Rear Flue Exit through Yurt Wall

blueridge

New Member
Mar 4, 2020
2
Virginia
Hello!
I have a question about taking a rear exit flue through a yurt wall. The stove is a Jotul F100. It has the capability of top or rear; the collar is currently in the rear and for aesthetics is our preference. Every picture I have seen for yurts uses a top exit then an elbow to go out through the wall (through thimble and flashing) and into the T. My question is: Can I instead run my stove pipe straight out through the wall to the T? Would I need to slope that run slightly up? Diagram below (credit Pacific Yurts) showing in red what I am talking about. Any considerations to keep in mind, or something I haven't thought about that makes this less common (or not done at all)?
Thanks for your time!

rear exit.jpg
 

begreen

Mooderator
Staff member
Nov 18, 2005
81,729
South Puget Sound, WA
Horizontal runs should be kept as short as possible, especially with a short chimney. For this reason, we installed from the top. It also made it easier to do through the wall passage. We came off the stove with a 45 and offset to reduce the resistance of a 90º elbow. On this Morso, the config works reasonably well. There can be a little smoke spillage with outdoor temps above 45ºF if one is not careful, but not bad. Top-down starts work well in this case.
Yurt stove.jpg
Plan on adding another 3 ft to the chimney to take it up to 12' (could do 3-48" lengths). The Jotul F100 manual says:
Chimneys shorter than 14 feet (4.27 m) may not provide adequate draft.

We wrapped this up at 12' just after dusk.
outside_yurt2web.jpg
 
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jetsam

Minister of Fire
Dec 12, 2015
4,693
Long Island, NY
youtu.be
The more vertical rise you can get before your wall penetration, the better. The less 90s, the better. So while your diagram will probably work, Bergen's example will smoke you out less often on mild days. If you really want to make the stove happy, consider a straight vertical shot through the roof. (Not sure what a "yurt" is, so no idea if it's multilevel or what the roof is made of.)
 
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begreen

Mooderator
Staff member
Nov 18, 2005
81,729
South Puget Sound, WA
The more vertical rise you can get before your wall penetration, the better. The less 90s, the better. So while your diagram will probably work, Bergen's example will smoke you out less often on mild days. If you really want to make the stove happy, consider a straight vertical shot through the roof. (Not sure what a "yurt" is, so no idea if it's multilevel or what the roof is made of.)
A yurt is an adaptation of a nomadic home, still used in Mongolia by herders. Roof penetration is not recommended due to sealing issues. The roof is a heavyweight coated fabric.
yurt1.jpg
 

begreen

Mooderator
Staff member
Nov 18, 2005
81,729
South Puget Sound, WA
You might want to consider a larger stove if this will be used in winter. Even with the insulation kit, these yurts don't hold heat that well. A larger stove will also afford a longer time between reloads.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
20,931
central pa
The more vertical rise you can get before your wall penetration, the better. The less 90s, the better. So while your diagram will probably work, Bergen's example will smoke you out less often on mild days. If you really want to make the stove happy, consider a straight vertical shot through the roof. (Not sure what a "yurt" is, so no idea if it's multilevel or what the roof is made of.)
Straight out the back of the stove eliminates a 90. The only reason I don't like to do it that way it because it limits your options if you want to change stoves.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
81,729
South Puget Sound, WA
With a short chimney and a shallow firebox stove, I wouldn't do this. Especially in a mild climate zone. That is why the 45s instead of a 90.
 

blueridge

New Member
Mar 4, 2020
2
Virginia
Thank you all for your input! I appreciate it.

A little additional info that I omitted in the initial post in an effort to be concise: I have a mini-split as my primary heat source (and a/c), but given the poor insulation it can't keep up when outside temps get below freezing. So the F100 is to work in conjunction with it during the winter and shoulder months. (The yurt is rented spring-fall, and only used on weekends in the winter by wife and I.) So I am fine with its size.

The manual says not to exceed horizontal runs over 36"; with the straight shot out the back it should be less than 24" (rear clearance to the wall is 8", and clearance of the chimney to the exterior is only 2" with triple wall). As mentioned, it would eliminate the 90, but I don't know which factor takes priority: the elimination of the 90 or the initial "up" of the top exit. Which setup would draw better and keep smoke out of the yurt on start-up?

I am not overly attached to one way or the other and will change to top exit if the odds of success are better. Once I cut a hole in the wall, it's there for good.

Thank you all again!
 

begreen

Mooderator
Staff member
Nov 18, 2005
81,729
South Puget Sound, WA
Oh, that is an interesting twist. A good minisplit should work well far below 32º.

Like bholler said, the downside of a rear exit like this is that one is locked into the stove's rear vent height.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,133
Northern NH
My pure speculation is a horizontal run directly out of the stove is an invitation to having a tough time getting the stove started. A fully exposed chimney already introduces a tough starting condition to begin with. My guess is a short vertical outlet starts to create a bit of draft when the stove is initially lit while a horizontal run does not leading to smoke being puffed out the air vents. Once the stack is hot its not an issue. My guess is you may need to buy a torch to encourage a draft in cold stove more often.
 

moresnow

Minister of Fire
Jan 13, 2015
1,106
Iowa
No different than installing a pipe straight up and out. Put it where the setup can be used for a larger stove right off the bat! Why limit your future options. Worth a thought perhaps.
 

peakbagger

Minister of Fire
Jul 11, 2008
5,133
Northern NH
No different than installing a pipe straight up and out. Put it where the setup can be used for a larger stove right off the bat! Why limit your future options. Worth a thought perhaps.
Out of curiosity it that an opinion or do you have a basis for this?
 

moresnow

Minister of Fire
Jan 13, 2015
1,106
Iowa
basis for this?
Quite simply. Common sense. If you are going to install a new pipe setup, do it in a fashion that does not limit you to the one stove model you currently have in mind. I'd venture a guess that out of all the stove users represented here, many have changed stove model after the original install. @peakbagger if I misunderstood your question fill me in. It happens;) Carry on!
 

peakbagger

Minister of Fire
Jul 11, 2008
5,133
Northern NH
You appeared to be commenting on my speculation that a short vertical pipe run up out of the top of the stove before making a horizontal offset was somewhat better than a straight horizontal run out of the stove to vertical pipe. You appeared to support the opposite. I was asking what your basis for that opinion was>
 

Jafo

Member
Dec 24, 2009
139
Northern NY
I just want to mention for others who may read this in the future that with most of the major yurt manufacturers, the odds are you will void your roof warranty if you try to pipe straight through the roof fabric. That is why they provide a through-the-wall kit. Most of the big manufacturers provide a 15 year roof warranty, which is nothing to sneeze at.

My preference for mine was through the wall, from the top. Here is a pic of mine right after I installed it. Afterwards, I changed it to two 45s which did help:
1583458570367.png


By the way, I hope this isn't spammy or anything, but I recommended @blueridge come here with these questions after he asked about them over at my forum. You all have helped me so many times here, this is clearly the best place for him to ask any questions about wood stoves!