Mass heater for tiny house?

Hello! I am going to have a tiny house built on a trailer in MA. I'm aware that a mass heater would create the challenge of excess weight, but I'd be willing to invest in a stronger trailer because I like the idea of heating with renewable energy and simple woodstoves seem like too much work.

Is there such a possibility as a mass heater with a very small footprint (around 24x24)? My tiny house will be 146 square feet not including the loft, but the main living space will be separated by a wall to allow for more efficient heating. The main part will be 96 square feet not including the loft.

I have seen the cabin stove masonry heater at firespeaking.com as well as the Dragon Heaters rocket stoves. Those still seem too big. I liked Kiko Denzer's masonry heater hat and Max Edleson's suggestions on a hat with masonry support, but I read that these may not burn clean and can also run a hazard of cracks in the masonry.

I've attached my initial tiny house floorplan. The square with an "x" is designated for a stove.

I have no building / technical skills and would hire someone for designing and building this. I'm also open to suggestions on people in my area who may be able to help me with this project.

Thank you!

Hi...
I don't know if this will help but I had seen this a while ago and I will share it with you. This is a video for a rocket stove core that uses fire proof materials so it is probably a bit lighter than just clay and cement.
http://youtu.be/7ANMXGrxgnE
I know when I am ready to create a rocket stove I will follow these instructions for the core.
Good Luck, Kirsten

That looks promising. Thank you Kirsten!

Depending on how well your house is insulated, you may be able to use a 4" or 5" RMH system, as even a 6" will provide more heat at one time than you would be able to stand in such a small space. While the combustion core needs to be refractory ceramic material (and can be very lightweight), you need real mass to store heat... but that mass doesn't have to be all masonry. You could run the exhaust through a water tank that would absorb heat very effectively and re-radiate it over time. The tank could be drained if you want to move. This would not be practical for living on the road, but if that was what you were doing, you would call it an RV or trailer, not a tiny home.

Note that RMH systems smaller than 6" are reported to be tricky and require experienced construction to get working well.

(Dragon Heaters' 4" RMH core would be a good base to build on, as they have done the homework to make sure their units will work well when properly installed. And the 4" unit is not terribly expensive compared to the 6" or 8", likely less than you would have to pay someone to build the core onsite.)

That's a cool idea. I love it! I love that the water can be drained if ever needed. I will definitely look into it.

Good to see you have reached out to ask about small footprint stoves. One idea is to look at what is called a Shepherds' stove. I hope this pic cut and pasts OK (if not just google shepherds stoves). They are designed for tents so it would seem to fit the bill. I'm a contractor and I pull a lot of equipment on trailers all the time. Don't load up your trailer - you don't want to do that. It's a false sense of mobility. The alternative is to build a cynderblock rocket stove outside your rig when you arrive at location. It should set up in an hour or two. Insulate everything but let out the heat underneath the trailer (not the gas but the radiant heat from the pipe (use schedule 40 black pipe)). Put a skirt around the trailer. It should radiate a home that small very well. It's basically what you would call a ventless crawlspace and you're heating it. It's common and was done all the time by older civilizations.




Doug

Thanks Doug for for your ideas. I do understand that a RMH would add extra weight to my trailer, but I plan to keep this house planted and am only using a trailer to get around code. I'm hoping to use a mass heater if possible because I like the idea of cleaner burn, less wood, and not having to tend to constantly tend to the stove.

It's good to know the various options, however, as I try to sort through decisions for heating my tiny home. Not sure I'd want to have my main source of heat located outside of the house, but an outside RMH with exhaust channeled under the house is definitely a neat idea. Sounds fairly easy to set up. I know that it can get cold in tiny homes because the floor is raised off the ground. Perhaps to consider as a backup source of heat to whatever system I wind up choosing.

Thanks to all the permies members who have commented on my question. It does give me hope that there may be some workable adaptations to RMH's for smaller spaces.

Maureen

I too, fell in love with the RMH! I am building a tiny house on wheels in MN and I am looking for any way I can make it work. I love the idea so much more than a woodstove.

I really like the heated ventless crawlspace. Having lived in a one-room travel trailer for ten years in the past, the floor gets mighty cold no matter how warm you make the space. I would want to make sure there are no propane lines near where the heat duct runs, but aside from that I think it could work very well, especially if planned for in a new construction with no floor insulation and plenty of wall/roof insulation. You could assemble a dry-stacked block-enclosed mass under the trailer frame to give it some flywheel effect. It might not be as efficient as direct radiation from the duct, but it could make 24/7 heating much easier.

Stove options I have seen work in tiny houses and RV's are the Kimberly, the little Jotul, and the sardine stoves (for sail boats). Lots have talked about rmh but I haven't seen anyone do more than a pocket rocket. A 4" dragon should work, if you pay attention to clearances to combustibles. I love the idea of running the exhaust under the trailer to heat the crawlspace, but you need to be 110% sure you have no exhaust leaks.

My CottageRocket design fits the J tube and mass in a 24" diameter footprint. I designed it to heat my daughter's two story treehouse but it worked well enough to heat my 1100 square foot doublewide trailer in Cleveland for three years before I upgraded.

Hi, Chris

Do you have pictures?  I would love to see that Cottage Rocket.

Hi Anne;
Here is a thread all about Chris's cottage rocket    ://permies.com/t/150536/Uncle-Mud-CottageRocket-Paper
Plenty of photos's of them at the lab.