RMH in a Tipi

And because it's related to the vestibule, here's the next topic:

Ozan and liner
The ozan and liner of the tipi are currently going through a few experiments. Miles and I have chatted about the function of these features in the winter tipi, and I have made some changes in the tipi based on our chats.

Function: The tipi liner is an indoor addition to the tipi for colder weather draft diversion. It's a piece of fabric that hangs from the inside of the tipi, acting as an extra layer to the exterior tipi canvas. Without the liner, like during the hot summers, draft can enter the tipi along the ground since the exterior canvas does not make contact with the ground. This draft is also necessary to feed the open fire in traditional tipi use. During the colder months, a liner is used to stop or ease the draft that comes in along the ground. The liner starts typically at either 6' or 9' high (ours is 6'), and runs along the inside of the tipi poles, and makes contact with the ground. Draft can still enter the tipi through the gap at the ground below the exterior canvas, and then it hits the liner and goes up along the tipi wall, instead of towards the centre of the tipi, directly towards the living space. With the liner, the tipi still gets necessary draft and good air flow, it just does not flow directly at the home-dwellers.

The ozan is like a ceiling. It's a piece of fabric that caps-off the living space of the tipi, slowing the travel of heat up and out of the tipi. Its edges meet the top of the liner, creating a closed fabric cell within the tipi. The overall air flow is: cool draft enters the tipi along the ground and directly flows up along the outside the 'cell' that the liner and ozan make; the liner and ozan contain warm air for the living space. In our tipi at Wheaton Labs, our heat source does not need a path for the smoke to escape (other than the vertical exhaust pipe), so we are able to have an ozan that completely caps off the ceiling (most ozans are not 'full' ozans, but provide partial coverage). Also, with there being enough draft that comes in through the permeable canvas walls in order to feed the RMH's fire, our practice for the past two winters has been to close the gap between the exterior canvas and the ground with tarp. So, the tarp along the ground outside, plus the ozan and liner making a closed cell for the living space, means that this tipi is more draft-free, and more insulated than most.


A few weeks ago Miles wrote in the forum, asking if the back wall of the RMH could function as a liner so that we could raise our 6'liner up higher to succesfully meet the ozan. At the time of his suggestion, the liner was installed to meet the ground, as is the traditional design, but its height only came up a few inches higher than the back of the RMH bench. This idea is very useful to us since our liner does not meet the ozan, and there has been a big gap between those two features all winter this year. Luckily it has not been extremely cold yet, so the extra draft that was coming in was not in dire need of a fix. Last year when the weather was very cold, Tony and Emliy used a series of blankets to bridge this gap. I would like to try both options for making a 'cell' in the tipi: 1) Miles' idea to just raise the 6' liner up to meet the ozan, letting the back of the RMH bench act as the continuation of the liner to the ground, and 2) Tony and Emily's use of the 6' liner installed commonly to meet the ground, and then hang a series of blankets to bridge the gap between the low liner and the high ozan.

My thoughts on idea 1 are: It's great! The intentional liner is easier to install than blankets as a liner, and has far less gaps and places for draft to get in than a collage of blankets. This works well with Erica's suggestion about easing jetstream-like draft in a home: start insulating from the top of the house, down. I know we're not in a house, but it's good advice that I'd like to try in the tipi. The downside, however, was pointed out to me by Derick: The bottom of the RMH bench is of drystacked stone. The liner is not touching the ground, and the bench serving as the continuation of the liner to the ground might not be appropriate since the draft can now enter through the gaps through the stones, as well as cool the RMH exhaust pipe that runs through the bench. The pipe, to my understanding, is mostly encased in cob, but it were installed on top of the draystack, so the bottom of the pipes may be exposed to this cool air.

My thoughts on idea 2 are: Well, it might do-well to still have that liner touching the ground. So, let's try idea one first, and then compare it to idea 2. If idea 2 works better, then I can ask Paul if he'd be willing to invest in a 9' liner that would meet the ozan.


Yesterday I installed the liner according to the idea 1 plan. I'll live with it this way for at least a week, then switch to the set-up for idea 2.

Thoughts, suggestions, opinions about the tipi ozan and liner?

liner & vestibule around the bed

RMH & liner of segmented heights & ozan & vestibule

pillowy ceiling

the stain on the ozan is from incoming rain dripping from the poles.

Since the liner is not exposed to outside weather and doesn't have to shed serious rain, I don't see that it would be a problem to just sew another 3' of canvas to the bottom edge to make it 9' tall.

Yes.
Sometimes I forget the more reasonable options.

I'm guessing it would take 2-3 days to do a good job of hand-sewing all the details in. That's some nice introspective winter work.

Olenka, one of the things that I have seen done is a pole run horizontally from above the door, out to any given length, supported outside of the lodge, by two poles that form a bipod set of legs. Just above the door, at a height of your choice, the pole comes through where the "stick laces" connect the cover, and is supported by a short pole at a right angle to it, which is attached to the two upright tipi poles on either side of the door. A canvas is then thrown over the horizontal pole to form a sort of triangular pup tent that is attached to the ground and as tight up against the tipi cover as possible. This can also have a canvas door flap at the front.
Sorry for not having a sketch. Does that make sense? Sort of like this.

In fact, now that I look at that picture I am wondering if the horizontal pole couldn't be run all across the inside of the lodge and attach to one of the poles at the back. Creating a ridge pole that might help support the ozan and provide a place to hang things if you wanted to. Not sure , just throwing that out there.


I guess I missed the part about the bottom of the bench not being sealed so that air would go through the rocks and cool it. Next time (summer) you all are making some cob could that be sealed up or does it have to be open for the bench to function?

You are doing great stuff there Olenka ! Love the innovation.

I thought with original tipis the flaps at the top each had a pole.. you situate each flap according to wind direction etc. Like so its not funneling wind down inside or making a sail of itself. And in real icky weather its flapped shut much as possible just to barely let out smoke and not let in rain etc.
I could be wrong or maybe that interferes with the RMH chimney?

Please forgive me if I missed the discussion... but is the 'core' made out of cast cement?

Or maybe someone can point me in the direction of the discussion of that RMH core.

Thanks all

No, it's not cement. Cement couldn't take the heat generated in a rocket stove core. I've seen cores cast from fireclay mixed with various lightening substances, like perlite. This one might have been part of the "shippable core" work and I think they were using some fancy materials for that. . .

Hopefully somebody else can give more information.

Jami,

On page 1 of this thread there's a bit of a staggered account of the core. It was first made from "Erica's amazing new goo", and then later replaced with Paul's wood box style of core. The thread for the wood box style core is quite detailed, worth a look.

paul wheaton wrote:

The first core was using Erica's amazing new goo. Only we think that putting it in a place where there is frost before it has completely cured was not a good idea.

Emily Aaston wrote:Tony and I spent the better portion of the last week building a new core for the tipi. We used Paul's new wooden box style and posted a lot of pictures on his wooden box style thread: wood box style.

Miles,

I like your vestibule suggestion. It keeps well with the design of the tipi, both functionally and aesthetically. And the idea with the pole going across the diameter of the tipi is good. And vertical and hanging storage is always looking to get swallowed up in that space, so another place to hang things is great. My one concern about this reminds me of a bigger issue that I recently started to ponder:

I think the current poles are getting a little saggy. I am not sure what the poles were like to start, or how flexible tipi poles usually are, but I think these poles might be in need of some love or replacement. I need to take a sharper eye to the state of the poles and compare them to other sources out there, but I think these guys are on the rot.

kadence,

We don't use the smoke flaps only because there is no smoke in the tipi, as all the exhaust routes through the exhaust pipes and out at the crow's nest. Are you suggesting that using the smoke flaps would be beneficial for helping the RMH to function, airflow-wise? Or maybe the horizontal pole that would support the vestibule might interfere with the ability to use the smoke flaps, or even keep them shut?

Here is a picture of the top of our tipi, smoke flaps (with poles) in the closed position.

It looks like there would be good clearance (gap) for the horizontal pole to come through, and the flaps can be tied down so they form around the horizontal pole appropriately without leaving a gaping hole for draft. This added detail could be a place for moisture to collect in the detail, but I think it would be minimal and worth the compromise to have a vestibule of this kind.

Thanks for letting me know. I was sure I had just missed that bit along the way....

a token from Emily.
i found it in the wood pile!

Here are some lifestyle photos! This was taken in November. Derick and I had a section of the bench dedicated to craft/library/instruments.

For future tipi dwellers- I highly suggest getting a Missoula Public Library card as soon as you arrive!

It's been warm.
Here's a western conifer seed bug silhouette seen through the tipi canvas.

Ok, time for some more discussion!

Re-routing the RMH exhaust
Over the holidays Paul and Jocelyn had Ernie and Erica Wisner over for a visit. Of course, rocket mass heater talk and doing ensued. Among all the ideas exchanged that visit, one of them was Paul's want to make the RMH in the Base Camp house even easier to use than was the original design. So, they pondered up a solution that makes the system friendly for both the experienced RMH practitioner and the new learner alike. See this thread or more details on this design: https://permies.com/t/44064/rocket-stoves/Base-Camp-house-RMH-route#347869. Overall, the vertical exhaust going right by the barrel = Paul current favourite solution to make an RMH very very simple to use.

Paul now also wants to consider this kind of design re-route for the tipi. If this place is going to host many guests and a mix of people of different RMH experience, then we should consider making this system easier to use. This would mean that we go to the drawing board and come-up with different exhaust route possibilities and discuss a number of possible design changes.

I am a little weary of this idea. It's hard to want to change what is already a very good design. The RMH in the tipi is the first that I have ever used, and the first that I have lived with. I have been told that it is very finicky and might require some extra coaching in order to get it going, however this has not been the case. Perhaps it is the effect of the warning causing more caution than intended, but Derick and I found this system to work very well and with little trial. And when there was smoke-back, it always felt like a necessary experience to go through in order to learn how to run the system well. Furthermore, smoke-back in this setting is not detrimental to the space- it is a tipi, a home that is designed to have smoke traveling up and out anyways. And to consider changing the system so that it's even easier to use, but less efficient seems like it's not worth the compromise. During the cold days of winter, this home could probably use some super efficient rockety goodness.

Also, this RMH, with its current, original design, is a good posterchild for what Wheaton Labs stands for: a place were working the edge brings discoveries in efficient living.


What do you think about the idea to reroute the tipi's RMH vertical exhaust? Do you have questions? Opinions?

I am sorry that my writing about this aspect of the tipi was overladen with my opinion. I encourage all suggestions to be posted despite my advertised bias. Let's discuss.

Here is a picture that was posted early on in this thread (on page 1) by Emily. It is the exhaust pipe that runs through the bed part of the bench in the tipi.

And here is a picture of the exhaust and clean-out at the end of the completed cob bench.

I do not think the concerns expressed in the podcast about not recognising the barrel as part of a wood stove are valid for the tipi. The inexperienced user fire start is another issue. Your post indicates it is not that bad. do you have to preheat the vertical pipe when the mass is cold? It looks easy to do from the klean out.

My observation from the pictures is that you have heat shielding by the barrel but no sign of overheating at the vertical flue. I think improving the alignment of the vertical flue to exit through the smoke flaps with an insulated segment at the top that the smoke flaps can close around is the best aesthetic arrangement.

I like the suggestion of the external vestibule. There should be more poles where seedling trees shoot up but can not compete with older trees. A white tarp would do for the fabrick for the rest of the winter.

Olenka, after extended use, the poles will start to bow inward. Is that what you are seeing? I do not think they are rotting, just bowing under the weight of the canvas. Try grabbing hold of each pole and rotating them 180 degrees. This may have to be done every once in a while. This may also be very hard to do with all of the weight and the rope tied around them. So perhaps on a nicer day this spring or summer you may have to take the canvas off, or at least role it all back to the lifting pole, then rotate the poles.

Did you all get the tipi books yet? I am hoping that they will help with many of the user questions that are coming up.

Miles! It arrived! Thank you.
I just started reading it last night. I have a few books on the go right now, but this one just made my top list.

The added bonus of this book is that it is written biographically- one of my favourite reads! Thank you for sending it along. It is the first book that we have here specifically about tipi living. I am excited to learn from Warren's winter experiences.

About the poles: there is definitely a sag to them, and they have no been moved since their initial erection a year ago. I will see to a twist for all of them. And if that's the case, I think I might as well take the whole canvas cover off, and replace the tipi cover at the same time. (We are thinking of switching-out the current tipi with our other, less-used one.) It is very difficult to twist the poles at this time, because, as you had mentioned, there is currently too much weight on them.

Hans,

No heating up of the vertical pipe when the mass is cold. But then again, of the different ways to deal with smokeback, I prefer the more proactive route: prime the pump slowly, really stand by and make sure my fuel is burning well and with proper chimney direction before I walk away. It is the slower way, but it works. I think Emily mentioned heating up the exhaust with a blow torch for the really cold days, but this winter has not been nearly as cold as last.... yet.

I mentioned the exhaust exiting through the smoke flaps at a previous meeting, however the question of how to support the pipe from the exit from the mass to the smoke hole came up. The pipe is heavy. At least in it's current arrangement. It used to drop to the ground on a regular basis when we first moved it- the drystone part of the bench that was directly under it had fallen away. I have since built-up a larger drystone support for it (seen in the picture of the exhaust & cleanout). The diagonal that the pipe would have to take through the tipi would also take up more living space than its current route. Perhaps there are flexible pipe options? Do you know how it's done with a woodstove? From the images hat I've seen, it seems that the woodstove is typically installed directly under the smoke flap opening.

evening RMH tipi kitchen

just a teapot enjoying some cajun tunes on the tipi RMH.

A dancing teapot!

Olenka: You are a hundred times better off than the fellows I used to call on in Fort Kent Maine. They were using a wood stove made of the same blue steel as the stove pipe. They had no experience and wold not listen to the advice of the old timer on who's land the were living.

You might consider just using a swiveling elbow at the top like you have at the bottom to direct the final segment to the smoke flaps.

Why isn't it's shadow rocking as well?

Valerie Dawnstar wrote:Why isn't it's shadow rocking as well?

My educated guess is that this is caused by a combination of two things.

1) Physics. The angle of light casting the shadow very closely matches the direction of movement. Shadows are only two dimensional. The movement is in the "depth" dimension which a shadow can only represent by an increase or decrease in size as the object moves closer/further to/from the light source. With such a small amount of movement, this change in size is very small.

2) Video compression. A high amount of video compression which "throws away" "unneeded" minute details in areas of the picture which have no (little) change over time. Essentially the shadow part and any other still portion of the image is very similar to a still photo. Only the areas with significant movement require bits of information to be constantly updated. In video compression this can drastically reduce file size but at the cost of reduced detail.

It still does feel quite strange and unnatural to look at though.

You got it, David. My usual preference is to capture the kettle so that it's spout is visible, but the shadow's stillness in contrast to the animated mother was too good to give up!

afternoon tipi

f

And update about the Ozan and Liner:

It's been quite warm. It is definitely warmer in the tipi these days, more specifically, these past 2 weeks. I think that installing the ozan and liner helped to make things warmer by keeping the draft down, but more than that the weather has been at play here. It has been warm. The nightly low only makes it to about freezing. The days reach about 60 F (15 C). Earlier I had mentioned that I would try 2 different arrangements for the ozan and liner, but now I'm thinking I'd just like to leave it as is for now. It takes a while to rearrange the ozan and liner, especially as a single occupant, so I'm going to leave it be. I will note that the idea to bring the liner up to the ozan and use the bench as the lower part of the liner = a great idea! In future, a good piece of fabric to extend the liner to the ground might be of good use just to slow any air that comes through the drystone base. I've thought about extending some cob down and into the crevasses of the dry, but I think it might be useful to keep the drystone as is, with all its lovely gaps. This, imagine, is a gateway for evening summer breezes.

split

This weekend Jason and I made a little hunt for some sewing supplies. The tipi needs some love, mending in a few places.
We were directed to purchase a sewing awl.
This little wonder of a tool comes with a spool of sturdy thread, and a wee wrench that doubles as a screw driver.

our sewing awl!

Tipi Entrance Mend

The first thing to mend is the entrance. It ripped up the one side, and the picture below was taken after I had cut an identical "rip" on the other side. I could have just mended the tear with a patch and kept the door in it's original shape, however Paul had expressed that a taller doorway would be nice. The initial tear seemed to be going in the direction of his thought, so I'm running with it. Also, I fear that a patch may be a place that will collect water. My idea is to leave the cutting to just these two areas, make a hem around the new shape for the door, but keep all the original fabric there (instead of cutting it off after hemming). I'd like for this mend to be able to be undone in the case that it is found to not be the ideal door shape.

I do foresee one possible problem with making the door taller: The pull on the canvas is no longer the same with the new shape. Derick thinks that the taller the door gets, the winder it needs to get in order to maintain ideal tension on the canvas. Since this tipi is already used and needs mending in a few places, I figure it's ok to experiment with a new door shape.