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8" Rocket Masonry Heater Castle Build Kit

  • An 8" Castle Build with an oven sitting immediately on top of the heat riser. In this position, it will get warm enough to cook pizzas. The exhaust goes all around the oven and passes into the 9' tall first bell. This chamber is 24" x 36" and is made using the cutting and stacking pattern shown in images 4 and 5.
  • 8" Dragon Masonry Heater with Heated Bench as the 2nd bell. This is the demonstration system we built outside. The oven is in the second bell and it needs to be in the heat riser stack instead.
  • An 8" Castle Build without an oven. The heat riser chamber can be shorter and use smaller flues than the version with an oven shown in image 1. Otherwise, they are the same build.
  • In order to achieve a 24" x 36" pattern, cuts shown here are made in 24" x 24" chimney flue liners. The next image shows the running bond pattern.
  • This is the running bond pattern for the stack of chimney flue liners. This column is 24" x 36" and is made using 24" x 24" chimney flue liners cut as in the previous image.
  • Here you can see the ceramic blanket for the heat riser, the mineral mesh, the metal top plate for the feed tube, and the ceramic tape for the inside of the first bell.
  • This liquid is sprayed onto the ceramic fiber blanket after it has been put into place. It helps prevent ash buildup.
300.00 LBS
$250.00 (Fixed shipping cost)

Product Description

This kit includes the Dragon Burner and 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 included 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 continous thermal heating of a traditional masonry heater without requiring a large footprint. It can be built in a day with no special skills. Most of the heavy components, the chimney flues and fireclay bricks, can be aquired 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:

  • 8" Dragon Burner with feed tube, burn tunnel, 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 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

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 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 liftgate. We can quote you the exact price with your zip code and these details.


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