20cm J-Tube Rocket Mass Heater in Hogsback South Africa

Seeing as I asked questions here in previous weeks (*1, *2, *3) in preparation for this project, I reckon I should provide a pic and a video of the end result:





The video shows the first test burn, which I started about two minutes after fitting the barrel. There was a lot of very wet cement/mortar in the manifold area and in the bell, and between all brick layers, so the successful test burn is a very good sign. The unit will be left to dry out for about 2 weeks before the first proper big burn.  

*1 https://permies.com/t/163989/Pine-resin-buildup-flue-barrel
*2 https://permies.com/t/163845/Portland-cement-downstream
*3 https://permies.com/t/164212/Short-wall-bell-prevent-direct

David;
Looks great !  Appears to be  burning super for a first burn!
I recognize the moisture coming out from your bricks.
Thanks for sharing!

I'm soon to  build a very similar unit, and I'm thinking about a different capping-of-the-bell approach.

Did it with lintels last time:



Now I'm thinking about ditching the lintels.

Instead of lintels, I'm thinking about placing a layer of chicken wire over the second-last layer of bricks, and securing the chicken wire in place by laying the final layer of bricks over it.

Then to cap, start with an inch of cob that contains a large amount of straw for structural support. That inch of cob sits on the chicken wire. Once that dries, add a  second layer of cob that contains less straw. Final inch, no straw so that the clay-sand makes the final layer air tight.

Any ideas if this will work?