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Thanks for the info. Attached are the operation and install manuals for our fireplace:
Our fireplace has a regular chimney with an air combustion kit installed. From what I understand, the air combustion kit draws outside air to fuel the fire and then the smoke exits through the chimney. The fireplace was originally set up to burn wood when we moved in (we converted it to gas logs before we ever used wood) and I was told by Lennox that it can be used for wood. Ideally we want to get an insert but right now it's not feasible financially. So we're trying to squeeze as much efficiency out of what we have.
I was told by someone else that I should insulate around the box and the chase and it also mentions it in the install instructions. I believe I read that all insulation must be 1" away from the box but maybe I misread. It was also recommended that I create a horizontal "box" of 2x4s around the chimney pipe just above the box (like 6 to 8' high). I would cover this with plywood or drywall (maintaining at least a 1" gap around the pipe) creating a deck. The the entire deck would be insulated with unfaced insulation to within 2" of the venting. Aluminum tape would be used to seal the firestop to the venting.
I also found the following article on outside air combustion.....any thoughts?
you are right according to that you have a 1" clearance to combustibles. and it doesn't say that you cant insulate so that should be fine. you keep mentioning an insert. are you planning on putting an insert in this unit? if so you could potentially be seriously compromising your safety. at the least if your insurance company finds out they will drop you in a second. there is only one prefab fire place that is ul lised to have one specific insert put in it and your fire place it not that one so there is no way that you can have an insert put in that will meet code.
Around here, any insulation that contacts a combustion vent can only be rock wool- they will fail an inspection here if it's fiberglass, even unfaced. All the inspectors I have asked said the only other acceptable alternative would be to fire-caulk the space which would be very cost-prohibitive. Prepare to itch!
no insulation should contact this vent it calls for a 1" air space doesn't matter if it is combustible or not