Condensation on duct work

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Old 08-08-09, 08:04 AM
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Condensation on duct work

I have a older house that recently had a central air unit installed in a existing furnace and ductwork. The ductwork is in an uninsulated crawl space with dirt floor.
I had to go under the house over the weekend and noticed that the ductwork is "sweating" profusely.

I am on a fixed income (retired) so can't afford a expensive fix.
Is there a solution that I could do myself (reasonable handy, some physical limitations, but not to the point that can't do DIY work.

If insulating the ductwork is the answer, wht type of insulation should I use?

Thank you
Vic
 
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Old 08-08-09, 09:00 AM
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You can insulate the duct, but the larger problem is that a over-sized (too great cooling capacity for the space being cooled) AC unit may have been installed.
 
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Old 08-08-09, 07:01 PM
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Insulating the duct work with 3in wrap is the first step that should take place. Make sure all seams on return and supply or sealed with duct seal. 2nd would be to install a VP on the ground and up the walls to dirt level. If you are in a green grass state close the vents. If you have a fossil foil furnace don't close the vents if it does not have make up air.
 
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Old 08-11-09, 12:56 PM
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Insulating Ductwork

airman.1994,
Thanks for the information on what I need to do, couple of questions,
You say wrap with 3 inch insulation, what type of insulation is that? Do I need to dry the condensation offf the metal before wrapping?

You say to close the vents if i am in a green grass state, I am not familuar with that term so i am not sure if I am or not. I am in Washington Indiana.

Thanks again!!

Vic
 
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Old 08-11-09, 01:14 PM
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Hey Vic...another Vic here, grew up in OH.

Anyway..yes..you are in a green grass state...most of the midwest and mid south is.

I don't think it would be good to wrap the insulation over the condensation IMO, but I think I would just wait until its cool enough to leave the A/C off for a while so there is no condensation.

You said it was installed recently..maybe you should have the company that did it come back? They would be able to get the materials cheaper most likely..though some HVAC companys will sell to homeowners for small amounts of this kind of thing.

Airman will be back to answer the type of insulation question.
 
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Old 08-11-09, 07:43 PM
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I'm back! Duct wrap is insulation that is made for duct work. 3in will come in a roll 75 feet long by 4 ft wide. Green grass state is anywhere that is humid and sees enough rain to grow grass with out the need to water it.
 
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Old 08-12-09, 02:46 AM
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Thanks again.
Do you recommend the non fiberglass type of duct wrap? I wasa thinking that the fiberglass would tend to get damp and lose its insulating properties.


Thanks again!!
 
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Old 08-12-09, 04:35 AM
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If all seams are sealed it should not get wet!
 
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