Ok, So I have only posted here maybe once before but I have been gleening info from these forums for months. Also I have the DVD set that really helped in my research.
I have a 6" system and we fired it up last week for the first time in the greenhouse. It's been really cold here the last week with temps in the low teens and tonight maybe into the single digits. The greenhouse houses an aquaponics system and so far none of my pipes that carry water for the system have burst which I attribute to the RMH. I fire it up every night and feed it for an hour. Within a minute the barrel is too hot to touch on top. I have good draw up the feed tube so all seems to be working.
MY QUESTION: The exhaust pipe is about 10 feet long and then it runs up and out of the greenhouse. Mostly its steam. The pipe never gets really hot...only warm. I have the pipe surrounded by larger rocks and towards the barrel its also covered right now with some clay dirt as well. I have some sand underneath the exhaust pipe to insulate it from the ground as I read on this forum a while back that this will help prevent losing heat into the ground.
Could something be wrong if my barrel is really hot but my exhaust pipe only gets warm. I was hoping that the exhaust pipe would get hotter than it does to help heat the greenhouse. I mean, how is it supposed to heat a bunch of cob/mass that gives off heat for 24 hours if its only getting warm? The steam coming out of the end of the exhaust pipe is slightly warm.
I also realize that the greenhouse is not insulated like a house with a RMH so the heat generated will dissipate faster. I'm open to ideas. I just want to get the most heat that I can this winter.
55 Gallon Drum
1.5 inch clearance from riser to drum top
Using sand and perilite for insulation between riser and outside of burn chamber.
Many thanks to everyone who put this forum together! It's really helped in this project.
Zach B. : Metal is Doomed ! You will not get an entire heating season out of your build before it starts failing apart ! Please Due anGoogle search for
"High Temperature Hydrogen Attack" , 'Hydrogen and Steam Embrittlement' You literally have only a matter of a few days to re-build your whole system
In the best of allI events you would be cycling about 60% of your heat through your Thermal mass, it will not help you save your outlying simply lines.
You may get a few more days out of your system by moving your waterlines in from the perimeter but that is chancy at best !
If you are truly eager to save your fish you will need to immediately goto Rocketstoves.com to Download the Brand New 3rd Edition of 'The Book'
Rocket Mass Heaters . Do not 'Buy the Hard copy' you need to have the downloadable copy in your hand NOW, and Commit to a total rebuild !
I expect that you have been victimized by the endless stream of near worthless you-tube videos ! At this point I can not tell you what is salvageable from
The Thermal Mass portion of your build, but from the Rocket Burner base I expect that you will salvage only the barrel and the two fire bricks !
For the Good of the Craft ! Big AL
Late note you may want to P.M. Me !
Success has a Thousand Fathers , Failure is an Orphan
LOOK AT THE " SIMILAR THREADS " BELOW !
posted 5 years ago
While I'm not opposed to an entire rebuild of the heater, I figured for sure that quarter inch iron for both the inner riser and the outside would be sufficient to last quite a while. Are you saying I should only use brick?
Zachary, you can build the rocket core with bricks or with a castable refractory. The castable refractory gives you greater freedom to optimize the shape of the fire path. Here is a video that depicts the process of making a diy refractory mix. While it is on youtube, it is information from a well respected stove craftsman.
All I can add at this point is to repeat much of what Al has just shared...
We are running into a lot of questions about RMH and other topics from folks that, I am sorry to say, watch way too much Youtube.
Yes there is good info out there, both on Youtube and in the general body of the internet....however....only about 20% (more like 5% from what I have been told by those that actually study the overwhelming mass of it) is of any use or coming from reputable sources with more than 15 years of experience in a given subject (15 years being a baseline for knowing the "ins and outs" of a subject to then teach others about it...)
Again the video that Amos has shared is another "DIY Refractory" of unknown thermal characteristics or durability. Some of these formula modalities have inherent good thermal insulative characteristics...but...that does not make them actual "castable refractories," and I don't want us to get into the habit of repeating bad information and/or partial information unless we know for certain that the information shared is worth passing on, either from our own experience or years of working in that particular discipline/field of study.
To be an actual "castable refractory" The material will not contain any regular OPC (ordinary portland cement). For high-temperature applications you find in kilns, crucibles (probably the most enduring of this lot,) ovens, stoves and the related combustion chambers, will require the use of a refractory matrix. OPC base matrix will be damaged or destroyed by elevated temperatures, and any formula using them are doomed to eventually fail if not sooner...not too later. Base fundamental materials that always are in, as far as I have ever learned or experienced, castable refractories will have their base components made of major portions of calcium aluminate, fire clays, ganister and minerals high in aluminum content.
Most folks are trying to "cut corners" on cost of many refractories...they can be very expensive. Unfortunately, that is just the nature of the materials in them and the cost of time in using materials that are not meant to be used this way...is not only costly in and of itself...it can be dangerous. I would also note here that even among refractories, many are consider a "sacrificial element" and are often designed (or should be if the design is a good one) to be replaced and/or service when needed.
??pozzolan portland cement?? Did I write that term someplace? Send me there so I can edit that...
Pozzolanic materials in general are not considered "refractory materials." There are some within this family with high content aluminates that have been used as a mortar additive (as I understand it historically) in ancient bread ovens. This is a much different context than a true "castable refractory" and clay mortars have been used historically just as successfully...at least in bread ovens, and pottery kilns.
Some additional links worth reading for RMH builders considering castable refractories:
There is no doubt that there is a range of temperature tolerance achievable with different cementitious matrix. What I have been trying to make a point about is not confusing a "true refractory" from a thermally resistant and/or insulative cementitious matrix. A material of this nature, used in an "element" of a flue (do we know the durability and projected life expectancy...remembering that many of these are considered "sacrificial" in nature) is not anywhere near the same as forming an actual castable refractory material...