The mass is complete. It wasn't dry in some of the pictures, which were taken a week ago, but it is pretty much dry now. This top picture was taken this morning.
Some cracking, but I'm going to finish it with tile or something, so it won't matter.
Another view, just so you can get a better idea of the layout.
I really enjoy the arch. I just used a leftover piece of barrel as a form. This is a 10" cleanout and inspection port, the biggest I could fit in the end of a half barrel.
This is what it looks like inside the cleanout. The exhaust snakes back to the end of the bench to force gas flow all the way to the end.
This is a view of the woodfeed. I enlarged it an extra inch during testing. Works really well now, is now capable of thermal runaway if you try hard enough. With normal firewood it is fine, but I am able to overload it using small dense wood well packed, like old barrel staves.
Dimensions are 6 1/2" by 7 5/8" including the P-channel.
Operationally, it works extremely well from what I've read about other's experiences. I have never had to prime the chimney. Draw is exceptional at all times. Maybe even excessive, I don't know without exhaust testing. I feel like it may be running lean.
Starting is very easy, simply stack two handfuls of kindling against the burn tunnel side of the wood feed, propane torch for 30 seconds, then insert firewood. Takes about ten minutes for the chimney to be fully heated and water vapor to disappear. Never smokes back unless I'm goofing with it somehow. No smoke unless burning cold, for instance if the wood is jammed in the feed and hanging off the floor.
I have thermocouples built in, one in the heat riser, one in the bottom of the manifold, and there will be one in the chimney soon and one or more in the mass eventually. Presently, I measure chimney temps with an infrared thermometer. Normal operating temp is around 1000-1500F, but can range from 800-2400 (if overloaded). Final exhaust temperatures range from 130-230, usually 175 +/-.
We have had no problem at all heating our 3700 square foot 2-story house with 2x4 walls, though it's not deep winter. We have been having frost at night, so still somewhat representative. More often that not, my wife now complains of the house being too warm. I have been running one or two loads of wood in the morning, and one in the evening, mostly for fun to dry out the mass.
It's neat to walk in the room in the middle of the day and feel the radiant heat.
I would like, or would have liked to have had a larger bench, but this is the space that was available. This system could definitely handle it and it would make it more efficient. I have been thinking of ideas for a second bell or something connected with pipe vertically out of the bench to draw more heat, maybe like one of those radiant things in the ceilings of outdoor departments at big stores. I wonder how well that would work.
trevor tutt wrote:That thing would eat half of my livingroom.
Depends on your living room. It's three feet wide, four inches from the wall, around 17 feet total length but a lot of that is taken up by the corner, so it's not quite as big as that in terms of mass.
I had intended it to be big enough for a twin mattress, but I don't think that's happening. I need to get the top finished so we can sit on it.