I visited a customer’s house yesterday regarding a complaint of water leaking in the ceiling of one of their bedrooms. We did the roof 5 years ago so they thought that was the problem. Upon inspecting the attic, I found that they have an air conditioner unit installed in the attic with flexible insulated ductwork running to the various rooms through the ceiling. In the two ducts that fed the bedroom with the problem, there was standing water in both that could be dumped out when lifted (which I did). Farther back in a larger line there was standing water as well. I did not check the remaining ducts.
This seems to be a condensation problem to me. Has anybody run into this before and what was done to solve it? Thanks.
Dopp5
NOTE: The ceiling of the house only had 3-1/2 to 4 inches of insulation.
Replies
The A/C ducts are not used for heating, right?
The problem is not the insulation of the house. It's warm relatively moist inside air being driven by convection through the A/C registers and into the ducts, cooling, and condensing out.
The easy "solution" is to seal up the A/C registers (especially on the top floor of the house) with one of those plastic window film kits (Frost King, etc. available anywhere). I've got the same problem. Better solutions welcome.
This is AC ductwork only. I also recommended closing the vents. The window film is also a good idea - I will pass that one on too. Thanks.
If you could figure out some way to bleed a small amount of heated air through the ducts (going INTO the heated space, not away from it), that would probably do the trick. Also, insulate the ducts with something like fiberglass batts layed over them.
I just discovered the same situation in our house.
It's a cape and the second floor isn't finished yet. The ducts run behind the walls (are those called "knee walls"?) way down in the eaves.
I taped plastic over two of the offending grills and that's seems to be the business.
My grills are plastic with a screw adjustment in the center to close them off but I'm wondering if they were a low-cost product.
This phenomenon is one of the reasons I posted elsewhere about Icynene foam insulation, thinking the entire roof down to the vents would be sealed and the ducts would then be in a conditioned space.
Next time will be a bomb shelter.
Are you saying that putting the plastic over the 2 vents did solve the problem? How long ago did you discover this problem? Thanks.
Yes, covering the vents solved the problem.
I first noticed the problem about a month ago when we had been running a humidifier in our bedroom. (I'm in CT and it was quite a cold January)
One vent very close to the eaves has stains on the sheetrock around the edges but the other just dribbled a bit on the floor.
Plastic over both solved the dripping but I'll have to get up there to wrap insulation around the duct/vent junction and investigate why that one vent drained to the sheetrock.
my cat likes to go white water rafting in our ducts. in a tupperware container. usually happens after drinking a lot of captain morgan.