315 – More on Rocket Mass Heaters with Ernie and Erica Wisner Part 1

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Paul Wheaton sits down with Ernie and Erica Wisner to do a turbo podcast about rocket mass heaters. Ernie starts by asking Jocelyn what she feels about having the RMH sitting in the middle of the living room for so long, unable to be used. Jocelyn gives a few downsides to having that but goes on to explain how now that it’s running she sees a lot of advantages to it given that it burns cleanly, will reduce moisture in the house and bring the mould issue (that’s been happening due to the moisture) under control. Paul weighs in on it too saying that they’ve been running a propane heater which has been pretty unpleasant compared to the rocket mass heater, which he feels people are really excited about having there.

Ernie follows up with a question for Paul and Jocelyn, asking if the moisture issue has cleared up from using the rocket mass heater which Jocelyn explains that is has.

Ernie and Paul get into how they pulled out all the stops on this rocket mass heater with the aim of making it the prettiest most functional pebble style rocket mass heater possible.

Erica explains some of the designs done on the rocket mass heater and their functions. They discovered in making this stove that it burned at incredibly high temperatures. They discovered this by putting in 4 cones (temperature measuring equipment normally used to measure temperature in ceramic kilns) which were put on the floor of the burn tunnel at the very back (one of the coolest spots of the heater) and two of the cones (meant to withstand 1300 and 1700 degrees fahrenheit) melted down in 2.5 hours!

Since it was burning way to hot, they then had to figure out some methods to cool it down. Ernie explains that they cut the firebox in half, making it so that you could put much less wood being able to be put in, and they lengthened the ducts by 19 feet work to restrict the amount of heat coming through. Even after doing all of that – it melted those cones.

Erica shares a pretty groundbreaking concept that Ernie has been thinking about due to his concerns of all the plastic in the pacific gyre (an enormous island of garbage) – wondering if he can make a portable incinerator that could be put on a boat that could burn plastic cleanly and possibly power the boat. The particular stove at Wheaton labs is hitting temperatures which could make that actually possible.

Ernie shares that the stove at Wheaton labs is different from standard rocket mass heaters because of the high temperatures, which are being reached with even less wood. Ernie is developing a 4” system to be able to heat a large home. Erica goes through the numbers of how amazing it would be to cut your wood use in half, and then in half again, where you’d have wood in your shed to burn for many years.

They move back to talking about the cones, and Paul asked what temperatures Ernie speculates they’ve hit. Ernie feels it’s anywhere from 3000-4000 degrees fahrenheit.

They continue the conversation, between mouthfuls of huckleberry scones, revisiting some of the older rocket mass heater designs and results, and comparing them to the one at Wheaton Labs. Ernie says they are reaching temperatures they have not seen before.

Paul goes back to describe the original design of the poster child RMH, mentioning that he wanted the rocket mass heater to be pretty and go out of the wall. He gives a scenario of when people try to help, with good intentions, but not knowing about the system fully, which ultimately leads to mistakes with the RMH. Paul proposes a design that will be fool proof even if a well intentioned but lacking knowledge type of person tries to build a fire. Paul’s hypothesis is that the poster child rocket mass heater design (two pump system) in the main house infuses more oxygen into the rocket mass heater which is resulting in the extreme temperatures. Erica agrees and expands on the theory.

They give a few examples of how having the stove pipe next to the barrel gives the impression to people who don’t know how it all works that it is a very hot stove, reducing the chance of accidents and injuries.

They discuss the options for various sizes for different parts of the stoves and how it produces different results.

Paul expresses there is a lot of testing to go – and they discuss the possiblities and business opportunities of shippable core. They go over the benefits of having shippable core since it can reach people who don’t have as much time or skill or interest in building and installing rocket stoves themselves.

Ernie and Erica discuss some of their visions for the future of their work. Paul gives some details about the upcoming rocket mass heater DVDs.

They wrap it up by discussing the next year and what will come of the developments of the rocket mass heater, particularly the poster child RMH at Wheaton Labs. Paul gives a breakdown of the numbers of the costs comparison between natural gas/wood stoves etc vs rocket mass heaters, with the results being that rocket mass heaters are much cheaper. Paul also gives a greenhouse gas emissions breakdown since wood heat gives an incredibly low compared to natural gas and electricity etc. Paul makes the point that rocket mass heaters are probably even lower with emissions. This podcast will continue in Part 2.

Relavent Threads

Pebble Style Rocket Mass Heater in Paul’s Office
Rocket Mass Heater in the Wofati 0.7
Portable Rocket Mass Heater

Credit: Vida Norris

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