8" Rocket Masonry Heater Castle Build Kit

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Product Overview

This kit does includes the specialized components you need to build an 8" Dragon Heater Castle Masonry Heater using chimney flue liners. This approach breaks new ground in rocket mass heater and masonry heater construction. 

The 8" Dragon Burner combustion system burns the wood very efficiently (+90%) at the rate of 60,000-70,000 BTUs per hour. The masonry elements of the design then captures all the heat for slow release. Exit temperatures leave only enough heat for good chimney draft, typically 150°F. Burning for 4-5 hours will provide 13 hours of heat. It provides the continuous thermal heating of a traditional masonry heater without requiring a large footprint. It can be built in two days with no special skills. Most of the heavy components, the chimney flues and fireclay bricks, can be acquired locally, saving shipping costs.

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. It is particularly suitable as a greenhouse heater, shop heater, or other large space.

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 blanket to insulate the flue liner above the top of the heat riser
  • Ceramic blanket coating to strengthen the blanket and help prevent ash buildup
  • Nonflameable non-metallic mesh for tying the stacks of chimney flue liners together
  • Plans and instructions
  • 8" Dragon Rocket Burn Tunnel with feed tube, heat riser, and gaskets

It DOES NOT include:

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

Chimney Flue Liners Required

Build as shown w/ Bench

 20" x 20" x 1'  1
 20" x 20" x 2'  6
 24" x 24" x 1'  1
 24" x 24" x 2'  6
The main bell is 24"x 36". The oven Tower is 16"x 20". The cheapest construction is using the 2 foot pieces. However, these are VERY heavy. You may want to consider paying a bit more and using the 1 ft. sections.

Dual Tower Build

18" x 18" x 2' 9
18" x 18" x 1' 2
20" x 20" x 2' 3



The main bell is 27" x 36" with an 18"x 18" second bell. The 1st bell must be lined with "split" fire bricks. Splits are firebricks that are only 1.25" thick.  This Build is a lot cheaper that the one pictured, primarily due to the use of the smaller cheaper flues. It takes more cutting but the chimney flue bill will be atleast 1/2 the price of the other.


You will need 3 caps, one for each tower of flues. You can purchase premade 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 refractory. You may want to consider still using some of the ceramic blanket 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. 

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.


This item is shipped via LTL freight and the exact price depends on the destination's distance from Houston and the relative size of the town in which you live. It also makes a difference whether the address is residential or commercial and whether or not you need a lift gate. We can quote you the exact price with your zip code and these details.