I've been looking for more info on the the Rocket Stove Mass heater and I keep finding new stuff. (Old published stuff, new to me sort of stuff.)
One of my recent finds (That reminded me of this forum) has been an advertisement in Popular Mechanics from, Feb. 1981. This diagram looks a lot like a Rocket Stove that may have been produced by Madawaska Wood Furnace Company. Their model doubles as a water heater and features a blower on the unit. Madawaska Wood Furnace Company Linky This is a link to a page on Google Books.
Here's some Wikinfo on on the Jetstream Furnace that gives some spec details; Wikipedia Linky
This Jetstream Furnace looks like it would fall under the category of appliance. (IMO.)
Here is Richard Hill's Study (PDF download) showing his experiments and detailed info... (Man, I loves me some Google.) Dr.Dick Hill Linky
There's some good info here (That may already be posted on this site...) and I just thought I would share what I found. I've been contemplating scrapping together stuff to build my mass heater in my building/art studio.
There are some nifty things going on with rammed earth in Australia that they are using for wood burning stoves, I don't know why it hasn't been done with rocket stoves yet, but I think this might be where I go with mine.
posted 9 years ago
While similar the burn systems are indeed a bit different than the rocket stove.
There is a commercial boiler using very similar design to the RMH and it shares a lot of "partial" similarities with several designs.
I really had hope of having some preliminary testing done this week but huge hurdles involving other projects have interfered and may have in fact pushed the entire project back as much as 60 days.
The units using hydronic heating methods have some advantages over the RMH design in transportation of the heat generated, the RMH has advantages in heat storage.
On this web space there is a hut (sorry to the owner, this is not insulting your "hut", simply do not recall the correct term used for your relaxation space you built and it appears dome shaped like a hut) that uses the exhaust from a RMH to attempt radiant floor heating and have had success at getting heat into the space to a comfortable level. I have been critical of the design due to the over-extraction of heat from the exhaust gases, not the design itself, well sort of, but those criticisms have points and counter points supported on both sides and my comments were driven by the Uniform Mechanical Code and while 100% accurate for some locations, there are indeed opposing codes and regulations that make either position viable and acceptable depending upon jurisdiction.
The main point is, radiant floor heat is AWESOME! I really believe a RMH design can be adapted to use hydronics to effectively do it, keep the exhaust temps reasonable and "code compliant" and perhaps even possibly "lower than the norm" though I have little confidence we can get that done, there are just too many nasty components in the burn byproducts that create problems and safety issues.
The draft system on the links provided uses an electric engine, the RMH uses another method. Controlled draft is key, with electric engines we can operate under a variety of conditions and effectively have excellent combustion of wood fuel, in fact adding a cat to the system and a few other mods, extremely clean exhaust, far beyond what is in current production is possible. Under the restriction of cost effective design and limited maintenance you would find such designs within the capitalistic system to be "cost prohibitive" at best.
The RMH and supporters BOTH oppose that, the RMH is in itself an engine that drives the draft, requires no external energies to drive it, currently operates under only a narrow range limiting conditions, requires only moderate maintenance, is not cost prohibitive, may indeed be capable of extremely clean exhaust, and offers a group of supporters an alternative to effectively provide heat without impacting the environment in any negative manner that is not renewable or naturally disposable.
The goals surrounding the RMH are simply to improve the technologies after proving them out, expand the range of conditions aka vary the capacity and usability without taking it into the "high tech" side of the world, aka, keep it within the "person with a tape measure and motivation" can produce item.
I fully believe we can reach that goal despite the fact that it is pretty unlikely that I shall ever own one outside of my laboratory myself. Appreciating or even admiring that in which you do not participate in is not as uncommon and some might believe.
Professor of Thermal and Electrical Engineering, Welding/metallurgy: Licenses: PE license, Mechanical license Variety of other "certifications" from industry groups such as Refrigeration Service Engineers Society http://www.rses.org/, ASHRE http://www.ashrae.org/ Ect.
posted 9 years ago
The draft system on the links provided uses an electric engine, In the PDF the model does have a blower, but later in the study talks about extreme temperatures (Which, is what you would expect from dropping a blower on any fire operated device. ~e.g. Forge, Kiln Incinerator, etc.) Hill mentions that you can simplify his model without the use of a blower.
...The blower is very interesting if you were wanting to make a high fire kiln. You would still have to have some serious mass to retain the heat on cool down side. (Most ceramic kilns are like this anyway.)
Controlled draft is key, with electric engines we can operate under a variety of conditions and effectively have excellent combustion of wood fuel, in fact adding a cat to the system and a few other mods, extremely clean exhaust, far beyond what is in current production is possible. Under the restriction of cost effective design and limited maintenance you would find such designs within the capitalistic system to be "cost prohibitive" at best. Hill goes on to talk about the first ten to twenty minutes of the firing of his unit and how it has back fumes/smoke (backdraft) until the unit heats up. To avoid this, I think it makes sense to place some sort of fan in the upper portion of the exhaust tube that exits the building on initial start up. (or some sort of fan to force the air off the front end that would allow for the ignition of fresh cut/green wood.) It is the heating of the refractory that reduces the smoke emission.
I don't see the difference between Hill's model, or a RMH. The RMH seems to be a combination of a Masonry Mass Heater and Hill's model minus the water & gadgets. The idea of attaching a boiler or some sort of radiant water heating device it actually pretty dangerous considering the high uneven temperatures you get while heating. This hydro-heating is a great idea, but you would have to have constant access to service the conduit under a floor to replace eroded pvc, copper, cast iron pipe, ceramic joints... The old school way for hydro floor is harnessing the temperatures of the earth... 40+ feet down in the earth with pipes filled with water that cool/maintain a constant temp in a slab floor... This was used with earth berm homes of the 70's (I think.)
I can see where it is objectionable to add gadgetry to the RMH. I am in my collecting data mode, which is why I posted the links. Hill's "Stick Stove" study has good info including, why there isn't a need for an outside air draw and the the chimney being though the roof and not the side of the building. (Which, for some reason I am seeing with some of the experimental RMH videos.) I agree with the purist sentiment that the RMH's needs to be gadget free.
Thanks for your input Ned! This just made my wheels turn a bit more.
The Madawaska Stove was under development about the time I left Madawaska Maine. The preliminary drawings that I saw were for a small diameter tank welded at an angle into a larger diameter tank to provide a wood feed tube. The wood feed tube had to be tightly sealed to prevent the fire backing up into it. The idea of being able to load three or more rounds of firewood into a stove and have them burn intensely at only on the draft end appealed to me some thirty years ago and I had the materials but not the time to do it. The discussion of rocket mass heaters on permies has me thinking about it again. A feed tube for pellets was developed by this man https://www.youtube.com/watch?v=7wqJQmD-eVo His Idea of installing a gate to stop the feed while he was loading or to let the fire burn out seems like a good idea. With solid wood I don't think a grate would be necessary. With a rocket core in the large tank I think I could achieve efficient heating for the large chicken house that I plan to restore for green house/workshop. This originally was built with a mass heater in the north third. This was a firebox and horizontal flue encased in 16 inch run of cement that ran 2/3 the width of the building from the outside fire door and then up a brick chimney through the roof. This provided a large warm area for young chickens to snuggle up to in cold weather.
I have a heat exchanger that was used with a oil burner to heat a 100x100 foot store. It is large enough that I think I can put the rocket core and riser in a barrel inside it. This would give me air heat exchange drawing cold from the south end of the building under the floor then venting through the old mass flue give mass heat tor the north end of the building. The draft and feet tube would be under a shed roof on the outside of the east side of the building. New thought as I was proof reading; if the flap gate hinged at the top of the feed tube was linked to a flap gate on the draft then when the last of the wood passed through both would close stopping the siphoning of cold air through the stove and cooling the heat exchanger and mass.