53flyer
New Member
DAKSY said:You will get answers both ways on this one.
I, for one, agree with your chimney sweep.
I installed wood inserts (& stoves) for 5 yrs before
moving to the sales floor & EVERY one of them - in a masonry fire place -
is installed with unfaced fiberglass insulation
both UNDER the cap & in the damper area.
NOT ONCE has there been an issue with ANY of these installs.
Fiberglass does not melt. It does not outgas. It works, period.
I pulled my 3100L out of my fire place after 4 yrs of burning it
as a primary heat source - 4 -5 cords per year - & the fiberglass looked
& felt EXACTLY the same as the day I installed it.
It was NOT melted, discolored, ordeteriorated
in ANY way.
We can battle this all we want & folks here will continue to disagree,
so you can take what you want from both sides of the argument.
I've worked for this company for 9+ yrs, & the owner started the business
in 1977 in his garage. He is one of the more respected voices in the field of
wood burning & in fact his input is directly felt by anyone here who has taken the
NFI Certification Exam for wood burning. He is part of the board assembled to
develop the questions & answers, & under HIS direction,
we install with unfaced fiberglass, because it's safe to use
& it works very well...
Hi DAKSY,
I read your reply to a forum Q irt insulating top cap and damper area with unfaced insulation. I actually just bought some Johns Manville R-30 unfaced fiberglass to use and wanted to ask a few follow up Q's relating to it.
I called the manufacturer and he said the only thing that will break down in their insulation that's made for home construction is the binding agent. He said that could occur around 400 deg. He said they make another version of their insulation for commercial and OEM use that doesn't have that binder and is a much higher temp product.
1. Do you know if the fiberglass insulation you use is the typical home insulation or perhaps the other (higher temp rated) fiberglass insulation the Johns Manville rep described?
2. When you pulled your 3100L was the fiberglass you referred to used around the surround, up in the damper area, or even higher up in the smokeshelf area? I imagine the fiberglass used between the surround and the fireplace exterior rarely experiences temps above 150-200 deg whereas insulation used in the damper area (in direct contact with the exterior of the SS liner) may routinely experience temps much higher (perhaps as high as 400-500 deg 18" up at the damper level and 300-400 deg 24-30" up at smokeshelf level?). Do those temps seem like good estimates to everyone?
I'm not concerned about the temps under the top plate. I doubt it ever hits 150deg 17ft up from the stove top in a masonry fireplace that's exposed to the outside air for the last 8ft (first 6.5ft is in the middle of the house, next 2.5ft goes through an attic space). The smokeshelf area is where I'm wondering how hot I should expect the exterior of the SS liner to get to. Since my smokeshelf is 3ft above the stove top I figured the exterior of the SS liner would be hard pressed to get to 400deg.
Could someone tell me how high the temps are 3ft up on the exterior of their single ply liners/pipes?
Thanks,
53flyer