woodstove chimney advice

[Scotty]

Hi yurties,


I'm looking for some advice with my woodstove chimney. I recently put the below post on hearth.com but have gotten limited response and think maybe some yurt-specific advice is ideal. I've seen some threads on here around the drawbacks of the double 90 set up in order to exit high on the wall from a rear-exit stove. I'm pretty averse to punching a new hole in the wall at this point... wondering if anyone who's been living with this set-up has it dialed in and if so how high is your exterior stack?


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I live in a 30' diameter canvas yurt with a Woodstock Fireview as our sole heat source. It's an awesome stove that generally works great... after I clean the chimney. However, I seem to be getting creosote build-up in the chimney at a pretty fast rate. This is my first time living with a woodstove so not really sure what's normal, but I cleaned the chimney in mid-December, for example, and I think it's more than needs it again already after regular-but-not-super-heavy use for that month and a half. We were gone most of that time and had a yurtsitter who I suspect might not have been running the stove quite right, as it smelled pretty smoky inside when we got home, But apart from any operater error issues, I'm wondering if there are some tweaks I could make to the chimney system that would help. I get a little nervous when it smells like smoke inside that I'm slowly poisoning my family!

A month or two after cleaning the chimney I start to get increasing problems with smoke coming into the yurt when reloading the stove or starting a fire. The last couple days have been super windy and that seems to have increased the smoking issues. Apart from the general hassle of cleaning the chimney, it is extra annoying in a yurt because the structure doesn't hold heat very well - in winter by the time the stove is cool enough to clean, the yurt can be freezing inside! We pretty much have the stove going non-stop from late fall to early spring. So anything I can do to extend the cleaning interval would be wonderful.

I'll attach a couple pictures, but basically, single-wall stovepipe comes out the back of the stove, 90's up, runs vertical a few feet, 90s out the wall into a T and then runs up 10 feet of double-wall to a cap. The two things I'm suspecting might be issues:

- Is the 10' main stack (plus the 3' of vertical single wall inside) enough height, given the two 90s and T in the system? If not, how much should I extend it?


- Would it be worth upgrading to single wall pipe for the interior run?

My guess is that I just need to add more height to the chimney, but since that double walled ain't cheap, I thought I'd get some opinions before I try that. Any thoughts on the above, or anything else I might be missing would be greatly appreciated!

BTW, I am using well-seasoned dry wood, mostly doug fir from the property, and am confident that I'm operating the stove and catalytic combustor correctly.

Cheers,
Scott

[Pacific Yurts]

It is very unusual for the chimney to require cleaning that often. Your chimney is the typical height, and if you are only burning seasoned dry wood, it could very likely be the number of ninety degree turns in your piping. I'm not sure if extending the chimney would offset it or not, but a stove specialist might be able to provide that answer. I suspect that eliminating some of the ninety degree bends would also help with this issue. Since your stove is a rear exhaust, you could penetrate through the yurt wall directly behind the stove (lower than typical, but still workable). This would require not only patching the hole higher on the wall, but also lowering your chimney to align your cleanout tee with the pipe coming through the yurt. Installing the stove flashing that low on the wall would also require the use of some silicone caulk to prevent water draining behind the flashing.

Exiting low on the wall could potentially require an extension of the chimney, due to most codes requiring the top of the chimney to be two feet above any portion of the roof within ten feet of it. Hope this helps!

[Jafo]

Adding another section might help. I turned my 90s into using 2 45s and that seemed to help.

Another thing I found is that if you open the stove while the roof it open, it seems to pull smoke out of the stove. Dunno why that is.

Is your wood seasoned?

[Bob Rowlands]

Never had multiple 90s in a stack. Never would either. So I can't address that specific problem from experience.

As has been mentioned, it's a good plan to try and use dry firewood, that is aged at least a year. Keep your wood under cover, if you have a wet environment.

Secondly open the damper(s) before you reload. A good draw should alleviate smoke entering the yurt.

Third, open the stove loading door slowly.

If you have a really tight yurt, open a window or crack the front door when you reload.

And lastly, if the stack is plugging up, just keep after cleaning it out. Until that wood is dried out you WILL have problems with a good burn. Good luck.

[Scotty]

Originally Posted by Pacific Yurts

It is very unusual for the chimney to require cleaning that often. Your chimney is the typical height, and if you are only burning seasoned dry wood, it could very likely be the number of ninety degree turns in your piping. I'm not sure if extending the chimney would offset it or not, but a stove specialist might be able to provide that answer. I suspect that eliminating some of the ninety degree bends would also help with this issue. Since your stove is a rear exhaust, you could penetrate through the yurt wall directly behind the stove (lower than typical, but still workable). This would require not only patching the hole higher on the wall, but also lowering your chimney to align your cleanout tee with the pipe coming through the yurt. Installing the stove flashing that low on the wall would also require the use of some silicone caulk to prevent water draining behind the flashing.

Exiting low on the wall could potentially require an extension of the chimney, due to most codes requiring the top of the chimney to be two feet above any portion of the roof within ten feet of it. Hope this helps!

Thanks for the thoughts Pacific Yurts! Yeah, no doubt going straight out the back would be the best set-up, but I am a bit loathe to punch another hole through the wall at this point! I might try adding a little height to the stack and replacing the interior piping with double-walled first and see where that gets me...

[Scotty]

Originally Posted by Jafo

Adding another section might help. I turned my 90s into using 2 45s and that seemed to help.

Another thing I found is that if you open the stove while the roof it open, it seems to pull smoke out of the stove. Dunno why that is.

Is your wood seasoned?

Yup, my doug fir was seasoned after being split last summer and fall and then stacked . We have hot dry windy summers and early falls here so my understanding is that's plenty of drying time.


How tall is your outside stack?


thanks,

[Jafo]

Originally Posted by Scotty

Yup, my doug fir was seasoned after being split last summer and fall and then stacked . We have hot dry windy summers and early falls here so my understanding is that's plenty of drying time.


How tall is your outside stack?


thanks,

Hmm, I believe it is 4 sections of that double-walled pipe.

Last summer? That might be fine if the trees were already dead, but I would think you would want a second season on anything green.

Well, I don't have much experience with Douglas fir, but for $20 I think you can get a

moisture

meter for wood to see what you have.

Are you getting a lot of smoke out of the chimney?

[Bob Rowlands]

Digressing a bit.

I live in a semi arid climate. The wood I cut and burn from around here is ponderosa pine and scrub oak. If the trees were green/alive when cut, it takes a full year for them to season. You CAN NOT cut it in the fall and expect it to burn well that year. The NEXT year it will be OK. IME two seasons drying yields PERFECT firewood, that doesn't pop at all. It also seasons faster if it is split. I use a gas splitter to do that. My days of Paul Bunyaning the pile are long gone.

Additionally, I've found ponderosa pine sucks as a

heating

wood, in comparison to scrub oak. It burns faster, is prone to popping, and doesn't smell nice like oak. My wife much prefers sitting by an oak fire. imo sitting by a fire of any type wood beats no fire.

As to double wall pipe, that is what I suggest for safety. For a fact though, single wall pipe gives off a massive amount of heat inside the yurt, if the stack runs straight up through the ring. You do need to be >very careful< of single wall pipe location next to wood and canvas.

[Scotty]

Originally Posted by Jafo

Hmm, I believe it is 4 sections of that double-walled pipe.

Last summer? That might be fine if the trees were already dead, but I would think you would want a second season on anything green.

Well, I don't have much experience with Douglas fir, but for $20 I think you can get a

moisture

meter for wood to see what you have.

Are you getting a lot of smoke out of the chimney?

I don't get much visible smoke out the chimney when the catalytic combustor is engaged. I'll get myself a moisture meter...I'm definitely curious after multiple folks questioning one drying season as OK! most of my wood I'm burning this winter was actually felled 2 years ago, but not split and stacked to dry until last spring.


I am curious those of you drying wood multiple seasons what is your process for that? Do you split and stack it uncovered for all that time? Tarp it over the winter between the two drying summers? I know it all depends on your climate but curious what folks are doing.



I built a nice woodshed last fall designed for lots of airflow, with the thought that I could stack wood in there in the spring or early summer and have it ready to burn by fall. It only holds enough wood for one stove season though, so if I have to dry for multiple seasons that gums up that plan... Was hoping to minimize the amount of restacking and tarping needed.


cheers,

[Jafo]

If the wood was felled a couple years ago, then you are probably good (assuming it has dried). I thought you meant it was felled AND split over the summer.

I let the logs sit for a year or two, buck & split them and then stack on pallets then I just cover with old metal roofing. The next season I move them into the (now emptied) open air woodshed as soon as I possibly can so they can dry all summer. That generally does it. I know many people who skip the woodshed part and just use the metal roofing.

With your catalyst engaged, you should not be seeing much creosote I would think, at least that is how it works on my stove. Are you engaging it at the proper temperature? Mine is not supposed to be engaged until the temp gets to 350.

When is the last time you cleaned the catalyst? I think yours is from Woodstock Soapstone company correct? If so, same as mine. You can get replacement catalysts pretty cheap from them.