Sealing plenum box insulation internal

[?Confused]

Is it ok to have the insulation inside of a plenum box sealed if it is disintegrating or old? I know it can also be replaced but is sealing it also ok to do? Are the sealers used in the hvac field safe ?

[catmanacman]

ifit is fallng apart have it removed and the outside wrapped with duct wrap

[?Confused]

ifit is fallng apart have it removed and the outside wrapped with duct wrap

So by removing it will the inside have to be sealed to avoid any loose debree blowing out as it does now? The person doing the job gave me the option of sealing the inside with a sealer over the existing insulation vs replacing the box which would be more expensive and a lot of work since all the metal ducts have to be cut. I am afraid the sealer is or can be toxic for indoor use in the plenum specially since the air is distributed from this box.

[energy_rater_La]

the system wasn't sealed properly to start with
the sealer is a bandaid for another problem.
the insulation shouldn't disintergrate.


I usually replace supply plenum and mastic seal all joints.
paint on mastic is cheap..its the labor that costs.
but it also gives you a chance to space ducts so that they don't touch
and don't tap off end cap or too close to ahu
and while at it....mastic everything...
.
duct take offs , where plenum connects
to equipment, supply boxes etc.
can you give us more information?
how did you find the problem?
what kind of ductwork? flex or hard pipe?
where are you located?
in hot humid climates ducts shouldn't touch each other
@ plenum ( space them apart) and shouldn't lie or be
buried in insulation because of condensation issues.
it changes for other climates.
and if it is flex, it should be straight runs with no bends
which reduce air flow.

aeroseal is one product, but I don't have much faith in it.
if gaps are over 1/4" wide...it doesn't seal these areas.
as it stays sticky the leaks it doesn't seal still allows
particles to enter and build up through out system.
this is just my experience with this product.

there have been a couple of threads about aeroseal,
just don't know if they were here or pro side.

you may have to educate the installer if you replace the
plenum.
and compare prices of interior sealant vs replacement of plenum.

best of luck.

[?Confused]

I am in hot humid weather location, texas coastal. The ducts are sheet metal, the reason i knew there was a problem was because black dirt soot looking stuff blows out of the duct that is connected the closest to the main plenum box. The insulation in the plenum box is old and disintegrating. The worker said he could seal the insulation in the plenum box, but i am not sure thats what i want done. He is also goimg to replace the duct that is blowing out debris. I might get a second opinion from another company.

[catmanacman]

is it metal or duct board

[?Confused]

Not sure what duct board is but it seems to me made of plain sheet metal