6" Rocket Heater Castle Build

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Product Overview

Click here for Rocket Mass Heater Castle Build literature

This kit includes the specialized components you need to build a 6" Dragon Heater Castle Masonry Heater using chimney flue liners. This approach breaks new ground in rocket mass heater and masonry heater construction.  

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.The 6" heat output is similar to 12 medium sized radiators. It can be placed 6" from a wall. 

We have a document (PDF) explaining all the details about this build, available via email upon request.

Dragon Heater Castle Build Kit Includes: 

  • 6" Dragon Rocket Heater cast burn tunnel with feed tube, heat riser, and gaskets 
  • 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

Other Required Components:

  • 6" Dragon Burner combustion system with feed tube, burn tunnel, heat riser, and gaskets
  • Terra cotta chimney flue liners
  • The caps for the stacks of flue liners
  • An ash clean out door
  • Stove/chimney pipe interface
  • Perlite/Vermiculte Insulation

Chimney Flue Liners

 13" x 13" x 1' clay flue liner 5
 13" x 13" x 2' clay flue liner 2
 13" x 18" x 1' clay flue liner 1
 13" x 18" x 2' clay flue liner 2
 18" x 18" x 1' clay flue liner 5
 18" x 18" x 2' clay flue liner 4







You will need 3 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. 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.

1st Bell Cap - This cap is subjected to much less heat than the heat riser cap, but still requires either refractory or stone.

2nd Bell Cap - This is the only cap that can be made from cement.

Painting Caps - The main photo shows caps that were painted with metallic brown hi-temperature paint.

Ash Cleanout

You will need an ash clean out door. Once a season or so you may want to clean out any accumulated ash. The a large ash clean-out door can be located either at the base of the 2nd tower like the one shown in the pictures below on the left. This option allows for a larger clean out door either 8"x12" or even a 12"x12". The one shown in the picture is a 12"x12".

Another option is to place the clean out door in an additional flue that is used for the connection to the chimney like that shown below on the right. The one on the right is a steel plate ash clean out.