Older Jotul 118 install ... 5" (or 6") Single wall versus double wall? damper?

[black_sab]

I'm finally installing my 1980s Jotul 118 (w/5") opening.

Saw a few threads regarding single/double wall and still not sure what to use .... since draft/length of pipe seemed to be a factor in the decision. Trying to save some $$$...

durock w/1" wall spacing is in place behind the stove and extends up the wall/roof rafters to reduce clearance.

I'll have between 5 and 6' vertical from the output of the stove and where the black stove pipe will terminate into the roof support. From there I calculated I'd need ~10-11'+ of triple wall above the roof.... so total run will be around 15-17' which exceeds (meets) the manuals recommendations.

I've got the 5-6" adapter on hand...and right now my proposed install will consist of the adapter connected straight to the stove followed by a 6" 90 degree elbow and then straight up to the support box.

It seems single wall will suffice?

I may get two 36" lengths and toss a damper in between, but haven't done the research yet.

 

[begreen]

The pre-EPA 118 is not too draft sensitive. It should be fine with that setup with single wall. A butterfly damper is not a bad idea. Make sure that the wall shield is open at the top and bottom by at least 1" to allow the free flow of air behind it.

 

[black_sab]

The pre-EPA 118 is not too draft sensitive. It should be fine with that setup with single wall. A butterfly damper is not a bad idea. Make sure that the wall shield is open at the top and bottom by at least 1" to allow the free flow of air behind it.

Thanks for the quick reply. I'll plan on adding the damper, can't hurt.

I used 1" diameter electrical conduit cut to a shade over 1" as my spacers (fastened using 1" washers for some extra clamping pressure) so there should be free movement of air behind the shield. Not sure if this will fly with the inspector but that's what i had on hand, easy enough to swap them out.

One thing that the NFPA spec states for clearance reduction is that the spacer fasteners should NOT be directly behind the stove, which makes a 5' wide piece sort of 'flap' around a bit. Is guess it depends on the building inspector as to whether he will stick hard and fast to the rules, but I'd like to have at least another couple of spacers behind the stove to make it a bit more rigid.

 

[begreen]

To be a legitimate NFPA wall shield it must be open at the top and bottom by at least an inch.
https://www.hearth.com/talk/threads/wood-stove-wall-clearances-primer.147785/

 

[black_sab]

To be a legitimate NFPA wall shield it must be open at the top and bottom by at least an inch.
https://www.hearth.com/talk/threads/wood-stove-wall-clearances-primer.147785/

Yep...it's off the floor a bit over 1.25", and plenty more than than up top.

 

[begreen]

Sounds good. The stove should be no closer than 12" to the wall behind the wall shield, though single wall pipe requires 18" clearance. As long as the hearth is adequate, the pipe has the proper clearances, and the chimney is correct, the inspector should be happy.

 

[black_sab]

Sounds good. The stove should be no closer than 12" to the wall behind the wall shield, though single wall pipe requires 18" clearance. As long as the hearth is adequate, the pipe has the proper clearances, and the chimney is correct, the inspector should be happy.

Could you point to the detail in the NFPA where 18" is spec'd out with single wall?

 

[begreen]

Double wall stove pipe is 6" to the wall and 9" to the ceiling

 

[black_sab]

View attachment 186471

Double wall stove pipe is 6" to the wall and 9" to the ceiling

thanks, saved me a bunch of rework and maybe an extra roof hole.. . I'l have to pull my hearth out a bit from the wall.

What about the junction between the roof box support and the roof rafters? Do I need to make sure that the closest point (where the pipe meets the box) is also 18" away on the diagonal perpendicular to the roof rafters?

I drew a crude diagram...

 

[begreen]

Technically I think yes, but it looks like the chimney support box is going to effectively shield it so I don't think this will be an issue.