Rocket stove mass heater in a ger, need advice.

Hi!

Pretty new to the forums, although I've been reading what's been happening on here for years now. I'm planning to move back into our yurt year long starting next spring. We've lived in it for 3 seasons (fall, winter and spring) before, and loved it. We were located in Northern Ontario, so it was a full winter.

We have a traditional 19ft Mongolian Ger (Yurt). The only problem in the winter was that it was so frigid in the morning. We were thinking of solutions about this, and a rocket stove mass heater came up as the ideal situation, especially now with a baby with us. I don't worry about me under 9 wool blankets, but my kid will probably have none of that (by kicking the blankets) and freeze stiff.

We'll most likely be moving in Nova Scotia in the spring on a farm, temporarily move into a trailer, set up the prospector's tent and build the RSMH. I would LOVE to have an earthen floor, and have the rsmh bulge out of the ground in the middle of it, but my partner is worried about space. I think it'll be fine in the middle by making a bench/bed radius. Do you think it's feasible to finish it in time for winter? We have plans for one, but it's for a larger home - how do I adapt it to a yurt space?

To those who have any shred of advice on any of this, many thanks.

It is also possible to build a RMH which is mostly under the floor, taking no more space than the feed tube and barrel. Here are some people who did this 5 years ago, except they put the feed outside their yurt. Not sure I'd recommend that, but you can decide.

https://permies.com/t/5937/rocket-stoves/rocket-mass-floor-heater-finally

You would want to build up from grade and have excellent drainage, and insulation under the floor/mass.

i feel like there was someone in Cali that did a very similar thing to what is being asked, but i can seem to find any info on it.


anyone know what im talking about?


edit:
a floor appeared! by fishermansdaughter, on Flickr

more can be found here: https://www.flickr.com/photos/fishermansdaughter/page5

hope this helps.

Yes, that's the same writer, and the same project, as the permies forum thread mentioned above discusses.

This is great!

Do you think it would be wise to start with under the floor heating? I think I've read that you shouldn't start with that. What about too much drag, putting out the fire?

Is it possible to just make the mass mostly in the middle, with a pipe radius for the pipe going out, and not the whole floor? I guess this way, the whole yurt would be on a mound, making rainfall less of an issue.

Surrounding that could be plants with deep roots and good compost on the outside diameter (good compost can hold up to 900% of its weight in water, currently asking the partner to find his source of information)..

That would take a boat load of clay. Is it the same percentages for an earthen floor as for cob, i.e. 75% sand, 25% clay - or does it need structural fibers in there as well?

Oh boy. Lots to learn!

Rachel, check out this rmh in a small earthbag home.

A fun project, and lots of good information. However, I do want to caution viewers about one point: they talk about learning that a 3:1 ratio, that is, a heat riser height 3 times the system diameter, is best. This is a rocket cooking stove practice, not a RMH practice, and contradicts research done many times over. You will often for fitting sticks want a J-tube feed tube height (from burn tunnel floor) about 2 x system diameter, or 12" for a 6" system or 16" for an 8"system. The heat riser should then be 3 to 4 x the feed tube or 36"/48" to 48"/64" high.
If your system has a good final chimney which drafts well, you can do with a shorter heat riser, but if anything else in the system is marginal, a short riser will not have the power to compensate.

Briefly,

I don't know a lot about yurts, but I don't see why a RSMH could not be incorporated into your build.

There is a teepee at Wheaton Labs heated by a RSMH that has been through more than one winter, and had some modifications. One important one is that to get the exhaust to draw after the horizontal duct went all over everywhere, (heating the arc shaped bench at the perimeter of the teepee, then under part of the floor) is to bring the exhaust duct past the heat source as it rises to go out. This concept was discussed at the pyronaut's event last October. Apparently at least 2 of the experienced rocket stove gurus had come to this innovation independently of one another.

How long it will take to build, and can you finish it in one season, starting in spring and ready for winter depends on many things. It can be done, but there are SO MANY variables. Experience level of builders, when the ground thaws enough to begin, how prepared you are when spring time gives you the go ahead, what random things happen that need to be redone, reworked. How much help you have, how available your material are, and so on.

You are wise to begin planning now.

If you do decide to put the heating ducts under the floor, which I think is a good idea, remember that mattresses and rugs and such have been scorched by the temperatures attained. Your heating ducts would need to be well covered, and / or well designed so as not to get hot spots on your floor!

I read some problems with under floor heat in the 12' yurt from fisherman's girl project posting - She mentioned that it was often too hot. And I could think that it might be dangerous to have a raging hot barrel almost floor level with tiny humans around, or with drunken stumbles.

When we lived in it, we had a thin-walled stove, fabricated by the same people/community that made the yurt - definitely not a safe stove. It had a cut-out design on the front, a little feed door on a flimsy piece of metal. It was just the best - we would make a little fire and the yurt would heat up to the point of being too hot in about 20 minutes. Even with not keeping any mass heat, we only used about one and a half to two full cord of wood (rotting birch, not even the best quality).

I just can't imagine having this great big barrel of radiating heat inside on a coolish fall evening and be comfortable.

SO - I can't find any examples, but I think we'd like to make the feed and barrel outside, in a different building, and only have the piping go through the floor. The place it would be would have to be well covered and not catching runoff water from the yurt. The more we thought about it, the more it was appealing - this place could be turned into a sauna at times, a drying room for wet clothes (either from washing or from winter activities), a place for the wood... I do think it's nuts, but we're crazy enough to try it.

I want to make something comfortable that we love for the long run. I don't want to regret building a whole floor and rocket stove that is too hot to live in most of the time.

If we need a bit more heat inside the yurt, it would be easy to install something that makes a little bit more heat. I mean, I'll have to cook inside the yurt anyways. By finding a good cooking solution, it might be enough.

One important one is that to get the exhaust to draw after the horizontal duct went all over everywhere, (heating the arc shaped bench at the perimeter of the teepee, then under part of the floor) is to bring the exhaust duct past the heat source as it rises to go out. This concept was discussed at the pyronaut's event last October. Apparently at least 2 of the experienced rocket stove gurus had come to this innovation independently of one another.

This is good information to know. Thanks!

Depending on your summer weather, you might want to design cooking capabilities into the building where you house your rocket stove, so that you don't heat your house up with summer food preparation and preservation. It might turn out to make your ger more roomy and habitable to have this second room. Is it possible to make it so that you can go between the two without going outside? I mean a sort of two room ger, connected gers? Maybe the kitchen could be in the RMH room, (and the firewood too?) freeing space in the main ger for other functions.

My cousin and her husband built a ger with an upstairs. I visited it one time, and I remember many things about that visit. It was the night before the attack on the world trade center. My memories of that visit are not about the architecture! We had talked about the (US) Constitution, how our society had gone astray, the current bureaucracy & corpratocracy, how the bill of rights had been usurped, how the USA was becoming more like a third world country, all that. My cousin's husband said "it is all still there, waiting for us, the 200 year old dreams of a workable democracy, and a framework on which to base it......" We all know what happened next. As I said there are many details of their beautiful ger that I don't remember.


I can't remember how they heat it, but they must, they live in maine. It was built on a wooden platform, raised up off the ground. There was a wrap around walkway/deck all the way around the perimeter of the ger. Inside, it had a beautiful wooden floor. They used the space under the walk way for storing all kind of things out of the weather. They also had a staircase in the center and a usable loft room. Very cushy! A family of four lived in comfort.

Wish I could offer more on this topic, but I have no other ger experience. Good luck with your project!

How stable is the weather where you are building? Does it get cold and stay cold, do you have cold nights and warm days, does it fluctuate without warning?

The more you can rely on needing heat consistently, the more a larger remote system will make sense. The California yurt has a huge firebox and barrel, and is probably considerably oversized for the space; thus it easily gets too hot. You could make a smaller system inside your yurt and be able to control the fire closely to fine-tune heat delivery. About half of the heat from a standard RMH is released from the barrel as instant radiation, and half is stored in the mass for timed release.

Thekla McDaniels

Depending on your summer weather, you might want to design cooking capabilities into the building where you house your rocket stove, so that you don't heat your house up with summer food preparation and preservation. It might turn out to make your ger more roomy and habitable to have this second room. Is it possible to make it so that you can go between the two without going outside? I mean a sort of two room ger, connected gers? Maybe the kitchen could be in the RMH room, (and the firewood too?) freeing space in the main ger for other functions.

That's what I was thinking - summer kitchen in with the RMH room. And I love the idea of having just *a bit* more space in a yurt - going down from a duplex to a yurt means that we'll be more cosy, but we still have lots to learn regarding space layout/organization. I think we'd be able to go from room to room if we would enclose both entrances together - I can't see myslef cutting into the structural wall and be comfortable doing it.

Glenn Herbert

How stable is the weather where you are building? Does it get cold and stay cold, do you have cold nights and warm days, does it fluctuate without warning?

The more you can rely on needing heat consistently, the more a larger remote system will make sense. The California yurt has a huge firebox and barrel, and is probably considerably oversized for the space; thus it easily gets too hot. You could make a smaller system inside your yurt and be able to control the fire closely to fine-tune heat delivery. About half of the heat from a standard RMH is released from the barrel as instant radiation, and half is stored in the mass for timed release.

This is the thing. I don't necessarily know. We'd be moving there in spring.

We've lived in it in zone 2b, we're currently living in zone 2a and we're moving to zone 5b.

When we lived a winter in it in zone 2b, we needed heat pretty consistently in the winter BUT a tiny fire in an airy stove did the trick. It got cold in the night, and we'd be freezing out of our blankets for 10 minutes before the tiny fire warmed up the whole place so much that we'd have to open the door.

As for the conversation we've had with the land owners of the property we'd be moving onto, it does get cold, but there's just a few nights of -20 in the winter. And the winter is 4 months. Where we lived in it, the winter was 6 months, and there was 2-3 weeks straight of -20 weather and less during the nights.

It's really the longer-term heat I'm looking for. The night heat. Just enough so that my boy's toes don't fall off in the night if he decides to kick off his sheets. There would be winter cooking in the yurt, and that happens multiple times a day, everyday, so I think we'd still be alright for overall heat, if we have under floor heating to take off the general cold.

Thinking about the little stove we had (not saying that it's anything like a RMH), the instant heat PLUS stored heat would have been too much - in zone 2b.

If you can join the entrances of the main yurt and the RMH enclosure, and you would want to be cooking frequently in the main yurt, I could see having the RMH semi-remote. You would want to build a batch box style so you could load it and let it burn, instead of the frequent tending a J-tube would need. The batch box does reportedly require a good chimney at the end, so what you might do is run the mass ducting from the barrel looping under the main floor and back, then rising beside the barrel to the termination. This would allow you to put in a bypass for easier starting, and also to run the RMH for cooking in the summer without heating the floor. If the terrain allows, putting the RMH room a step or two down from the main floor would make drafting easier (less downward run for the ducting). It would also let the entry be lower than floor level, reducing cold drafts.

Glenn Herbert wrote:If you can join the entrances of the main yurt and the RMH enclosure, and you would want to be cooking frequently in the main yurt, I could see having the RMH semi-remote. You would want to build a batch box style so you could load it and let it burn, instead of the frequent tending a J-tube would need. The batch box does reportedly require a good chimney at the end, so what you might do is run the mass ducting from the barrel looping under the main floor and back, then rising beside the barrel to the termination. This would allow you to put in a bypass for easier starting, and also to run the RMH for cooking in the summer without heating the floor. If the terrain allows, putting the RMH room a step or two down from the main floor would make drafting easier (less downward run for the ducting). It would also let the entry be lower than floor level, reducing cold drafts.

Thank you so much for this. I'll do some more research on batch boxes and bypasses - it seems like that's exactly what we would need.

I like that the more we talk about it, thinking about this or that detail, the more it becomes a plan that I can envision easily. 'll be sure to document the whole process once we get to building it.

The soil on the property is clay rich, and the sand available would be beach sand. We'll be visiting the property in the coming weeks, so I'll be able to know more then.

Rachel Dee wrote:

I like that the more we talk about it, thinking about this or that detail, the more it becomes a plan that I can envision easily. 'll be sure to document the whole process once we get to building it.

The soil on the property is clay rich, and the sand available would be beach sand. We'll be visiting the property in the coming weeks, so I'll be able to know more then.

Rachel, that is exactly how it is supposed to work! One of the things we've lost (temporarily I hope) is the ability to discuss our ideas with experienced people of varying opinions and wisdom to help our idea become workable and practical plans.

And about the clay soil and beach sand, do you know how to go about testing for clay content, and is the beach sand sharp sand or is it polished and rounded sand, and do you know about making test batches.

I guess I just should have asked if you have built with cob in the past. It is wonderful stuff and I love it but it's another topic to discuss if you have very little experience with it!

Thekla McDaniels wrote:

And about the clay soil and beach sand, do you know how to go about testing for clay content, and is the beach sand sharp sand or is it polished and rounded sand, and do you know about making test batches.

I guess I just should have asked if you have built with cob in the past. It is wonderful stuff and I love it but it's another topic to discuss if you have very little experience with it!

No, absolute zero experience with cob. I've read up a lot about it.

For testing for clay content, I was going to dig, and if I can make a ball, I would think there would be enough clay. For sand, I don't know just yet - which is one of the reasons we'll go visit shortly. It's better if the sand's polished and rounded, I assume?

For making test batches, I was thinking that I could make fist-sized balls and dry them- try it out with different ratios - and see what I have as a result; it stays together, cracks, crumbles, or whatnot. I also heard that when making a ball, if it's dropped from standing position and stays together, it's close to being good.

Polished, rounded sand is the worst possible aggregate. Imagine building something with marbles - if not for the glue, it would fall down instantly. Sharp, angular sand is the best, and is standard mason's sand.

Making a ball is one test, but one of the least useful aside from crude go/no go estimation. A more helpful test is to make a sausage or snake of the material. If you can stretch it or bend it double without it breaking, it is most likely excellent clay. The more you can bend a snake over your finger without significant cracking, the better quality the clay is.

Rachel, The two books I know of that explain in detail how to test the soil for clay content are "The Hand Sculpted House" by Ianto Evans (and others), and "Build Your Own Earth Oven" by Kiko Denzer. I used these books when I had no experience and they were helpful. There is a cob forum on Permies https://permies.com/forums/f-76/cob where people are talking all about cob.

Maybe even someone in your area! I don't really know where you are, but maybe you said Nova Scotia? There was someone talking about Vermont (USA) in the cob forum, but I guess that is still a long ways. At the very least there are good cob threads to read and others to discuss cob.

To make test cob, make your trial batches. Using a "brick" shaped mould, make and dry a brick from each test. If you make your mould 10 inches or 10 centimeters, it's easy to see the % shrinkage. You really don't want any shrinkage at all, but you also don't want it to be crumbly. Too crumbly, not enough clay. Shrinkage, too much clay.

Anyway there is also a regional forum. Here is the link https://permies.com/forums/f-132/ontario to the Ontario bunch, but it's not limited to Ontario, and the other close one is eastern USA.

It might be a good place to contact "local" people.

I had another thought, this one about your baby. My babies slept with me til they were about 1 year old. (easier nursing, no one has to wake up, get up, etc). The did not get a chance to kick the covers off! I know there are some people who have a "family bed" and everyone sleeps together.... It would certainly easy your mind about the little ones being warm enough, and people must have done it that way for hundreds of thousands of generations. It must be a viable option!

Anyway, check out the cob forum and the "locals" in the regional forum, and good for you for starting early!

Thekla McDaniels wrote:Rachel, The two books I know of that explain in detail how to test the soil for clay content are "The Hand Sculpted House" by Ianto Evans (and others), and "Build Your Own Earth Oven" by Kiko Denzer. I used these books when I had no experience and they were helpful. There is a cob forum on Permies https://permies.com/forums/f-76/cob where people are talking all about cob.

As I'll only be moving to NS in the spring, I'll get these books to read more about it, and go over to the forum for specifics. Good book recommendations are always welcome, especially right before a very cold winter.

Thekla McDaniels wrote: I had another thought, this one about your baby. My babies slept with me til they were about 1 year old. (easier nursing, no one has to wake up, get up, etc). The did not get a chance to kick the covers off! I know there are some people who have a "family bed" and everyone sleeps together.... It would certainly easy your mind about the little ones being warm enough, and people must have done it that way for hundreds of thousands of generations. It must be a viable option!

Oh yes, family sleeping is amazing. I never had a sleepless night so far (he's 9 months). That being said, he'll be 14-15 months when we'll be moving. As much as I love sleeping with him, I don't know if I won't just be interrupting his sleeping. I just want to be prepared, have one less worry in case he runs wild quietly in the yurt before we wake up. He's already walking, so I wouldn't be surprised.

Glenn Herbert wrote: Polished, rounded sand is the worst possible aggregate. Imagine building something with marbles - if not for the glue, it would fall down instantly. Sharp, angular sand is the best, and is standard mason's sand.

That makes a lot of sense. I guess I'll have to go by feeling, and take a sample back to a microscope to see what's what.

if the sand is sharp you will probably be able to see the sharpness of it, unless it is very fine. Also, in a cob mix, you will be able to hear the sand grains rubbing against each other...

get some sand and clay from anywhere you can and begin to play with it! See if you can tell the difference between sharp and rounded sands, and notice that grains of sand can vary a lot in size.

do some tests as described in the books, make some test batches just to see the differences between too much and not enough clay.

This way, when you show up at your building site next spring, it won't be the first time you're doing those steps, you'll be familiar with the procedures the feel and look of things. You'll be miles (kilometers?) ahead next spring.

Maybe you and your little one could play mud games together!

Also plan on building something cob before you are doing your mixes for structure and interior and life support things.

Just fyi, I live with ancient sand, fairly fine too. I have a microscope to look at soil micro organisms, and I've seen my sand. It is not particularly sharp or angular, but I was able to build with it.