NFPA211 Insulation thickness?

[offroadaudio]

I'm doing a new install and have some options to consider here.
The prime objective is to get a SS liner into a masonry chimney with 8 x 8 tiles.
My options are:
1. a well respected professional, who I know will do an excellent job - but will be expensive. His specs include breaking out the clay tiles so that he can get "enough"
insulation around the liner. Is there a spec? I've seen 1" and 1/2" - I think I can get 1/2" and 6" SS down this perfectly straight flue.
2. Downsize to 5.5" SS if the 6" will not fit. The flue is 32' tall, so I'm worried about lack of draft - and I can fit a damper if too much draft.
3. Use rigid liner and no insulation.
4. use pour - in insulation in any of the above choices.

Any knowledge / comments appreciated.

Thanks.

 

[begreen]

The insulation is 1/2" but it wraps all the way around the pipe and thus adds at least 1" to the total diameter. With 32' of stack, I'd be inclined to go with 5.5" liner. Is this an interior or exterior flue? Is it a straight clean shot down with no large mortar globs at the tile joints?

 

[offroadaudio]

It's exterior.
I was leaning toward the 5.5" also. I even e mailed Hearthstone and asked.
Of course they can't approve the downsize because of code - BUT they said check with your local dealers and installers for
feedback on how such an installation might work.

So, any advantage to going with rigid over flex in 5.5"?

 

[begreen]

Ask BroBart about his setup. My thoughts are to go rigid if possible for it's thicker, smoother walls. But there are lots of good flex systems out there too if that's what works best for you. If you end up going with 6" be sure to add a damper. 30' is the max chimney height for the Hearthstone Heritage.

 

[offroadaudio]

I like the rigid also for the thickness.
Thanks for the info.

'Frank

 

[oconnor]

Sitting here in front of my poorly drafting Jotul Kennebec, 5"flex, 25 ft, inside flue - do what needs doing to get the 6" down the flue - rigid and insulated. I've read that you will lose 15% equivilant flow using flex instead of rigid. As well, it is easier to reduce draft later (more restricitive cap, close primary air more/earlier), but tricky to get more draft once it is installed.

I am of course projecting my woes on your situation, but I'd give $500 to have had it done right the 1st time, instead of fussing with overly small splits and watching the stove temp drop off if I shut the primary 1/4 inch to much. Now I'm waiting for my installer to come back and reinstall to meet code. Money TBD.