UPDATE July 2019: The original heater that featured in this post for a few years did the job, but after a few years of research and builds of other rocket stoves and thermal mass heaters, I realised that what I had built was not an efficient rocket. Much of the heat went straight out the chimney flue, and the flue was undersized in circumference and height, resulting in occasional back-smoking. Having learned my lessons, I constructed a proper thermal mass heater in the gorge plot cabin: LINK!
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This was built in preparation for last Winter, and it’s been working a treat this Winter as well. Would definitely work in a much bigger room. This one cost about R1200 to make. That’s including the base-layer of fire bricks; the fire cement, and the steel flue and brackets.
Takes about 20 minutes to feel a nice amount of heat emanating from the chimney. 90 minutes to get all the bricks real hot. When the fire dies, the bricks keep their heat for 4 to 5 hours, hence the thermal mass part of the appellation. Uses minimal wood. Wood burns horizontally at the bottom of the burn chamber because of the air suction created by the chimney and flue. And no, no smoke comes up from the burn chamber… unless, it seems, when gusts of gale-force wind push smoke back into the chimney, but this has been rare.
Here it is unlit, kinda being used as a bedside table. The glass bottle is on the 3mm steel plate that seals the brick chimney; the little essential-oil burner (sitting on a rock/shell display) is here moved onto the part of the mass heater into which the wood is fed:
Here it is in use; the stone/shell display at the top also heats up, no problems (but don’t forget your cell phone etc. on the plate when the fire’s going!!!):
Here it is being christened; note the side access point for lighting and cleaning; this side access point is also used as a throttle:
Here it is under construction:
No more need for the small gas burner noticeable in the above picture!