block-off for new install

[MrGriz]

Getting ready for the install of my new Osburn 2200 insert (going out to purchase this weekend if everything goes to plan) and i've got a question about the install.

I am installing in an existing masonry fireplace. I know that I need to install a block-off when I remove the existing damper from the flue. I have asked several local dealers and the ones who actually confirmed that I need a blockoff (not everyone said it was necessary) told me to "just jam some kaowool, or something like that in there". Is this good enough, or should I fabricate a metal plate and seal it to the existing flue? I guess another way to ask that question is how critical is it that that block-off is air tight?

 

[elkimmeg]

If you have read enough of my responses to this question then you know what my answer is I hope other will respond to confirm what I think or debate it

 

[MrGriz]

Elk,
how is the plate sealed to the existing opening? High temp sealant, cement, welded...
also, would you recommend insulating the inside of the existing fireplace before putting the insert in? I have the room and don't know if this is a good idea, or just a waste of time.
Thanks for your input.

 

[elkimmeg]

common RTV caulk can be used aroung the perimeter seal ITs ok to do this in two or more overlapping pieces but sheet metal screwed and rtv caulked
Tapcons into the bricks or motar seams will hold it in place. Just enough to hold it in place and RTV caulk the space between the pipe and the plate gasket / stove/ furnace caulk cement.
K wool is a good idea surounding the liner and the block off plate Hot flame and I did this with his install common sgalvanised sheet metal can be bought at Home Crapo
we made acardboard template first we oversized the liner cut and cut out another square witha closed tollerance to the vent pipe hole with one slit to the cutout cauled the crap out of it and sheet metal screwed it into place. then gasket cement the remaining space next to the liner and plate. I cut the damper out witha 4.5" grinder and a thin metal cutting wheel for the liner to pass threw

To answer you insulation the fire box I don't know how effective this will be with a convection insert? Would the reflective value of shinny galvanived sheet metal there be better?

this is a good topic for debate

 

[MrGriz]

Thanks Elk...The plate and RTV sounds easy enough and I understand the need.

As for the insulation in the existing fireplace, I'm not sure if it pays or not. My thought was that it would help to trap the radiant heat from the back, sides and top of the insert and re-direct it back into the living space. On the other hand, would it cause the insert to overheat? Could I slow a full load of wood enough to keep the temp down?

If I do decide to experiment with insulating the fireplace, what would be teh material of choice? Something just to insulate, or something to insulate and reflect the heat?

 

[elkimmeg]

what about sheets of galvanized sheet metal spaced off the bricks reflective value is there air space might prevent heat biuld up and promote air movement
I guessing here

 

[BrotherBart]

I would hold off on insulating around the insert. I did that in the reconfiguration of my pre-EPA insert and it contributed to huge surface temperatures when I ran it the first time it was loaded up after the reconfig.

I would advise running it awhile with out it and try it later. Find out how the stove runs "au natural" and then tinker with it if you want to.