Seal plenum holes

Hi,
I had my whole hvac system reinstalled last year by a contractor. He moved my evaporator to the attic and did the zoning (I have 4 zones). I have two problems that need some help guys:
1/Some months ago, when the weather was very hot and we used the AC, I noticed there was a lot of condensation under the supply plenum (and dripping on the wood). You can see in my picture, the evaporator Rheem is on the right side and next to it on the left is the supply plenum. I called him and he said that is because there is too much cold air inside when we turn on only one zone. Is that true? Should I buy the duct insulation at Home Depot and wrap it up?

2/ In my other picture, you can see the draining pipe on the right, one bare copper tubing next to it and a wrapped copper tubing on the left (I believe one for hot and one for cold). All coming into the plenum. Last time I checked, the tape (is it butyl? I am not sure) wrapping around the cold copper tubing and the draining pipe came off. Lots of air leaks through as you can see. So the contractor came and took the old black tape off, put new one in, wrap around the new tape with some foam insulation and zip tie them.
Today I checked again, the same thing happened to the hot copper tubing. The butyl taping coming right off the seal deal to massive air flow. My question is what is the right way to seal off those holes on the plenum? Last time when the contractor did with new taping and foam insulation, the holes were kind of tight but not completely since I can still hear the noise of air going through, although not as much as before.

Really thanks for your help and wish you guys a happy holiday :beer:

He used "cork tape" to seal the line. That is standard practice, although I usually see it on cold lines to prevent concensation on the outside of the unit.

You need a new HVAC guy to fix this leak.

Thanks for the reply. Although there are things I can't handle myself and I have to call a contractor, I tried to handle most fixes or at least, understand about it myself.
With that said, how do you wrap the cork tape so it can stay longer? I read somewhere that the cork tape will eventually come off anyway so he has to redo it yearly.
I am trying to think of a way to seal off the hole completely or almost.

I can't speak to _how_ you can solve the issue -- but my first reaction to the cork tape (and no disrespect at all) was that's way too sloppy for a professional --- and I can't imagine the requirement of re-taping it (yearly!).

With all the legit maintenance these things _do_ require I'm amazed there aren't more problems re the lack of said maintenance: How many times have I heard from someone that they're surprised the Air handler needs periodic changing of the filter? More so, what do old folks or the infirm do to change a filter 4 times a year -- when its up in an attic with no floor -- only joists and in a cramped space?

Sorry, i digressed a bit.
It seems a (rubberized) grommet for the task at hand would seal and maintain for years.

HVAC contracting is a scary arena (unlike plumbers and electricians there is no licensing). I'm still trying to find someone competent enough to figure out why my A/C condenser comes on when the tstat call for heat (the heat comes on too). I've given up on that attempt, no one is able.-- I just turn the AC breaker off in the fall and will try someone new the next time I really need help.

I was thinking the same too. HVAC is not my stuff so I am not sure where I can find or what is the trade name for that grommet.
Sorry to hear about your system. It sounds so scary to me.

This wrap is the correct way to seal up the holes.
You may have excessive pressure build up in the plenum when only 1 zone is open.
Your going to have to zip tie that gasket tight to the line so that it doesn't slide back.
Maybe some gasket adhesive on the mating surfaces and allow to dry before pressurizing.
As far as the condensate leak, check the drain lines for blockage and correct pitch.
If discharge is a problem, ask your contractor about installing a condensate pump.

Rokosz: Have you changed your T-Stat to resolve your problem?

kok328 said:

This wrap is the correct way to seal up the holes.
You may have excessive pressure build up in the plenum when only 1 zone is open.
Your going to have to zip tie that gasket tight to the line so that it doesn't slide back.
Maybe some gasket adhesive on the mating surfaces and allow to dry before pressurizing.
As far as the condensate leak, check the drain lines for blockage and correct pitch.
If discharge is a problem, ask your contractor about installing a condensate pump.

Rokosz: Have you changed your T-Stat to resolve your problem?

Click to expand...

Thanks for the reply kok. It is not leaking. It is just the plenum is sweating when we run the AC in hot summer. Is wrapping the plenum with a layer of duct wrap a good idea?
Regarding the holes, last time he came and zip tie them up and there is still air leak, at least I can feel it with my hand

No don't wrap the plenum. You need to move more air through the duct when using the A/C.
Also, try a wad of plumbers putty to seal up your A/C lines.