Abe Connally wrote:How do you guys do your ash drawers, and where in your RMH designs do you put them? I am currently building a RMH, and I plan to have an ash drawer below the feed tube, and then another cleanout at the exhaust exit. I'm not sure how to do the exhaust one, cause you pretty much want things air/smoke tight at that point. Any thoughts?
R Scott wrote:I don't know if I have seen an ash drawer in an RMH, and I have looked at a lot. Most say they don't produce enough ash to worry about.
Abe Connally wrote:for the one below the feed tube, it will be 16 gauge metal, welded up to form a box. I may put a grill above it to prevent whole sticks from falling down in there.
I am new to this, so please take my concerns with a big grain of salt, but it seems to be that grilled compartment below the combustion chamber would be a de-facto increase in the open space surrounding the burn chamber affect air flow and burning.
I’ve been cleaning out the burn chamber on Sundays. It’s best if I let it settle down on Saturday, so I’m not pulling out hot coals. There is around a gallon of ash every week.
Reaching down into the burn chamber to remove the ash can be lame. There is room for design improvements here. I’m sure someone has already figured this out?
Abe Connally wrote:here's a photo of what I'm talking about with the ash drawer:
Abe Connally wrote:and here's from Ianto's book, Rocket Mass Heaters, page 23:
I think if you set the ash drawer down below, like in those diagrams, it won't be exposed to the majority of the heat, because it is sorta shielded by the bricks. I think 16 gauge metal would work, that's thicker than what the metal barrels are made from. Most regular wood burning stoves are made from 16 or even 18 gauge, and they handle the heat just fine.
If you put a door or easily removable bricks where those bottom two brick are on the left of that picture, it should work. I don't know how long it will last that close to the heat, but at least you could build a cleanout that fits an ash rake.
There's always going to be ash. You may not see it, but there is ash. If you look through a few reports from Google, you'll see people are pulling out a gallon of ash a week.
tom Brue wrote:Forgive my ignorance, but my understanding is that the ash content is little to none (ideally).
tom Brue wrote:Most designs have the cleanout on the chimney end. I suppose the idea is that the velocity of the gas going through the burn chamber is so high that ash is sucked through. Once in the chimney, as the gas cools the velocity drops and ash would fall out, depositing along the bottom.
tom Brue wrote:Here is my planned design. I intend to build the whole system out of circular stove pipe of different dimensions and then insulate with vermiculite/mud. So let's say your feed tube is 6" stove pipe. Can you just drop vertical about 18" into a T fitting? The fire and heat would go one direction through the T. The other side of the T would just be a removable cap. When the fire is burned out, just pull the cap and rake out any ash that may be there. Does that make sense with the T pipe? So the beam of the T would be the bottom when put in the stove, and the post of the T would be the feed chute.
I know there are hundreds of proved designs out there, but I can't help by tinker myself to see what I can do. Referring to my first post, I intend to build a micro RMH. I'm going to model it all with movable insulation (sand) and then once I get the kinks worked out, I'll assemble the permanent setup. If in the model I don't see any ash problems, then I probably won't build in a cleanout in the burn box.
allen lumley wrote:# Edit:
Boy is my face red ! I took the sketch you showed us as a "planed build sketch" you can see what caused my deep concerns ! Yes sir! You do Have a Rocket Stove Mass Heater! Yes Sir! You Do have a Rocket Stove Mass Heater! Yes Sir you do have a Rocket Stove Mass Heater ! I had the Idea of the 1st sketch in my head when 1st looked at your pictures, and pre-judged what I was going to see- tho you clearly had a Transition piece to carry exhaust gasses away at the bottom of your Chimney i never saw the third piece of stove work carrying the cooling exhaust gasses down to your chimney ( Except in the Final pictures ) Please accept my sincere apologies , I Think i get it now, again, bringing your build to this forum is a gift from you to us and I'm sure that everyone who will see this will take away some thing that they can use from this, can we please have a little more information on the Temps you are geting and where ! Sincerely Allen L.
Chris Sturgeon wrote:I'm obviously missing something here. From what I'm seeing in your pictures (nice shots btw) you have some sort of heat Bell in the combustion chamber before the heat riser. Is this right? Is this where the water/ water-jacket is?
Sorry: I've read into your explanation a bit more and I see that you've put thermal mass vertically around the exhaust chimney. Do you get enough dwell time of exhaust on thermal mass to transfer heat well? I'd love to know what the exhaust temps are at the system's outfall. If it's working well (ie: scrubbing enough heat from the off-gasses) then this would be a good fit for those looking at a RMH with a smaller footprint.