Rocket stove in a Yurt

Hello all,

I live in Canada near Quebec City and last Summer I bougth a 32 feets Yurt (14.7 feets at top) Yurt picture. If all things go well, I plan to live in it in winter too. The isolation of it isnt really hight so I need a good stove, about 75-80 000 BTU I already test a pellet stove but wasn't satisfied. I plan to build a rocket stove mass heater.

I start to draw combustion chamber plan with Sketchup for 6 inch system :



- The bricks are fire brick : 1 1/4 x 4 1/2 x 9 so approx 100 - 110 brick

I got 2 questions :
- What is the density of brick I need for the combustion chamber ? Here I can buy Fire brick (medium density 3000 F, 3,21 lbs for 2$ Canadians per brick), or high density brick tested for 2000 F for 4.25 $. Did the medium density brick gonna crack sooner ?

- Did you have an idea of how much BTU a 6 inch rocket mass heater can give ? should I got for a 8 inch system ?

Thanks

Better use insulating firebricks, but for the feed tube and burn tunnel floor. Where high density would last the longest.

Have you read this?

https://permies.com/t/29327/labs/RMH-Tipi

Thanks for the reply.

I just read the 'Fake fire break' post, and the Erica's intervention about appellation of the different kind of break depending on region etc.

So, better to use Dense brick for Feeding and burning core for the abbrasive quality due to wood / ash cleaning tools. The Heat riser brick are not really important, but the Heat riser need insulation for sure. I can get the medium dense insulating brick 1 1/4 thick pretty cheap, and the Heat riser would be isulated with perlite clay-stabilized. With 1 1/4 insulated brick, how many inch of perlite/clay is needed ? did 1 1/2 in Heat riser corner is enougth ?

Considering a "J" feed means hours of tending a fast burning fire... maybe adding new wood every 30 minutes... else consider a batch box rocket - look here: https://permies.com/t/45368/rocket-stoves/member-project
Hope that helps you build it better the first time...

The Batch-box is interesting but I think I will go with J rocket type. Im a seasonal worker working in a tree nursery with a small forest behind with growing trees (lot of different kind, and lot of willow too). I have an easy and cheap acces to wood shaving too as our neighbor are a pruning company.

So if I can burn the wood shaving a vertical loading should be better and adding wood isn't really a problem for me since I will be in the Yurt close to 24h / day.

The Batch-box is maybe a bit more smoky too ?

Hi Sylvain; I think that a J tube is a good way to go. We heat a greenhouse/studio with our rmh . Once its going, we set a timer for 40 minutes, and have no problems. Not having to feed a fire at night is a blessing. In your case living with a J tube will be fun, sitting on your mass poking small sticks in the feed tube to keep a dragon roaring . I think that you will find you burn more split logs than chipps. Adding small amounts of chips to spike up your fire, when you want extra heat. For splitting your wood down to rmh size ,try mounting a tire on your chopping block and standing your wood inside , works very well,and no bending over to pick up your wood! Good luck

Yep, I saw some video on Youtube about it, but splitting wood isn't a problem for me, my parent get 2 huge boiler to make maple sirup and I still splitting the wood about 20 cord of 24 inch and 5 cord of 12 inch for the final boiler. All this wood splitting with a good splitting hammer, we got one too behind a tractor, my father use it because he get old and got some shoulder problem, but I find that too slow and I enjoy splitting with hammer

I already try the Tire things, but I prefer to take a cord with some loop on it, and an elastic so you can bend it easy to fit the size of cutting wood

Some guys used chipps packed in paper or onion bag to feed them stoves, but like you said, but since the feeding tube isn't really big, packaging isn't really worth it.

P.S. - Oh since im a Frenchie's my english isn't perfect sorry if its hard to understand

I draw a 8 inch system with SkechUp, and trying to figure out how to put the thermal mass. The yurt is 32 feet diameter, and I'll place the stove in the middle, with a wall exit. I bougth the book, the 4 dvd, and with a 8 inch system, in the dvd they said we need like 50 linear feet of ducting and when we put an elbow, we introduce 5 feet, so did you think it can work that way ? I fugure to put the majority of the mass near the middle for a bed and maybe a bench too and let the space near the wall for cleaning and other things.

And another question, did the stabilized perlite/clay is strong enough to support the 55 gallons barrel ? or I really need to make a brick structure all around it ? In the second picture, you can see a 2" of perlite/clay under the combustion unit, my plan is the isolate all interior of the finished brick box with it, then put the 55 barrel on, and seal with cub etc. , will it work ?

The exterior 3 Tee's of ducting in the picture one, is an idea of the book to prevent wind from blowing down the flue

Thanks

What you have drawn will make a small area of floor very well heated, but leave most of it completely unheated. I think it would be better to have a single loop that goes (for example) 8' north, then 5' East, then 25' south to the chimney, with only two 90 degree bends. This will make warmth in most directions from the center.

You should also plan to make the chimney as tall as your yurt, or at least 10', so the wind doesn't play tricks on you with fluctuating pressure that can backdraft. The "H" may help with small-scale wind directional changes, but if the whole side of the yurt has high pressure from wind, it will still backdraft.

If you can seal the chimney into the center of the roof, you will get better, more consistent draft and lose less heat to the outside. The chimney should be cool enough to go through it with insulating pipe and flashing.

About the thermal mass yep, Ill try to plan something better, I want to mainly know if the length of ducting and dimension of mass will be ok. For the chimney, an exit in center isn't possible because I got a plexiglas dome that I can open, and I actually have an existing hole in the wall.

The main wind is from ouest, storm wind east and existing wall ducting exit in south south-west, in the picture the door is south-east, so the wind will mainly never come from from upside.

Yesterday I take 2 pictures who easy show the wind effect on snow.

On the West side, a field with some (I plan to add more norway spruce in that line, they grow fast and are really good to block the wind )

I draw a little thing to show how I think the wind affect the Yurt, not sure about how strong will be the wind pressure inside the ducting.

I misunderstood that you were planning on underfloor ducting... probably mixed up your thread with another current one. Heating a bed and bench without going down into the floor or blocking off part of the floor from access does pretty much require a layout like you showed. There may be a layout that gets the desired parts with fewer bends, but it requires knowing how you want to use the interior to come up with something good. So keep trying stuff! Sketchup revisions are free!

Something I would consider is using a half-barrel bell (or two end to end) under the bed to spread out the heating without loops of duct. This would get more heat extraction with less friction in the system. What is your floor construction?

In my first post, I put a link to my yurt design construction plans, etc, that was before I want to have a mass heater inside You can see how the floor is, build in 2x6 bolted and doubled with adjacent piece.

Hum, I maybe get soap stone realy cheap from a guys who worked in a mass stove industries before, if I understand your idea with the half-barrel bell, you suggest to create a larger 'air chamber' under the bed, so the heat of the ducting gonna heat the air in the barrel-bell instead of heating directly stone, less friction for sure, did it will stack more heat than stone ? ill need to read a bit more about it

Look up Matt Walker half-barrel bell, here and on donkey32.proboards.com. He goes over the details of the idea in various places.
Basically, the air enters the bell, slows down, the hottest air rises to the top, and the coolest air sinks to the bottom where the exit is. There are more things to consider, but the big thing is that the heat can spread out and not create friction doing so.
The heat is not stored in the air but there is more internal surface for the air's heat to transfer to the mass.

Can you post more pictures of your yurt, I am thinking of getting a wooden one, that is also 32'. But I am unsure if it will be enough space inside to live in. How do you find yours, would it be enough space for 2 people?

Yurt picture --> follow the link ! Yurt picture

Oh, well I installed my Yurt in end of October 2014, make the floor last winter, than oils the wood in summer etc. So this was my firt winter test I sleep in it for like 3 week and get catch by a nasty winder storm for 2 day long with 160+ km/hours wind with ligthning etc. It was a bit before Christmas, the canvas on the roof was gone, I return to get the manufacturer warranties etc. I solved the problem, but at the moment, nothing else except a pellet stove is in the Yurt. Ill go back to live in it in like 2 week.

I love the Yurt, I like the wood fence in X, im really not an artist, but everyone comment's find it so nice. You know, 32' diameter is pretty big ! its like 800 feet square on floor and you can add mezzanine too if you want more space, on my Sketchup drawing, its like 1000+ feet square where you can stand up + storage for lower side near the roof.

Now its up to you to know if you need more space or no but 2-3 person can easy live in a 1000 feet square space