Rusty ducts is it a problem?

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  #1  
Old 10-14-06, 10:18 PM
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Question Rusty ducts is it a problem?

We are thinking replacing our old (36 years old) ductwork mainly because it looks rusty on the outside. The ducts are round sheet metal and are in a ventilated crawl space. The insulation is deteriorated.

Here are the questions:
If it looks rusty on the outside does it mean it is rusty on the inside ? Would that be a health issue?
It looks like most of the contractors use insulated wireflex (plastic) is it a good product? Another one is wireflex metal is it better than plastic?
What is the best way to connect those wireflex ducts? Sealant, mastic or special duct tape?
Or should we just re-insulate the existing ducts and not do any
replacement?
We are concerned about the rust, the quality of those flex plastic ducts compare to the hard pipe we have, concerned about the new installation...connections not well done and so on...we just don't know what to do.

We hope to receive some answers.
Thanks
 
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Old 10-15-06, 08:27 AM
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Sounds like you need to fix the crawl space before you do the duct. So new duct will not have the same problem.
 
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Old 10-15-06, 12:54 PM
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Arrow Rusty ducts

Originally Posted by airman.1994
Sounds like you need to fix the crawl space before you do the duct. So new duct will not have the same problem.
There is nothing wrong with the crawl space....it is well ventilated ....We live in Sunnyvale California (San Francisco South Bay) all the houses are built this way. The reason it is rusty is probably because the ducts are old. ( 35 years old)
 
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Old 10-15-06, 08:04 PM
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Reason it is rusty is because their is to much humidity! Id fix the crawl-space first.
 
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Old 10-16-06, 11:15 PM
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Wink

Im with airman.1994.
Start and fix that crawl space first. that is why the duct are rusty. You want to close the crawl space up first. the let some AC and heat out down there. Go to and read http://aboutsavingheat.com/crawlspace.html

Power use comes out about 15% less. Pipe wont sweat . Any and all flex pipe has much more drag on the air than the metal pipe does
The pipe is just rusty on the out side not the inside. This is from the vents open and let the warm moist air into it to make the pipes sweat when the AC is on. if you have insulation in the floor joist Ill bet it is also damp or wet

ED
 
 

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