Fiberglass Insulation (I'm Confused)

[cd64133]

I have read a few posts here that describe fiberglass insulation as not being non-combustible and not being safe for soft block off plate or insulating around insert in general.

My local hearth dealer explained that they use regular unfaced fiberglass insulation in their installs and has been this way for many years. They have not had any issues.

I have done some research and found that unfaced fiberglass insulation at the local home improvement stores meets the following requirements:

(broken link removed)

Noncombustibility:
– (ASTM E 136)
Unfaced insulation: Passes the test.

The reason it is important to meet the ASTM E 136 requirement is found in this document. To be a true non-combustible material it must meet the following requirements.
(broken link removed)

So this is where I am confused. According to the links I posted, unfaced fiberglass insulation meets the ASTM E 136 requirements for non-combustible materials. Our local dealer in the Kansas City area insulates this way. Are there other requirements that must be met to insulate around inserts?

 

[Jags]

Without digging up all the regs. I believe it stems from the fact that regular fiberglass has a lower melting point than a proper stack is supposed to handle. I believe the number is 2200 F, but could be wrong.

 

[dsm1212]

I'm trying to figure out myself if this is adequate for a soft block off plate for a pellet insert. I am capping the chimney at the top. So it sounds like installers do this all the time, but it's not safe? How hot does the venting get for a pellet insert?

steve

 

[Wet1]

I'm trying to figure out myself if this is adequate for a soft block off plate for a pellet insert. I am capping the chimney at the top. So it sounds like installers do this all the time, but it's not safe? How hot does the venting get for a pellet insert?

steve

Pellet stove pipe is double wall and doesn't get anywhere near as hot as single wall wood stove pipe can get.