Jon Carter

After rebuilding the burn chamber twice, the feed tube twice, the heat riser twice with no success I finally tore into the cob covering the exhaust flu and shortened the flu by ten feet. Same results and a whole bunch of frustration. Because I couldn't think of what else to do and since I had the flu pipe all exposed I tried a burn with just the first five feet of flu pipe attached. Immediate success but since the smoke was now come out inside the shop I jury rigged a pipe to my through wall exit and immediately the smoke started coming back up through the feed tube. I had used a dryer cap to finish the end of the flu. I had removed the trap door portion and had covered the opening with 1/2 inch screen. As soon as I turn the open up so the smoke could exit up the stove took off and has burned perfectly since. Apparently the angled shed portion acted as a constriction - guess I should have seen it but I sure didn't.

I will start putting it all back together tomorrow and will test as I add back in flu pipe but should be able to get there now. Sure was great to see the fire rocketing away just like in the videos I seen of all your stoves.

Hope this helps some one to avoid what I went through - Jon

Good morning and thank you for the replies - Sorry Colin but I have already begun major changes. Your comments are still helpful though. I will make sure I don't have any tight or constricting spots in the transition chamber to the flu. My plan though is to completely rebuild the "J" tube portion of the stove. I have been modifying it enough that I have decided to stop with the "bandaid" approach and to just rebuild it using exact measurements from "the book". Figure this way I will have a better chance of it working properly. Besides it give the cob used as mass to dry out. Sure don't want to have to pull that all apart to shorten the flu pipe.

I do have a question though - I have been using fire clay/mortor to do the work including setting the bricks. I get lots of cracking and in some cases the bricks seem to be loose. Is there something I can add to make this better or some procedure I have missed. As I understand it I'm not suppose to add straw at this step. Let me know - thanks

Thanks Peter - it is looking like I may be having either a "man I missed that" moment or just a senior moment I'm not sure which. I left the barrel at full height (33") and brought the heat riser up to just under 2 inches from the top (31"). If I understand what is being said is that my barrel and heat riser are just too tall. Frankly that would be a lot simpler solution than other things I've worried about having to fix so other than feeling really stupid this might have a happy ending. Am I understanding correctly that my barrel should be no higher than 28" from the top of the burn chamber. If that isn't what is being said please correct me so I don't run off half cocked. If that is the case I am sure it was in the book and I just completely missed it.

Now that I think about it, if that isn't what is being said then please explain so I can get it - feeling a little thick at the moment - Jon

Thanks for the reply. I did take the complete bottom of the barrel out and the edge of the barrel is resting on a brick circle I used for directing the gases into the horizontal flu. I did check the flu for obstructions and it is free and clear and when I build a fire it does burn sideways to a large degree but any wood that is above the edge of the burn chamber will eventually have flames climb up them and there is not enough draw to suck them down and into the burn chamber. If I put a brick lid on the feed chamber so I restrict the size of the hole at the top I get less of this problem but it isn't cured completely.

I am trying to figure out how to post pictures so I can better show you what I have been up to.

One other thing - if I just try to start the fire by placing paper at the opening of the burn chamber I get no draw but if I first start paper burning in the clean out at the end of the flu just before it goes up the wall and out I immediately get draw and things start to look like the videos I've seen of a burning RMH. Once the fire gets rolling though I start having the issues I had previously described.

I have been battling mightily with my first effort at building a RMH. A few weeks ago I wrote in and received some comments but I am many steps down the road now and still not having any success so I thought I would try again.

I have been building this heater in a shop for a friend (I mention that for a reason that will be referred to later). It is on a cement slab and backs up to a raised 18 inch area also concrete. Seemed like a good place since it would allow for more "mass" effect. The floor was uneven so I built a brick base using fire brick and mortor. I then built the heater roughly around Ianto's book (I say roughly because I had been studying the book before building and then at the critical time couldn't find it) and made a brick heat riser. The stove seemed to rocket fine so I continued with the build. Now the problems begin - I installed the 6 inch pipe (flu) which would be enclosed by the cob and also the barrel. At that point the stove no longer seemed to rocket. It was at this point that I wrote this forum. Since then I have shortened the flu pipe with no noticeable improvement. I then removed the barrel and removed the brick heat riser - installed a metal heat riser made from a piece of 6 inch pipe inside an 8 inch pipe with perlite/clay insulation in between. Once again it seemed to rocket very well so I reinstalled the barrel and lost the rocket (it still draws but nothing you would consider a rocket). At this point I decided that it must be the fact that we had no cob around the flu so we began cobbing the flu. My intention had been that we would only go half way down the bench so that we could still shorten the flu if necessary (there is 30 foot of pipe) but I was gone for a weekend and my friend finished the cobbing so now all the pipe is covered. Still no rocket. In the initial build I had added a clean out pit and door to the feed tube area and decided I might be getting enough air infiltrating to cause the feed chamber to lose downward draft so I rebuilt the feed tube and eliminated the clean out door.

Long lead in I know but here is my first question (sort of a hope without much faith) is there any chance that the draw will improve once the cob around the flu pipe dries out? I am able to build a fire that burns adequately as long as I put in small pieces of wood and keep the fuel low in the feed chamber. I also have narrowed the feed chamber and put a brick on top to narrow the area air comes through. This keeps the fire from coming out of the top of the feed chamber but if the wood is put in just a little wrong the fire chokes and starts smoking back into the room. We have directed air across the feed tube opening from a fan and the fire seems to burn pretty well - I guess we are adding the rocket by force feeding air.

A couple other comments and then I will stop. At one point I decided that I must have made the burn chamber (bottom of the "J") to large for the 6 inch system so I installed 1 inch thick bricks to narrow the chamber. I am now sure that the chamber is smaller than the 6 inch pipe.

Is it possible that I don't have enough insulation in the heat riser and should go to a larger outer pipe?

Any other advise will be greatly appreciated - I am at my frustration limit on this one. Thanks Jon

Thanks Chris - that has been my concern since the weak burn. I had read that point in Ianto Evan book but hoped I was close enough. Thinking now I will restrict the burn chamber by an inch as one more of my learning processes. Lots to learn in these little buggers.

Thanks for the input - I am shortening the flu 10 feet and will try it that way. Then I am going to make an metal heat riser (6 inch inner tube and 8 inch outer) and give it a try. Last thing will be to extend the mass and see what that changes. Hopefully I will learn a bit from the different approaches.

Also I have been burning both types of wood and you are right the apple wood burns more like I was expecting.

Hello - have been building my first RMH and am getting a weak rocket. The stove appears to burn properly as long as the wood added is short but anything more than half the way up the feed tube will eventually have flames work there way up far enough to get smoke and limited flame into the room. So I have questions:

The heat riser is brick and clay mortor - and reaches to just under 2 inches of the top of the barrel. Could the fact that the clay is still some what damp hurt the draw?

The flu is about 35 feet - could this be too long (six inch flu pipe) or could the fact that I don't have mass around the flu pipe yet have an affect?

The burn chamber is 7 inches wide by 5 inches high and the heat riser is 6 inches by 6 inches - could there be an issue there? I narrowed the feed tube with little difference.

If I just drop short piece of wood in the feed tube the stove burns well - a tiny bit of smoke and or steam and some condensation is all that come out the end of the flu.

Sure would be interested in your comments - this is in my shop by the way - Thanks in advance - Jon