Condensation On Plenum

[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.

[richmod]

Any uninsulated plenum in a non conditioned space is going to be creating a small flood, not just a little condensation.

It's not just a little condensation - the whole plenum is covered with condensation, and there is actually a small pool of water under it now, though not a flood.

[richmod]

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.

I'm in North Carolina, so yep - pretty humid down there right now. And yes - it is duct lined - 2 zone ducts, bypass duct, and return duct.

Tech's coming next week - thanks for all the info and opinions.

[superd77]

I'm in North Carolina, so yep - pretty humid down there right now. And yes - it is duct lined - 2 zone ducts, bypass duct, and return duct.

Tech's coming next week - thanks for all the info and opinions.

Dude, you are totally welcome!!

[kkmcewen]

My plenum is in the attic. It is insulated in the inside with insulation. I don't notice condensation all the time, just some times. Should I be concerned or does this just happen sometimes?