Whooo hooo!!! I think it's going to work! Rocket heater thrown together in a hurry...mostly it's well below freezing here already, so not many great days for cobbing. I was hoping to get the basic heater up and running to warm up the work space and let me finish the plastering and a bench.
Anyway, just fired it up tonight..lit on first match and got a good roaring draw happening, even though everything is still wet. I'm pretty excited and have finger's crossed that this stove is going to work without too much tweaking. It was fun to actually feel the temperature differences along the system.
The stove is pretty much exactly out of Ianto's book, but sized down a bit for my small yurt. Riser is heavy pipe, 6 1/2" inside diameter, perlite insulation, a smaller sized barrel (30 gal?), two inch gap between barrel top and heat riser top, exhaust is 7 " single wall stovepipe (about 18' in a back-and-forth run to be buried in a bench, then about a 12' vertical exit out the central roof ring), and the burn tunnel / feed tube is recycled brick with CSA a bit smaller than the riser.
Tomorrow will be spent doing some more cobbing on the stove, and starting to get the thermal mass set around the exhaust.
Aesthetically, I love how it throws firelight and shadows up to the yurt ceiling, it's going to make a nice space...
Hi Gretta, I'll post some pics for you for sure, be patient it might be a few weeks before i manage it...I got caught by early winter and some hard weather and things are pretty crazy right now..
Is your yurt open or does it have the two center posts in the trad. mongolian style?? I have the two posts and the central rock tie-down, so the stove has to fit into all of that. No rooms, just open living space in the round with a central hearth.
In Ianto's book he does caution about rocket mass heaters in poorly insulated structures....where there is a lot of air movement and heat loss you might be better served by the radiant heat of a more conventional stove. Probably depends on how insulated your yurt is and what your climate is like. I am leaving the heat barrel un-cobbed to try to maximize radiant output. I can't tell yet if it's going to keep me cozy as I've got thousands of pounds of nearly frozen wet cob in the partly done stove and floor....it's probably going to have to burn for weeks to dry that out and warm it up before I can say I've given it a fair chance. I think it's going to be good though.
Well with this new info i may need to rethink my heating options. When i finish my yurt it will be completly open without the center braces. I live in tennessee, so our winters are rather mild. Im not certain how well it will be insulated. Depends on funds. It is going to be a 16 foot yurt, so rather small. I just really love the idea of the rmh. But i will keep researching. Good luck with the drying. Yi look forward to seeing the ppictures!
-just sharing a little info from Ianto Evans' Book - 'Rocket Mass Heaters' - that I picked up Only On My 3rd Reading, - in trying to build the smallest 'Rocket Stove' that will work for small spaces. - When you substitute a smaller barrel for a 55 gal drum the smaller barrel will HAVE TO radiate the same amount of heat for your "Rocket Stove" to work right, and will end up doing so at a much higher temp !
Success has a Thousand Fathers , Failure is an Orphan
Finally moved into the yurt! (it's been busy here) Last night was the first winter night in it. Temp was about -7F / -20C with a nasty wind.
I've been a bit concerned about RMH perfomance in this context...fairly poor insulation, not much mass in the building, cold weather.
Overnight it held heat better than my microcabin...the cabin would definitely have froze hard overnight, there was no ice in the kitchen in the yurt, though the snow on the floor by the door didn't melt. So that was nice. I am missing the quick flashy radiant heat of the cabin stove just for warming up in the morning. I have the entire barrel exposed to maximize radiant heat and right now it seems just adequate but quite a bit slower than a woodstove. So last night was not as cold as the cabin, and the morning wasn't as cozy...which is sort of what you might expect.
I am expecting performance to improve though, as I move in and start continually heating the place. Much of the bench still hasn't dried / cured as it has been frozen solid most of november. The floor was frozen too. I think after a week of soaking heat into the place the coziness factor will jump up quite a bit. I hope so. Also slightly more moderate temps would make a big difference.
I'll write again to update. I'm still pretty confident that this is going to be good!
ps yurt is much more insulated than a tent or tipi, with about 1 3/4 " of wool felt insulation. It is still much lighter and less insulated than a house.
in the spring I will be building my own Yurt/Ger. This week I stumbled upon cheaper insulation quite by accident! Next door a fellow is renting part of the farmyard to store his roofing materials and trailer. He has 20' wide Rubber (10' folded) and 10' wide felt. In a quick reply to me, the price per ft is so much cheaper buying it this way, that you could fold it 4x over to make the price up for regular felt!
So, check out flat roofing supply center or find a flat roofer and buy some of of them. My other idea for thicker insulation is folding over regular bubble wrap, bubbles into each other. I use that now for my windows and it works great. Use wide packing tape for the ends of the bubble wrap to keep the air in and moisture out. Might also check out Uhaul, they sell super insulated blankets for moving, sometimes they come on sale.
Thanks for the update on the RMH in a Yurt, since I live in a camper now the info is excellent.