Ceiling turns brown on central Air…
h12721
| Posted in Energy, Heating & Insulation on
Hello to all
In August I had a central air conditioner put in the house. All was fine then. But now in the Winter after a cold spell, I see on the outside rim of two outlets on the ceiling brown spots. They look like water leeks. The AC covers fife rooms and one bath room. The leaks are in the bath room and in one room on the cold side of the house,at the end of the duct work. At the beginning of Winter all the outlets and the large inlet in the hall where closed . I did get no response from the installer other that he tells me the roof is leaking which it is not.The attic is R11-R19 insulated. The heating in the house is base board hot water heating.
What would the problem be.
Hilmar in NY State
Edited 2/9/2008 9:45 pm ET by h12721
Replies
In the bathrooms I would suspect rust stains from condensation. Insulation needs checking around the vents and the "paint" for rust.
If the ceiling vent feed duct is on top of the insulation there's a good chance it will be cold enought to form condensation.
Just closing the dampers may not be enough.
I'll assume your none responsive HVAC contractor ran flex duct and terminated it in metal boots cut into the drywall. He likely didn't insulate the boots.
You are getting warm moist air condensing on the boots or in them. Most likely the air is exfiltrating through the cutout for the diffussers. My personel fix would be to climb up there and spray foam each boot and the hole it is setting in. That will insulate and air seal in one application.
Dave, the flex duct is Harmonica type plastic with silver insulation.You pull to stretch. By boots You mean the cone shaped things in the ceiling the outlets to witch the plastic is connected with
"Ty wraps".
The large inlet in the hall, 16x30 or so, should that be closed up also? I have a plywood board in there. The whole mess has to wait now till I come back in three Weeks. Thanks Dave. Hilmar
I think you mean accordion, but yes that is flex duct. The cone shape things in the ceiling that the duct attaches to is the boot. They need to be insulated and the cut out holes in the ceiling also need to be sealed to stop air leaking into the attic.
I'm not sure what the 16x30 opening is. That size may be a return air diffuser if the air handler is in the attic.
If it is, and the air handler is a/c only, I would cut a piece of 1" foamboad to fit inside (under) the grill just to keep cold air from spilling from the attic into the heated spaces. Of course you have to be sure to remove the "plug" before starting the a/c during the cooling season.
Hi Dave,
Yes that is what I mean. Yes the air handler is in the attic. I will
have to check and do these things when I come back.
Thanks again Dave.
Hilmar