Having tried (and failed) to get clay soil cleaned up enough to make smooth clay mortar, I just went out and  bought some clean clay, which was thirty quid well spent, and allowed the burner for the rocket mass heater to get built. Several of you will be wondering what on earth we are conjuring up here, and once again, to save lots of explanation, have a look here.



The ducting is all properly jointed and sealed now, and here you can see the burner built up as far as the top of the fuel feed (right) and the bottom of the riser (left). Building with firebrick and very smooth clay mortar means the joints are very small – down near 1/16″ to keep as much heat in as possible and the fire super efficient.



Here’s the heat riser built up completely, and although the outside looks rough, the inside is all cleaned flush, and super smooth. The next job is to cobble together a metal cylinder to surround the riser and contain some insulation, and mix a load of cob to fill in the void around the burner, and give the outer barrel something to sit on. This may well be double dutch, but it will all make sense soon, don’t worry…