4" Rocket Heater Castle Build

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$115.00 (Fixed Shipping Cost)
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Product Overview


Aspen Colorado

This kit includes the Dragon Burner and specialized components you need to build a 4" Dragon Heater Castle Masonry Heater using chimney flue liners. This approach breaks new ground in rocket mass heater and masonry heater construction.  The 4" uses only a single bell to minimize the footprint, and reduce overall cost.

Using the dragon burner combustion system it burns the wood very efficiently (+90%) and then captures all the heat for slow release. Exit temperatures leave only enough heat for good chimney draft, typically 150F. Burning for 4-5 hours will provide 13 hours of heat. It provides the continuous thermal heating without requiring a large footprint. It can be built in less than a day with no special skills. Most of the heavy components, the chimney flues can be acquired locally, saving shipping cost.

It has low surface temperatures, similar to a radiator, providing a safer heating option. There is no barrel used, so there are no high temperature metal surfaces. It can be placed 6" from a wall. 

Click here for Rocket Mass Heater Castle Build literature

It Includes; 

  • Steel top plate for feed tube flue
  • Exhaust collar bricks used to form a tunnel between the heat riser flues and 1st bell
  • Ceramic gasket for the slit which needs to be made in each flue liner in the inside of the first bell
  • Ceramic blanket to insulate the flue liner above the top of the heat riser
  • Ceramic blanket coating to strengthen help prevent ash buildup
  • Nonflammable non-metallic mesh for tying the two bells and the heat riser flue liner together
  • 4" Precast Dragon Heater Burn Tunnel with feed tube, heat riser, and gaskets (only 1 more available)

It Does Not Include; 

  • The chimney flue liners
  • The caps for the flues
  • An ash cleanout door
  • Stove/chimney pipe

Chimney Flue Liners 

 13" x 13" x 1' clay flue liner  4
 13" x 13" x 2' clay flue liner  4
 18" x 18" x 1' clay flue liner  2
 18" x 18" x 2' clay flue liner  2

This count includes on 13x13 for a stove pipe exit like shown above. An alternative is to use a square 12"x6" duct adapter.  

 In the picture above the 18x18 flues which are normally used for the bell were not used. Instead the bell was wrapped with recycled brick. The 13x13 flues are the most common and inexpensive. This approach save about $175 of the flue bill.


You will need 2 caps, one for each tower of flues. You can purchase pre-made caps from us or supply your own. 

Heat Riser Cap - This is subjected to the most intense heat of the system, so must be made of suitable materials. Cement is not an option. If you do not wish to use one of our caps, you can use stone or steel. Depending on the stone you may want to consider still using some a ceramic blanket pad to shield the stone from the most intense heat it will reduce thermal stress on any decorative materials used, although it will do so at the expense of reducing the surface temperature. Some users want to keep it hot for emergency cooking.

If you are going to use steel we recommend a thick steel (1/4") to minimize warping and you must use gasket between the flue and the steel. The steel and flue expand at different rates and using mortar only will result in cracking and a poor seal.

Bell Cap - This cap is subjected to much less heat than the heat riser cap, but still requires either refractory or stone.