Advantage/Disadvantage of factory heat shield and single or double wall stove pipe.

[mhrischuk]

Laying out the floor plan for my Hearthstone Equinox. It looks like the best situation for my space is to use the rear heat shield so I can get to 8" from the wall. This is with a single wall stove pipe. I can go 2" closer (6") if I go with double wall. I don't want the stove 17"+ inches from the wall or the hearth will be way too far out and become a tripping hazard. I also believe the farther it is from the wall the better the circulation but I don't have a lot to work with since it's a walking path.

Does the double wall stove pipe have any effect on the flue? Is it better? Since it's not an insulated pipe I would think it would not have much if any effect at all. Most likely I'll stick with the single wall.

 

[firefighterjake]

Circulation: You don't need a whole lot of space to have the heat circulate . . . this is a non-factor.

Double wall pipe: Honestly I think you could go with either . . . some folks say the double wall pipe is better at maintaining the flue temps since you have less heat loss in single wall pipe . . . which could be good or bad depending on your goal. Single wall folks could say that they like scavenging some heat off the single wall pipe for the home, whereas double wall advocates could say they like having the closer clearances and get most of their heat from the stove. Neither are wrong. Double wall pipe may not be insulated . . . but the gap between the two walls has air in it . . . and air is a good insulator.

 

[mhrischuk]

Well I don't know how the heat shield fastens to the stove and the possibility of adding the blower option is there. If I went with the closest to the wall option (6"), would it be an issue with the heat shield if I had to do some maintenance?

 

[mhrischuk]

OK I just talked to engineering at Hearthstone. They said it is serviceable at the 6" wall clearance.
I imagine the double wall stove pipe is a bit more expensive.

 

[begreen]

Yes, double-wall is a bit more expensive, but it is a one time investment. In this case the operative issue is performance. Double-wall pipe helps reduce heat loss, keeping the flue gases hotter. The stove will draft better and the flue will stay a bit cleaner if the flue gases are warmer. If the total flue height is marginal, then double-wall is the way to go. What do you estimate the total flue height will be? Will the pipe be going straight up?

 

[mhrischuk]

Working on that now. Standard ceiling height with a 30" high stove and probably 2" of hearth is 65" to the ceiling.
One story house with an intersecting hip roof. It's 95" from the ceiling to the peak of the high hip. So from the top of the stove to the peak is 160".... just over 13 ft. I'm not sure if I need the extra 2 feet yet.
I will require to 45's under the roof to get to a higher exit on the main hip.

This picture is a head on. The stove will be inside, centered between the two sliding doors.

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Inside the attic it'll come out of the joists in the space next to the wire where the light is shining. Then it will 45 back and to the right, going up through the roof.

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This picture shows two possible exit locations. I think the higher one is better. This will give me a shorter exposed chimney.
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[begreen]

13 feet is the minimum. Definitely go with double-wall connector pipe. Note, the maximum offset with class A pipe is 30 degrees.

 

[mhrischuk]

Looks like I'll have to do a mock up with 30 deg elbows.

Looks like I may have a problem with clearance since the pipe enters the attic close to the roof. The roof looks like 30 deg (7/12) pitch.

On edit... this is getting nuts. One 30 elbow is $400

It looks like I may have to do the dance under the ceiling. Ugly but not much choice.

 

[begreen]

Yes, 8" pipe is expensive. However, that should be the price for 2 - 30 deg elbows. They come in an offset kit.
http://www.dynamitebuys.com/store/cart.php?m=product_detail&p=5821

 

[mhrischuk]

Thanks. This is ugly. The main problem is I can't go straight up or it will cut into the rain valley of the roof.

I have to shift it to the right and away from the wall.

Unfortunately the entrance to the ceiling is close to the wall AND close to the roof. The roof is 30 deg from horizontal so a 30 deg elbow will not do much I don't believe. Maybe won't even fit up there between the two elbows and roof.

I'm going to punch a pinhole at the exact location up through the drywall ceiling and look up top what I'm dealing with.

 

[begreen]

I can appreciate that. This was my concern when you first posted here. I was wondering where the stove would go because of the venting. Is there space for the stove in the corner of the room, to the right of the home theater system?

 

[mhrischuk]

Yes I could rearrange the room some but it would take away too much seating options for the home theater viewing.

It's going here in this spot, just need to optimize the flue.

What about putting the chimney where I want it and running a 90 closer to the ceiling?

Or two 45's up to it?

How come it's ok for a 45 or 90 inside but not in the chimney?

Also read the chimney elbow is not allowed in a joist area. Well the I would need one right there between the ceiling joists and the rafters.

Right now I'm looking at shifting the stove over to the side a foot or so to see if it's enough to clear the roof valley. I have a left side load Equinox. I can shift the stove way over to the right. It only needs 3'1/2" of hearth on that side. That would allow a large hearth area on the left side where the door is and room to put some wood. Chimney straight up.

Checking now.

 

[begreen]

Given the short stack, a pair of 45's with an offset would draft better.

 

[mhrischuk]

Looks like two choices.

I can have the stove slightly offset to the left and go out with a 90 into the outside screen room. Install the chimney in the ceiling of the screen room. I need the slight shift of the stove like 6" to the left to clear the screen room intersecting wall.

Or install the chimney inside pretty much anywhere using two 45's... ugly


This website is having issues right now.

 

[begreen]

Will the screen room option allow for a greater overall flue height? The pipe could be chased with a service door for the cleanout. It will be the more expensive route, given the parts required.

 

[mhrischuk]

About the same height but I can add some height anyway.

Can you elaborate on yur suggestion. I don't know how the cleanout works. Is it just a round cap at the chimney connection?

 

[Highbeam]

You may have misread a spec. The single wall pipe must be 18" from the wall, not 8". Double wall pipe can be 6" from the wall.

Double wall interior pipe is much better. It is stainless steel inside and will last much longer, like as long as the rest of the chimney. The draft will be better too and you'll need every bit of draft you can get with all those bends.

 

[mhrischuk]

You may have misread a spec. The single wall pipe must be 18" from the wall, not 8". Double wall pipe can be 6" from the wall.

Double wall interior pipe is much better. It is stainless steel inside and will last much longer, like as long as the rest of the chimney. The draft will be better too and you'll need every bit of draft you can get with all those bends.

Equinox manual says the back of the stove can be 8" from the wall when using the factory heat shield and single wall 8" stove pipe.. I will take your advice and go double wall.

 

[begreen]

I think the point is that if you used single-wall that close to the wall, it too would need heat shielding.

As soon as you penetrate the room barrier you need to switch to class A pipe. That means a class A thimble into a tee. The bottom of the tee has a round cap that is removable for cleaning.

As for the screen room, how would you be coming out of the stove, straight to the wall thimble or up to a 90 and then to the thimble? The reason for the question is that each 90 degree turns reduces draft. Figure about 3ft height loss for each 90, or about 6 ft more pipe for a total of about 18ft. This may be a tall exterior pipe, depending on the height of the screen room ceiling at that point.

 

[mhrischuk]

I don't want a cell phone tower .

I can't believe this valley is such a pain.

Is a 90 out and a 90 up considered two 90's? in otherwords the stove pipe goes up, 90 into the chimney and then the flue gasses have to go up... another 90.

This stove can be rear vented straight out and then up like a hearth.

Can the exterior chimney be inside of a screen room?

 

[begreen]

Yes, that is 2 90's. You have to switch to class A as soon as you penetrate the room envelope, so yes, that would put exterior pipe in the screen room which is ok, but it should be chased or at least safely screened to prevent the possibility of accidental burns.

 

[mhrischuk]

What about converting to rear exit on the stove and go straight out the wall then up? Is that one 90? Is that allowed without a fireplace?

 

[begreen]

Yes, that is one 90. The stove must have hearth floor protection regardless of connection. It is allowed, with the caveat that it will be fixed at a permanent height based on the stove.

 

[mhrischuk]

Yes I edited. I meant is it ok to rear exit into a combustible wall with a thimble, directly from the stove, not being a fireplace with all the brick.

 

[oldspark]

You may have misread a spec. The single wall pipe must be 18" from the wall, not 8". Double wall pipe can be 6" from the wall.

Double wall interior pipe is much better. It is stainless steel inside and will last much longer, like as long as the rest of the chimney. The draft will be better too and you'll need every bit of draft you can get with all those bends.

Good single wall pipe will last over 30 years, mine still looks new, if you have only a few feet of pipe I doubt you will see much of a difference in draft, the clearance would be the big advantge IMHO.