Podcast 271 – Rocket Mass Heater Shippable Core Update

Paul and Erica discuss shippable cores along with work done at the tipi. One of the days during the workshop included flooding the tipi with heat because the mass was frozen, frozen rock solid. The next day, after heating up the mass the heater worked much better. There were many projects going on all at the same time. Forming molds seemed to be very interesting to Erica. Part creation from molds by Tim using welding was very helpful. The molds are in good shape. Highest priority was the tipi. A review of the pocket rocket sitting on top of the mass and some of the clay was glazed over. The mass did thaw out but getting more cob on the bench still needed to be done. The finish layers of cob still needs to be done. Two people are now living in the tipi. Getting the mass dry was most important. Shortening the path was Erica's first priority. They stripped the flow back to the first cleanout. Erica showed the best way to start a cold pump. Insulated heat risers seem to be a little trickier. Erica spent lots of time checking out the smoke. There was a little aroma left but the core was working. Erica moved to the next section of pipe. Paul discussed the smoke and the smell coming from the smoke. The short run of pipe from the manifold could also contribute to the odor. Erica noticed soot on the pipe too. The riser seemed pretty clean. The bench is C shaped and the top of the C is where the combustion chamber is. There is a small wiggle to triple back under the bed. The back had not gotten warmed yet. Using a simple C pipe they rerouted the exhaust. There was condensation dripping from the exhaust using a vertical pipe. They used black stove pipe to go up thru the top of the chimney. Paul pointed out that the black stove pipe was supposed to be used for the first runs coming out of the rocket mass heater. Paul said that he never wants to see the green smoke ever again. Swapping the black stove pipe ends the dripping of condensation stopped. The RMH continued to work ok. Erica thinks the core seems to be in pretty good shape. They are using a propane heater and a pocket rocket to continue to thaw the mass. Rather than feed in wrist size wood Paul thinks feeding smaller wood in would make it run hotter. Caution has to be used to keep the coals to a minimum and not choke the fire out. A wood shed to keep the wood dry is very important. Burning wet wood is no fun. The next day the excavator was used to break up the frozen cob. Bricks were remortared in place. The loose bricks allow air in. Using clay alone is not good. Clay mixed with sand will usually not crack. The cob is still not fully dried out. Because of the time of construction fighting the weather is problematic. Had it been built in the summer, drying is easier. Spring is the best time to work with cob so it dries over the summer. Tony is keeping the stove going every night now.

RMH in the shop with Tim was next.43" tall hear rise. It was to short combined with other problems this design would not work. Using some rings and cut barrels parts they stuck it together and it drafted so warm that the glue melted which was rated for 300 degrees. The tape stunk up the auditorium. Paul wants to get rid of all that tape. It smells bad when it gets too warm. Now the riser is 58" tall, Bare minimum is 48" with a 16" wood feed. Because the bench was not heating up Erica thought it might have been a lack of insulation. The draw on this rocket mass heater was very strong, so strong that it made it hard to light kindling in the feed tube.

Shippable core progress. Erica helped Tim casting in the concrete with a few pointers. An after dinner casting sessions was reviewed. They mixed up four batches and poured the core. There is an event planned for innovators for 2014. With more people helping out, lots of experiments can be performed. This type of relationship is good for attendees and for people innovating by trying out different ideas. There is now an accumulation of tools and supplies for making rocket mass heaters. There was a little more work done on auditorium heater after the batch pour. Meals are packed with people discussing permaculture and rocket mass heaters. Many people who attend have very interesting back stories and they can contribute a great deal. The diversity of knowledge makes the heaters that much better. People are very giving when it comes to sharing.

Innovators event, coming up. 25 students two sets of workshops. During innovator weeks there will be 6 innovators and 12 assistants. People who are trying new things are those considered "innovators" not those who can build a good rocket mass heater. Building is important but trying new things in a build designear back, post to the "Tinkering" forum and invoke the 48 hours rule. Dragon heater folks are very active on the forum now too.

Credit: Kevin Murphy

You can discuss this podcast on this thread at Permies.

Relevant Links

RMH in a Tipi Thread at Permies
rocket workshops / innovators gathering / September 2014
Shippable Core Thread at Permies