RMH - smoke back - bad draft with barrel on

Hallo dear rocket enthousiasts.

I've been reading and studying a lot on the rocket stove concept as I find it a very interesting one. After long thought I started building the heater part, just for experimentation and building a terrace heater to use on those summer evenings when you want something to heat up the surroundings.

I built the core in ytong, and without the barrel on, it works great (see my youtube channel for the burn test without the barrel)

But if I put the barrel on, things seem to change to the worse. At the beginning, the system draws, but quickly it seems as if the system is gasping for air, no rocket effect and constant smoke.

https://www.youtube.com/watch?v=JAXCfir25do

This is where you can find a video showing the smoke back...

feed tube and burn tunnel are 100mmx100mm

Heat riser: 200x100mm inside.

The heat riser has been insulated and I built a wooden box to fill with dirt to create an as gas tight possible assembly as cheap as possible.

I've been reading on the forum that a decent chimney shouldn't be necessary but I'm seriously doubting it... Would it help to stick on some more chimney duct on the elbow?

The elbow has a diameter of 125mm by the way...

Any suggestions on how to improve the system and making it roar like a dragon, when the barrel is on would greatly be appreciated. I'm having loads of fun experimenting with the system and building it all with my own hands. I'm not at all that very handy, but I manage

Ivo Staelons : Your U-tube Video is marked private, so no joy there !

Ianto Evans who observed the operation of heat risers directly above and part of the Combustion Zone, and converted the Rocket (cook) stove into the 1ST
Rocket Mass Heater RMHwanted to prove that a final vertical chimney was not necessary.

He moved to/founded Cob Cottage, an area with a very stable micro climate with steady winds during HIS local heating season. Then he went ahead and built
his houses For his Rocket Mass HeatersRMH, almost all one story squat Button Mushroom shaped buildswith the final horizontal exhaust Always on the Lee side
of the structure.

It is a point of pride to him that his systems work, and that some if these RMHs cost very little being stored/hoarded/found materials !

Almost universally we are attempting to adapt the RMH into our homes, and Universally were are finding that a Good Final Vertical chimney is Necessary !

So- Remember This Golden rule for testing your Rocket* !


As soon as the Barrel goes over the Heat Riser a Vertical Chimney must go up !!!


This serves a great second function by uncoupling Your Rocket Burner, and Burner base from the Thermal Mass. If your Rocket is not Rockety with
enough Vertical chimney to clear all near by objects by 1.5 meters and installed immediately after the Burner base- then your problem is in the rocket
itself and will need a rebuild !

Another pretty Universal rule is that the internal plumbing should all be of a common size throughout !

For the Good of The Crafts ! Big AL


*(Best done as a primary build out of doors )

allen lumley wrote:Ivo Staelons : Your U-tube Video is marked private, so no joy there !

Changed the settings, I'm new to working with youtube and learning as I go. You should be able to seeing the terrible result now

allen lumley wrote:

Almost universally we are attempting to adapt the RMH into our homes, and Universally were are finding that a Good Final Vertical chimney is Necessary !

So- Remember This Golden rule for testing your Rocket* !


As soon as the Barrel goes over the Heat Riser a Vertical Chimney must go up !!!

OK. I'll go and buy a piece of stove pipe tomorrow and see what I can do.

allen lumley wrote:

Another pretty Universal rule is that the internal plumbing should all be of a common size throughout !
For the Good of The Crafts ! Big AL

OK. I'll redesign my core and retest.

Thanks very much for taking the time to read the post and give your remarks. Realy appreciate your time.

I'm testing the thing outside by the way.

I'll keep you and the rest of the readers posted on my progress.

Allen, you are right of course.
However, during the Innovators gathering due to time constraints we tried to burn the paint off a barrel simply by placing it over the riser. The difference being here, the rocket happened to be the 8" mock-up batch box and the top gap was about a foot. Maybe it was due to the greatly larger power and/or the huge top gap but to our surprise it worked!

Ivo, I'd recommend to just try the same thing as you tried before, with the barrel one foot higher this time. Simple to do, nothing lost. When that doesn't do the trick, you need definetely a vertical stack in order to get your rocket going.

Peter van den Berg : You are right about the Batch style RMHs, more and moreI find my comments here at Permies to be dated, But I am having a little bit
of difficulty wrapping my head around the whole idea, Throw in bells and I feel like a dinosaur waking up in central park !

I had a great grand mother who had only been on a train once in her life, and never road in an automobile, and was afraid of them till the day she died.

I kinda know how she felt ! Big AL

Follow what Peter and Allen have said! And also, redo your plenum. The conexion between barrel and chimney has to be big. Not just a pipe sticking in the barrel gap. This has to do with the change of direction inn gas flow and the boundary layer. The bigger the better. We usualy say, 3 times the CSA in rign projection (of the chimney pipe) for it to work right.

Hi all,


I installed a 2m chimney pipe and that seemed to have solved the problem.

"If the barrel goes on, the vertical chimney must go up" certainly is a rule of thumb.

At the rest of my setup I changed nothing. The stove actualy roared at some time and burnt hotter then it has ever done.

Perhaps it can be tweaked here and there, but I certainly have a working prototype now

Me happy!

Thanks all for following and giving advice.

Regards

Ivo S.

Hi all,


After a lot of test burns on my prototype I took the time yesterday to take the unit apart and visualy check every component and overall looks.

I took some pictures and made a small you tube dia show from the results.

I'm very much looking forward to hearing the experts' remarks!

https://www.youtube.com/watch?v=GmMKnRzuhD8

I've embedded the video below.