Rusty Ducts: replace or not??

[visoredge]

Hello,
We just purchased a 45 year old home, and the crawlspace has a moisture issue (which we'll be addressing)
I noticed most of the ductwork down there was rusty looking, and most of the insulation is deteriorated and hanging off.

It's a 2000 SQ ft single level home, do these ducts require replacing (and insulating), just insulating?

Any opinions?

[HVAC Pro]

Where does this thread fit in with your "ripped flexible duct" thread? Or does it?

[framehvac]

Its the slow time of the year someone may give you a good deal if you replace the ducts I would.

[visoredge]

(This thread doesn't fit in with my ripped duct thread)

MOst of the ducts are metal (steel?) and are rusty looking, one duct was made of flex duct and was ripped open...

[HVAC Pro]

I'm with you now. Is this metal duct in a "conditioned" space such as a heated basement or utility room? Or is it in a crawl space or attic? If in an unconditioned space it should be insulated. Sometimes the square or rectangle ducts are "lined" with insulation on the inside. Other times it is "wrapped" on the outside with insulation. I assume since you are seeing rust on it that it's not wrapped. You need to gain access to the inside to see if there is a liner. The rust is from condensation which comes from the cool conditioned air inside cooling off the outside of the duct which is exposed to moist warm air in the summer. There is nothing wrong with a duct that is lined also being wrapped. I would be sure to seal every accessible leak before wrapping however. Depending on how severe this rust is maybe it would be to your advantage to consider replacement.

[visoredge]

Thanks...

It's in my crawl space.

I took some pix, and will try to post some soon.

It's pretty scary down there... with the insulation "dripping" off the metal and just the general mess down there!

[framehvac]

Originally posted by visoredge
Thanks...

It's in my crawl space.

I took some pix, and will try to post some soon.

It's pretty scary down there... with the insulation "dripping" off the metal and just the general mess down there!

In the hvac field we call that at home.

[filterchanger]

This is simple common sense. You breath the air that flows through the ducts, if you want to breath nasty air than leave the ducts alone, if not and you can afford to replace, do it. I ve seen very nasty ducts and i wouldnt want to breath someone elses funk.

[cem-bsee]

ducts rusted some on outside?
some on inside?
both?
rusted thru (with holes)?

joints & seams should be coated with mastic -- then insulated -- AFTER

curing the moisture problem! at least attempting to do so --
dirt floor?
downspouts extended 10ft
dirt drop 6" in 10ft from house?
spring under house?
sump pump?

read at BUILDINGSCIENCE.com

[square2round]

Replace.

Patching ductwork that sounds this bad will just result in the same problem not long after. You'll get your money's worth in replacing rather than patching...that saying it's installed the proper way.

If this is the original ductwork...after 45 years, it sounds like it's past it's prime. Insulation will fall off and galvanized will rust in crawl spaces. Have it replaced.