If you go to seminars and classes, such as the one I just went to sponsored by Olympia Chimney Supply, there is often talk about technicians, sweeps, mechanics etc.. that run experiments in customer's homes. Kinda like insulating the air space in a thimble. Will doing this actually burn down someone's home? I don't know for sure, there are many variables...however; as professionals, we are bound by ethics to not "experiment" at a customer's expense. Filling a gap to seal out outside air may seem like logical thing to do. It can be disastrous under the right circumstances if the products you are using were not tested or designed with other materials, such as rock wool insulation etc...
Just look at this video you may understand the properties of Rock Wool a little better! This is what I am talking about!
As they say in the video, "Have you ever seen a rock burn?"
Believe me after seeing this I feel much safer having my pellet pipe surrounded by rock wool than an air space! Wow! ! !
While I haven't ever seen rock burn, though it can be melted under enough heat or pressure, I have seen rock get hot enough to actually catch wood on fire if the wood touches it. It's not about the insulation burning...it's about the transfer of heat from one surface to another. When you insulate something such as the annular space around the thimble you are in fact consolidating the heat from the pipe. Temps that may be 250
on the surface could climb to 400
or more and since there is no vent to allow the heat to escape it just builds...over time the surrounding area starts to pyrolically break down until such a time things go very wrong. If one had a chimney fire in the vent and temps rose up over 1000
, the insulated area could climb well over 1500
which is over the temp the pipe is actually designed to withstand and then the whole vent and or thimble starts to fall apart within the wall.
Don, if you are going to be doing installations, you ought to invest in some formal education aside from what you can troll up from the internet. It's no coincidence that more than 50% of the stoves I go to service are installed wrong and therefore need to be reinstalled properly before I can work on them.
NH doesn't require any licensure for solid fuel professionals...but, just because the State doesn't say so, that in itself is not a license for folks to go out and install whatever they want however they want. It is also not a coincidence that when a home burns to the ground in New England from a stove...NH homes seem to be more likely to lead the front pages of the papers.
I'm just coming at you from a competitors standpoint Don, but as a licensed and trained professional:
MA Solid Fuel Construction Supervisor #105742
NFI Pellet Specialist: #164362
What are your credentials?