Still obsessing about chimney setup

[jeffee]

Thanks again to all who have given me thoughts and advice,

I'm still second guessing myself in the final days preceding my Jotul 118 cb and prefab chimney installation. My latest concern is that of how important is it to have most of the chimney inside. My current plan (pasted from my earlier thread) is:

900 or 1000 sq. foot log house, 1 1/2 stories, open layout, not very tight and not insulated on walls (only on roof).
Chimney will go straight up.
Total planned height of chimney (measured from top of stove / bottom of stovepipe to top of chimney) would be 19’ 4” give or take a few inches.
About 10 1/2 feet of the chimney would be above roofline (necessary because it’s not coming up at the peak of the roof, and the roof is steep 45 degree)
I get a good breeze often from the North, the same side of the roof that the chimney is on (the gable sides of the house are east and west).

What I'm considering is trying somehow (it would not be ideal inside the house, nor easy, because of the clearances and hearth size issues ...) positioning the stove further into the room such that it would have to stick out of the roof 5 or 6 feet instead of the 10 1/2 feet if I go with the original plan. Again it would still be a total vent length of 19' 4" give or take. As a side note if I go with the revised plan I would be able to reach the chimney from the [shorter and not as steep] roof of the small addition, to make cleaning / inspecting easier.

From the interior, the original plan works SO much better, but I want as close to an ideal system as possible, as I've been reading up on woodheat.org.
Any of you care to advise me?

 

[JohnnyBravo]

if you have a flat interior celing than it does not mater where you put the stove from a preformance stand point. the attic is concidered a cold zone. howver it it is a vaulte ceiling than keepin the extra lenth in a warm zone would probably help. cleaning would be an issue on a 12/12 roof with 10' sticking out. it may even require 2 braces back to the roof, lots to take apart come cleaning time. also a cold long run of chimney may require cleaning more often. still interior placement is important and is something you will be dealing with on a daily bases, you may only clean your chimney 1-2 times per year, you can always add a slip joint to clean from below.

 

[jeffee]

Thanks JB for your response. The upper 1/2 story is loft (my bedroom) so it's all heated. I'm not sure what a slip joint is ....

Yes this is another tough call for me ....

Thanks again

 

[webbie]

Given an insulated chimney (metal), I don't think you will have to worry about it either way. Your chimney sounds like it will be fine. Even an exterior insulated chimney (mostly straight up) is vastly superior to most chimneys out there.

 

[jeffee]

Craig,
Thanks, that means a lot. So you think the added benefit of plan B wouldn't be significant?

 

[JohnnyBravo]

i think that the interior placement is most important and if Craig feels it will draft fine i would belive him, he has much more experience than me. a slip joint is a pice of black stove pipe directly above the stove that will slip up and down so you can get a brush in from the bottom. it seems a bit messy but a ladder job up there seems a bit sketchy.

 

[jeffee]

Yes I've tried to consider the inspecting/cleaning aspect of the installation too. I'd like to be able to check it easily. There's also the chimney cap to consider -- that even if I could open it from the bottom that wouldn't get me access to the cap. If I'm doing my figuring correctly, with 10 1/2 feet of chimney above roof, then if the top section is 4 feet, I *may* be able to reach the top section at 6 1/2 feet to take it off. I'm not sure how heavy it is. I'm thinking I could angle a ladder from the ground so it sits flush on the roof and reach it that way.

Being a newbie is hard, but I know I am going to LOVE my stove ...

 

[KP Matt]

I have a clean-out "T" on my old Jotul 118. I don't think I could bend the rods enough to feed them up the chimney that way, but aren't there more flexible rods available?

The side or rear flue exit probably doesn't perform as well as the top exit in the new 118s... but that's just my guess.

 

[KeithO]

Why not add a 45 degree once you clear the ceiling (I'm still not clear that there is a ceiling) and run the pipe toward the roof peak parallel to the trusses and then do a second 45 degree to come out the roof close to the peak. That way you only need about 3-4 ft above the roof line and you avoid chimney damage caused by roof avalanches impacting the chimney (there should only be a foot or so of accumulation from the peak, so very little snow weight). You will not save much pipe if any, but will reduce the succeptibility to damage significantly.

For function (particularly starting a cold stove), I recommend keeping the chimney inside the heated envelope. If you are able to space the stove adequately, then using stove pipe does add to the effective heat produced by the stove. The output of my Morso is definitely reduced because of the double wall stovepipe.

 

[jeffee]

Thanks very much for the suggestions and ideas.

In either case I'd be going through the ceiling which goes up to a loft (my bedroom)- the ceiling is made of 1 1/2" boards.
The 45 / 45 idea is cool, but I think I'd rather keep it simple, and it would be quite a bit more expensive (the 45 kit and more chimney) and maybe too much pipe for my bedroom. I'm curious to know if that trade off would even be advantageous -- introducing angles into the equation.

I didn't think about the chimney vulnerability from roof avalanches -- wow, have you experienced this sort of damage before, or know of people who have?

I sure would like to be able to have easy cold start ups, as I would like flexibility -- sometimes it'll be fired up constantly, and other times I may be gone for a while. I also want to avoid stuff like reverse draft into the house when the stove isn't fired up, etc.

It will be a telescoping double wall stove pipe, so I think I can disconnect that to peek up occasionally. It sure would be nice to not have to jump through hoops to get access to inspect and clean the chimney.

Again, thanks for reading this and advising me. Your ideas are REALLY helpful.

 

[KeithO]

Class A is 2" clearance to combustibles, so you could keep the pipe quite close to the rafters. The double wall may not penetrate any kind of construction, so the class A has to start at the ceiling. Bear in mind that with the insulation in the Class A, you could probably touch the outside of the pipe when the stove is running, so you will only get a little gentle heat off it. It may pay you to try to order the class A from Menards. It is still $57/3ft which is about a 1/3 of the typical market price. The regular black double wall would be about 8 ft high (stove is about 2 ft), leaving about 11ft to the top of the roof. This would need 4lengths of class A going straight up and probably 5 lengths if you do the double 45 degree trick. Of course you add 2 elbows too, so something like $120-150 more in cost.

If you get a reasonable amount of snow, you had better believe that your chimney can get damaged if it is near the eves. It is of course particularly bad if you get several feet of wet snow, especially if you have several freeze thaw cycles to make things icy. Of course with present winter weather unpredictability, who knows... Maybe we will need beach towels and cooler boxes....

 

[jeffee]

Thanks Keith,
The chimney will be Superpro, and a hearth store/dealer will be doing the install. The 45 kit is exPENSIVE! Plus there's something very attractive about keeping it simple straight up, not to mention it is best for draft, but yes I'm trying to factor in the benefit of keeping more of the chimney warm. I really would like the 'perfect' installation but I guess that really doesn't exist in my situation. I do take Craig's guidance as a very good thing though.

 

[Gooserider]

The chances of "avalanche damage" can be reduced by installing V-shaped "crickets" or snow diverters above the pipe. This is a small board structure a few inches tall that acts to divide any slides so that they pass to either side of the chimney, not through it...

I would definitely make provision to clean the chimney from the bottom, far safer / easier to clean that way, especially when the weather is nasty. It doesn't always let you get the cap, but you might not need to reach it, especially not with every cleaning.

Gooserider

 

[jeffee]

Thanks for the info!
What else would you recommend to make provision for cleaning from the bottom? The current plan is a telescoping double wall stove pipe, straight up, and I was assuming that I would disconnect this to clean from the bottom. I will certainly ask the dealer about installing a diverter on the roof. At 10 1/2 feet about roof one set of bracing should be ok, right?

 

[Gooserider]

If you have a rear exit stove, you should exit into a "T" with the cap on the bottom, and clean by removing the cap and pushing the brush up through the opening. If you have a top exit stove, then the slip pipe is the way to go.

In terms of bracing, that will depend on the specs for your particular brand of pipe, but I suspect that 10.5' will need two sets of braces. I think the spec is somewheres around one set of braces for each 4' of height, but don't quote me on that. More braces won't hurt, so it won't hurt to have them.

Gooserider