Old fire place chase for air space around double wall

[rdrcr56]

I removed a heatilator fireplace insert and am building an alcove. My question is, can I run the double wall chimney pipe up through the center of the old chase for the fireplace? The inside diameter of the old steel chase is 13" and extends 6" above the old existing chimney. Duravent states a spec of 2" to combustibles and this would give me 2-1/2" to the side of the chase and then the closest combustible would be the framing around the ceiling support box.

 

[MountainStoveGuy]

yep, as long as you maintian your 2" airspace you will be fine. Now, is this steel chase the outside layer of the SL300 chimney that was on the heatilator? If thats the case, i have heard of chimney pipe sweating when inclosed in anoter pipe... why not take the old pipe out and start from scratch? thats whay your basicly doing anyway....

 

[rdrcr56]

The old chase is open at the top where it enters the old spark arrestor. I was going to run the chimney pipe up and then cut an 8 in. hole in the top plate, run the chimney through that to stabalize the top and then put a storm collar on and silicone the collar to the plate.

 

[MountainStoveGuy]

Heck, i just realized who this is.. i need more coffie. Did you get your hearthpad figured out? That plan sounds like a plan. You can also stablize the chimney with the simposon part number 9463 roof support. It would bolt down nicley on top of the chimney.
You can look at the catalog here if you didnt grab one...
(broken link removed to http://www.duravent.com/catalogs/dtech/index.htm)
Im off today.. so you wont find me at the shop. You are welcome to call me, i will pm you the number if you like.

 

[rdrcr56]

Thanks alot, I apppreciate all the help