Can you over-insulate a gas boiler jacket??

JUGHNE

I have a NG CI 1973 American Standard 1BJ2-G-10-10/1440. 1.8 million BTUH input. 4563 EDR.
Have it opened for cleaning. Of course the insulation is the 1" figerglass which is now pretty ratty.

At this point it seems like it could use a new insulation jacket.
Some here said they have used standard fiberglass batts.....some advise against it.
And can you install too much thickness on a boiler of this size?

TIA

HVACNUT

If you use thicker than 1", how are you gonna get the jacket back on?

JUGHNE

There is a fair amount of empty space under the jacket.
The beast is 6' tall, 5' wide and 4' deep.

I was going to use standard unfaced fiberglas batts.
Can anyone see any issue with the FG?

kcopp

I would use ROXUL...Rockwool. Better R value. Fireproof.
More stable.

EBEBRATT-Ed

Mineral wool is a bit heavier. I would use fiberglass and spray glue it to the jacket. If you can get 2" in their so much the better

nicholas bonham-carter

Use a non flammable glue, or screws, and washers into the sheet metal from the inside to hold the batts in place as you replace the covers.—NBC