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gallia 10-16-2010 06:51 AM

Air duct return
 
Just discovered air duct return is opened to the crawl space. Fiber board was used for vent returns, fiber board on ends are either missing or fitted in place, some areas are duct taped. One vent return has a PVC pipe passing through it, used for dryer outlet.
Does not the return need to be air tight? How can this be with fiber and duct tape. No other material or sealing was used. The house is 12 years old. Another concern is, have we been returning crawl space air into our supply and causing a mildew problem? I know the house has a major dust problem, but did not know why. Now knowing air duct is not sealed, things fall in place. Thanks

Thurman 10-16-2010 07:32 AM

IMO: I'm familiar with the fiberboard ducting, but never in a crawlspace, only inside a climate controlled building. I would say YES, you should have all seams, and cracks sealed and duct tape is one of the most common methods of sealing fiberboard. Another, better way is to mix up some mastic sold for this purpose and put on each seam. This is usually applies by hand, wearing rubber gloves. When mixed properly it goes on like, say-peanut butter and hardens well. I would say you are having ambient air within the crawlspace intruding into your ductwork and getting into your home. But--worse yet--you are losing conditioned air into your crawlspace=$ lost. The PVC pipe needs to be re-routed. Having it within your ductwork will cause the humidity within the pipe to condense when the air within the ductwork is cool. This will also cause the condensed humidity to entrap lint within the discharged air and create a blockage. Just my 2 worth. David

gallia 10-16-2010 08:25 AM

Quote:

Originally Posted by Thurman (Post 517658)
IMO: I'm familiar with the fiberboard ducting, but never in a crawlspace, only inside a climate controlled building. I would say YES, you should have all seams, and cracks sealed and duct tape is one of the most common methods of sealing fiberboard. Another, better way is to mix up some mastic sold for this purpose and put on each seam. This is usually applies by hand, wearing rubber gloves. When mixed properly it goes on like, say-peanut butter and hardens well. I would say you are having ambient air within the crawlspace intruding into your ductwork and getting into your home. But--worse yet--you are losing conditioned air into your crawlspace=$ lost. The PVC pipe needs to be re-routed. Having it within your ductwork will cause the humidity within the pipe to condense when the air within the ductwork is cool. This will also cause the condensed humidity to entrap lint within the discharged air and create a blockage. Just my 2 worth. David

I have not been in a chatroom before...hope my reply works...
So you are saying go ahead and use the fiberboard, but seal it with a mastic bond? Out of the six returns, 5 have no tape or sealing on the end pieces. These are just snugged in place. One end missing on 4 of returns. The duct tape they did use was one piece on bottom not on all four sides. Found all this out last Sat., because dryer seem to be sluggish.
Outlet from dryer was plugged with lint due to using 45 feet of PVC piping for exaust with two 90 turns! The air return with the PVC pipe is loaded with lint/dust. Which caused me to look at the other returns, to find the annoying problem we now have. Plus all those years.....of wasting our hard earn $$$$$. I have not had the unit on since the discovery...one would think, a house 12 years old, valued over 200,000 would have a better air return set-up, especially for folks like us who know little about such things. What I have learned via Internet on air returns and what I have discovered in our crawl space, just makes me want to spit...and I am a female...thanks for your advice.

beenthere 10-16-2010 11:05 AM

Quote:

one would think, a house 12 years old, valued over 200,000 would have a better air return set-up,
Sorry. But your house was constructed by the cheapest bidders. Thats how new construction is done. And the subs always look for corners to cut to save them money. Since the builder won't pay for a proper system.

gallia 10-16-2010 12:49 PM

another question on air duct
 
the return material is Celotex Sheatling-Tuff-R Polyisocycnurate foam board, aluminum foil both sides. 1/2 inch. Is this the same as fiber board?
And what do you suggest we use for the duct work, as we plan to hire someone to replace what is now in use.

kenmac 10-16-2010 12:52 PM

I vote for metal


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