Sweating Ducts!


  #1  
Old 08-19-05, 08:03 AM
PAMSLIWOSKI
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Sweating Ducts!

Help!!! Background:
Last month we bought a condo at the beach (mid-atlantic).
The 6 unit building was constructed in the early 70's for seasonal use. In 1982 the seller had installed a heat pump (air handler in a hall closet - next to stack washer/dryer), with condenser on the FLAT! roof. Our unit is one on the top floor. There is no more than 15" from our ceiling to the underside of the roof. In the bathrooms and hallway, the ceiling is dropped (by a foot) to accomodate the metal ductwork. After 5 weeks owning this place, we have discouvered the metal ducts sweating so badly that the (popcorned) sheetrock ceilings are falling 0 from being wet.
We tried cutting out the sheetrock and insulating the duct with duct wrap (2" insulating sleeves). The tight space to roof, with framing made it difficult to fully wrap all of the ducts. After this, within about 2 weeks, the insulation had filled with water & was sagging. We poked a hole and more than 2 cups of water spilled out.

My husband thinks the answer is to rip out the hard duct and put in the insulated flex duct. 3 different HVAC contractors have said different things. One wants to change everything - the air handler, condenser and ducts. Another one said to rip out ceilings, insulate above ducts , pull duct down and re-insulate them and re-install the same hard duct. The third wants to change air handler (it is 23 yrs old and very rusty from salt air and from the sweating ducts and plenum leaking on it.) and install insulated flex ducts everywhere.

Does anyone have any other suggestions? THANK YOU !
 
  #2  
Old 08-19-05, 09:24 AM
N
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I think I'd go with the remove ducts, insulate above them (better), re-insulate the ducts, and re-install them. To change out an air handler or condenser unit won't address the problem of warm/hot humid air coming in contact with the cold ducts (the cause of the condensation). No matter what else you do, if you don't address the condensation problem directly it will continue.

You said your roof is flat and about 15" thick. Look around outside of building and on roof and see if there are vents into your attic. If there are none (ie an unvented attic) then you must have a hole or some other source for humid air to enter the roof. It could even be a bathroom or kitchen exhaust fan which instead of venting the humid air to the outside vents it right into the attic, possibly right next to the ducts.

If your roof does have vents, then you have a vented attic and insulating the ducts becomes the first (and pretty much only) alternative you have for keeping the moist, humid air away from the cold duct surfaces.

It's time to play moisture detective. Unless you have an a/c contractor that you REALLY trust I don't think I would relegate the moisture hunt responsibility to him. Most of them are just interested in selling you something new, something that may or may not solve your problem. If you run out of ideas, consider calling an hvac engineer. He/she will be expensive, but cheaper than the damage all this water will eventually do; not to mention what it will do to your property value.

After you get it fixed, let us know what you did.

good luck
 
  #3  
Old 08-19-05, 07:43 PM
L
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Wink sweating duct

well iam guessing its very hot up there so you might want to try adding a supply vent up there to bring down the temp . this should be a cheap fix to stop the sweating . but as far as wraping it with 2in if its that hot up there it will still sweat you might end up insulating inside and out . but id try the ac vent frist
 
 

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