Condensation On Plenum

[kkmcewen]

Is it normal for condensation to be on the outside of plenum in the attic. It was over 100 degrees in the attic and there was slight condenation on the output side of the blower.

[superd77]

You mat have air leaks. Or missing insulation on inside of air handler. Only seen a couple sweat in attics. Both were foamed attics.

[richmod]

How about on the plenum in a crawl space? Our new system has slot of condensation on the plenum. Is that normal?

[superd77]

Do you have a good moisture barrier??

Does rain water get under the house???

Is the crawl damp???

[BALLIN J 23]

To Humid In Attic Call Technician To Look At Duct Work

[richmod]

Do you have a good moisture barrier??

Does rain water get under the house???

Is the crawl damp???

Yes, no, and not really.

Maybe I'm dense, but just making sure - it is normal, correct?

[OOC]

Is it sweating over most of the plenum, or just in a few locations? My old plenum portions (sheet metal, paper wrapped insulation) in the crawl space never sweats except where the insualtion is torn or loose. The new round flex duct the installer used to replace a portion of the plenum sweats over most of it. I have a vented crawl space, with a pretty decent moisture barrier on the ground.

[richmod]

Is it sweating over most of the plenum, or just in a few locations? My old plenum portions (sheet metal, paper wrapped insulation) in the crawl space never sweats except where the insualtion is torn or loose. The new round flex duct the installer used to replace a portion of the plenum sweats over most of it. I have a vented crawl space, with a pretty decent moisture barrier on the ground.

My plenum is sheet metal and is NOT insulated - should it be? Only the ductwork is insulated.

[superd77]

Yes, no, and not really.

Maybe I'm dense, but just making sure - it is normal, correct?

Ducts sweat in crawlspaces in the south. May need to and insulation.

[superd77]

My plenum is sheet metal and is NOT insulated - should it be? Only the ductwork is insulated.

YEP!!!

[richmod]

YEP!!!

What are the consequences of consensation if I don't insulate the plenum?

[superd77]

What are the consequences of consensation if I don't insulate the plenum?

MOLD AND MILDEW!!!!!!!

[cnpro18]

What is the temp. diff between the supply and the return. Coil could be too cold.

[thandar56]

My plenum is sheet metal and is NOT insulated - should it be? Only the ductwork is insulated.

the plenum is located in non-conditioned space it has to be insulated

[superd77]

What is the temp. diff between the supply and the return. Coil could be too cold.

The dude has a uninsulated plenum in a crawl, its gonna sweat regardless of coil temp.

[richmod]

What is the temp. diff between the supply and the return. Coil could be too cold.

Don't know - how would I measure it?

Of coil is too cold, can that be adjusted on the AHU?

[richmod]

the plenum is located in non-conditioned space it has to be insulated

Is that a requirement? If so, I'll be sure to advise the tech as such.

[cnpro18]

The dude has a uninsulated plenum in a crawl, its gonna sweat regardless of coil temp.

Any uninsulated plenum in a non conditioned space is going to be creating a small flood, not just a little condensation. Sounds like it may be internally insulated and Mr. homeowner doesn't know any better. I've seen plenums sweat in conditioned spaces if coil is too cold due to some other problem.

[cnpro18]

Don't know - how would I measure it?

Of coil is too cold, can that be adjusted on the AHU?

You would need to call a tech to come check it out.

[superd77]

You would need to call a tech to come check it out.

If its cooling fine, chances are he's got a humid crawl.

And yes , it probably is a duct lined plenum with a few air leaks.