I was reading about dragon masonry rocket heaters yesterday and their use of "bells" of masonry to harvest heat from the rocket and store it. I have not yet built my mass and am wondering about cutting 4 steel drums in half so they stand ends up (tops and bottoms). Then run the flue from the rocket heater into the first half barrel which would be the hottest, then a short piece of 6" pipe from the bottom of it into the next and so on. Thus only the coolest gases from each half barrel would flow into the next. The hottest air would rise and dissipate into the mass above (6-8" of rock and sand) and between the barrels and again, the coolest gases would flow to the next and so on so the exhaust from the 8th half barrel (the coolest of all) would exhaust to the chimney.
If anyone has tried this arrangement before, I'd love to hear how it worked. If no one has, I'll let you know how mine works when I get it together.
Hi Bruce; The photos max sent you are called the "matt walker 1/2 barrel system" .Using barrels instead of pipe to transfer your heat. Cut the barrels in half lengthwise , cut off all but a small part of what's left from the lid . With an 8" system matt told me that I could put a max of 6 barrels end to end. This creates a huge area for heat to collect. There is also no ash build up issue. Last barrel in line, if necessary, he slides his chimney up & down to compensate for a cold start . I'm planning on using this set up in my shop. A solid clay brick surround placed between two bays should make snow melt off the vehicles and give me a warm place to set parts & tools oh and my butt while I ponder how to fix the darn thing! Using a 6" pipe to connect your 8 vertical barrels may give you draft issues. And I wonder if those exposed barrel tops wouldn't suck your mass heat away sooner. Also do you really want to look at 8, 55 gal 1/2 barrels in your house ?