separate set of supply ducts than heating (theoretically more efficient, because it’s better for cold air to come from the top of rooms while hot air should come from baseboard level, but leakage from one set of ducts to another can carry dust).
If the attic is being over pressurized (say by leakage at the new registers) it should be obvious upon popping the attic hatch door open. While leaks should be addressed (check that the register boots seal all the way from where the ducts attach to them to the register covers, and don’t have any fiberglass tucked inside) it’s also possible to ventilate the attic itself with a wind-powered roof vent or two.
A sloppy filter access door fit can allow ambient air in or conditioned (heated/cooled) air to escape, however taping it shut isn’t wise since that filter WILL need replacement every few months. If enclosed by a door, self stick weather stripping (if such a seal is not already designed in) will help keep air from leaking into or out of the filter area. If it was a half-@$$ job with the filter sliding into a slot that stays open on the end, then lean on the contractor for a better installation, and no just covering the end with duct tape is not acceptable.
Gaskets would be better it they work, the tape will have to do if not.
That would be the 3M 425 tape. Check the price on the internet, while you’re sitting down, strapped in and without food or drink. I think it’s about $70 per roll. Then compare to prices on eBay. Should be able to get it for under $30 per roll if you’re patient.
Check inside the duct as well. If the installer dragged it threw the attic he could have gotten some debris inside the duct.
I also agree it could be a leak on the supply side.
OK, I just finished sealing up the inside of return around the filter using some proper HVAC tape, sealed the outside of the return filter cabinet in the attic, and (re)sealed the outside of the main return cabinet in the attic on every joint and area that the rolled aluminum is jointed. Seams the return cabinet was tweaked to fit inside the slightly less than 16” rafter space, bending the cabinet some, which seams to be a possible source.
I’m not going to tape the filter access door, that’s not the source.
Also found a supply side leak at the T junction of the main duct and a side duct, tried taping that up, but not sure how successful.
Will try to grab a smoke pencil tomorrow and see if I can get up there and pinpoint the leak(s).
I’m using Nashua 324A tape, only thing I could find locally. My understanding is this should be good enough.
If it isn’t let me know please.
I don’t know. The 3m tape I mentioned is used for aircraft repair. It may be overkill in your situation.
If you wanted to be adamant, you could insist on a new cabinet installed properly (in a frame built atop the rafters) rather than putting up with a bent one. I hope you can get at the filter door through the ceiling, rather than needing to go up in the "cozy" attic during the A/C season.
Should (the good Lord forbid) an F5 tornado strike and mow the house down, the ductwork will eventually be found somewhere with the aircraft tape still attached!
Sounds like you are on it. Good for you.
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