He's got a nice looking batch box RMH. They are great for delivering a huge blast of heat into the mass, whether it is cob or water, without regular tending. Peter van den Berg has researched the style extensively and found the ideal dimensions and proportions for best efficiency, and it doesn't look from that video like this build has all the best features, so it could still be improved. Any heater that doesn't try to send the flue gases through a long horizontal path will obviously have easier draft; I wonder how much heat is going up the chimney here. The wood comparison is misleading, as he shows a bunch of crooked sticks for the single J-tube load and straight logs for the batch box load. A J-tube delivers heat to the system over a longer time, and it depends on your personal lifestyle whether that is good or bad. A batch box burns best when starting with a full load, and you can't safely stop the burn in the middle. A J-tube can be burned for exactly as long as your experience tells you is needed.
It would be interesting to know how long the duct run was for the original J-tube and how many elbows, what size, etc. Maybe the earlier videos in that series give that info.
I looked at a lot of stuff from this guy, ummm I wood look at all his videos. I no longer follow what he does for a few reasons. The major one being safety of which I did not see. To put a copper coil on top of something that hot? He also pots thing as successful only to comeback and update less than positive results. He sounds really good then not so much.
A water mass in a tiny space is a goal of mine as well as heating water. So I looked long and hard at his videos but found flaws that are IMO are a danger to the craft.
Location: Upstate NY, zone 5
posted 4 years ago
Yes, that 3/8" copper coil embedded in the top of the barrel looks rather precarious, though it is small enough that any steam explosion would have relatively limited area of effect. Another concern with it is that even if it sends boiling water to the tank, it can only absorb so much of the heat generated and will only be transferring heat while the fire is burning. A big open tank on top of the barrel with the coil sunk in it would extract heat more efficiently as well as more safely.
Allen Sharp : Several of us Rocketeers ardor have followed his designs . you could write a book comparing his 3 builds the one before he attempted to build
a Rocket Mass Heater RMH, and the short period of his RMH use and now this !
By starting with a larger size copper tubing wrapped from low on the barrel to higher on the barrel he could improve his Thermo-syphon.
Obviously he was not satisfied with his 6'' j-bend system, but we have few details other than His inability to quickly bring it up to operating temperature- This
is a Benchmark by which we measure whether the Rocket is a functioning unit, apparently he was unable to find the problem and solve his issues
I am aware that his Much larger system allows him to load up a horizontally fed system similar to a batch box style, he then draws a comparison back to his
attempt to build a 6'' vertically fed J-Bend System. Its his comparisons between the two systems I am having problems with !
I am not happy with the idea of leaving ether model unattended ! In a perfect world you can have your RMH Centrally located and tend to your fire while you
are home, interspersed with the other duties of home ownership, you pick the time that is convenient to you, The Vertically loaded fuel needs little adjustment
while his attempt at a batch box style rocket will need fiddling with to provide a clean burn, he has no additional thermal mass after the barrel so 1) his system
has to draft better than most Rockets but-2) With no way to collect that heat more is going up the chimney, it is very much like building a fire in a wood stove,
leaving the wood stove door wide open, and wandering into another part of the house! this drops his efficiencies much lower than he is willing to credit !
Again, starting with a warm RMH, you should be able to bring it 'up to working temps in 10 minutes, with minimal tending while you are home, 3-4 hours of
Firing your Rocket should give anyone 24 hours of heat, No one should ever be up starting fires at 3a.m. because the house is warm 1st thing in the morning
that whole task is put off till evening, and if the house has cooled down a little when you get home after work, then is the right time to start rewarming
During the empty home time there should be zero heat energy loss showing at the chimney of the J-Bend style RMH -against a constant heat energy loss
signature at the chimney with his attempt at a top loaded Batch box system !
So really it comes down to knowing your system, comparing apples to apples, and his need to improve his system, A True batch box Rocket will easily out
perform his model ! A J-bend style heater while needing more attention is more frugal !
The entire Family of Rocketeers are all Pyromaniacs- it is possible that he is just one of those unfortunates incapable of grasping a manner of living that makes
tending to a rocket mass heater much like having a comfortably ample bank account into which you make regular deposits of small, very dry, Thin split wood,
and automatically get regular disbursements in the form of Heat, Bone warming Soul soothing and warming heat !
Some times these people make happy marriages with other people who quickly come to understand that they must embrace that part of the 'wild side' of
their personality to help make a warm and happy home !
We can always pray for them ! For the Good of the crafts ! Big AL
Success has a Thousand Fathers , Failure is an Orphan
LOOK AT THE " SIMILAR THREADS " BELOW !
And tomorrow is the circus! We can go to the circus! I love the circus! We can take this tiny ad: