6″ Dragon Burner Masonry Heater using chimney flues – Part 5

Here is the masonry heater with stacked stone applied.

Dragon Heater Castle Build - Rocket Heater without a barrel

Dragon Heater Castle Build completed with stacked stone. (Click to enlarge)

The feed tube box is rose wood. The caps are cast refractory that have been painted with high temperature – Rich Metalic Brown. The steel top plate and ash clean out door were painted the same color.

Frankly the pictures don’t do it justice. We were very pleased with how it came out, but we had a hard time photographing it. Hopefully we will get better shots in the next few weeks.

We left the backside open so we could show visitors how it is built, so here is a shot of the back. Kits will be available soon!

Dragon Heater Castle Build showing how the stone and chimney flues relate

Dragon Heater Castle Build showing flues


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  1. Wow very nice!! The flues are hard to get here in San Diego, so I need to get it somehow.

  2. Did you try brick suppliers, they usually carry them.

  3. This really looks fantastic. I would love to see some additional details on the finishing steps.
    Well done !!!

  4. Very impressive, Sandy! As a dragonheater customer, it is really nice to see the continuing innovation you and the team are showcasing.

  5. Wow. That stone work is beautiful.

  6. Max Kennedy says:

    Nicely done. Would it be possible to post a cutaway view of the 2 main sections, ie the feed/burn chamber/heat riser section and the bell#1/bell#2 section. I’m a bit confused about the air flow in bell#1 with the liner. Also from your last photo’s in part 5 is the green at the bottom right of the back a horizontal exhaust? Could this be exhausted vertically through a roof? I’ve been thinking of a design somewhat like this for 3 rooms in my house. We have a very long kitchen/dining room with the living room/master bedroom sharing a common wall with it. Rather than cut out entire walls could the feeds from the heat riser to bell#1 and bell#1 to bell#2 be short horizontal pipes through a wall? I’m thinking Burn chamber/heat riser in the living room, Bell#1 in the kitchen/dining room and Bell#2 in the master bedroom.

    • We have been working on some flow drawing and will post something soon. In the meantime, you are actually the 2nd of person, (I am sure many to follow), that want to split the 2 bells, with a bell on each side of a wall and have the exhaust passage going through the wall to the 2nd bell.

      Yes this would be possible, but since the passage will be warm, it will need to well insulated. I would think 5″ of rock wool at least. Since this appears to be a popular request, we will check out how this might best be accomplished. It would also be easy to put the 2nd bell on the second floor.

      Yes the exhaust will actually work better vertically. We have detailed sketchup drawings/plans coming as well.

  7. It is sealed at the top. The inner bell goes all the way to the top. Heat is radiated from the inner bell to the outer bell and to the “skinning material”. Both bells trap gases at the top, only as they cool and sink, do they leave the bell.

  8. Matt Trumble says:

    I’d like to install this over a wood floor. What kind of air gap spacing, insulation, and/or stone base is required for the heater core vs. the bells?

    • The temperatures at the floor are pretty low around 140-160, But I do not know what would be required. I would suggest checking with some of the hearth pad manufacture companies to see what temperatures they protect against.

  9. Doug Kilokowski says:

    My concern is with the height, I have 9′ ceilings and wood floors. By the time I add clearance on the bottom for cooling I’m afraid there won’t be enough room above the first bell. Would shortening both bells by 1′ affect the draw or just raise the exhuast temp?

    • Probably a hearth pad will be sufficient. The temperature on the floor is only the exit temps which are 140-160. The ceiling max is also quite low. 1 ft of clearance should be fine, so I don’t see a problem with 9 ft ceilings.

      But to answer your question, it should not affect the draw only the exit temps.

  10. Dana Lewis says:

    Can this stove be designed linear, 1-2-3-4 instead of 4 section box foot print? My question is if the linear model can work then this design would fit on many existing fire place hearths. I don’t know if making the heater linear would affect its performance or not. Most of the tile flue/bells are exposed on three sides now, the linear would be just two sides on the middle flue/bells and three on the end flue/bells. I have been looking for something like this that can be owner-DIY and still out perform most any modern wood stove and be able to improve in heat out put to wood volume input and get rid of my cast iron wood stove. Also this linear design would spread the load foot print if floor loading is in question.

    • Yes the tower can be lined up. As far as performance a few points. It would not affect heat capture as much as it might tend slow down release magnitude. The towers could be located close to walls, 6″ so they don’t have to be right up against the wall, and still get full radiation. Also, even with the box shape there is some reduced heat radiating surface.

  11. Mark Porter says:

    Would it be possible to combine this with the barrel design with the bells in order to heat the room faster? What would be the drawbacks?

    • SMathieu says:

      The drawback is that the barrel would still be radiating heat after the room had warmed up. Our design lets you wait a little longer for the room to heat up, but the fireclay bricks on the inside of the bells store the heat so that you don’t have to tend the fire all the time. If you get the fireclay bricks warmed up, you can go overnight without lighting a fire.

    • SMathieu says:

      There is only so much heat, but you can use a bell after the barrel to reduce the foot print of the thermal mass storage. People have used a 1/2 barrel turnned on its side longways and covered with cob into a short bench. This provides the benefits of a bell cheaply. So you could do a bell out of flues similarly, but it will not have the same heating storage as the straight castle, since you have put most of your heat into the room already with the barrel.

  12. Bernadette says:


  13. I really like this concept. I am wondering if it would work to add thicker rock/brick to the outside to store additional heat for even longer release? I am sure there are drawbacks to doing this, but the benefits are fairly obvious. I live in a very cold climate (South Central Alaska) and need to provide heat at a higher rate and for longer than your tests were run. I am looking for a setup that will provide 20,000btuh for 12 hours. I was thinking that the longer radiant time could be provided by using 3″ of soapstone on the outside of the flues to capture the heat and hold it longer. I would think that this could be done with a small space between the soapstone and the flues as is done in traditional masonry stoves (Finnish or Russian). That would help reduce stresses between the two materials and let them expand/contract at their own rates. Do you have any experience with this kind of arrangement? Would I need an additional bell to keep the exhaust temps the same or would this suck so much heat out of the system that the exhaust temps would be lower? Am I trying to do too much with a relatively small fire (compared to traditional masonry heaters)?