It’s going to be a while before I get the sun porch done and we can get our rocket mass heater built. In the interim, I must have a less expensive (and quieter) way to stay warm. Toward that end, I’ve been researching sawdust burners. We can get sawdust free if we shovel it.
The premise of the sawdust burner is to use a low/no cost waste material to supply heat in a stove that can be hand built quickly, easily and inexpensively. The plus for me is I can disassemble the stove and cart it outside for the summer months. A 30 gallon barrel of sawdust should burn for about 8 hours. With extra 30 gallon barrels pre-filled with sawdust I can quickly replace a spent barrel with a fully stocked one as needed and filling the barrels outside would keep a good part of the mess out of the house.
In one of my forays on the web I ran across a video of a sawdust burning heater built in England. You can watch the video here. The model in the video is available from British Hardwoods Online for about $500 US. Shipping inside England is about $75 US. In an attempt to get a real clear idea how the stove was built, I did some searching and, through chance, ran across an old open source plan for a “double-drum sawdust stove“. The plans are available (free) online at VITA. Do a search for double-drum sawdust stove and you should find the link.
The design shown in the video is a takeoff (improvement) of the original double-drum sawdust stove design. When comparing the plans to the video, take special note of the difference in location of the single exhaust exit from the outside barrel near the bottom, the lack of damper on the chimney (not needed or advised) and legs instead of a “false floor” in the outside barrel. The inside barrel’s three legs hold it above the ash drawer and allows air to circulate around inside the bottom of the outside barrel facilitating the exhaust up the chimney.
These relatively simple changes improve the performance of the design over the original. With parts and self-labor, this stove, with the aforementioned design changes, can be built for about $100 US. As we build I’ll keep close account of what we spend as opposed to what we can salvage so I can share the result at the end.
Wadly is embracing the task of accumulating the necessary 55 gallon and 30 gallon drums. I will acquire the stove pipe, sheet metal, metal drawer pulls, adhesive and gasket material. In addition I’ll need to buy a 45° and two 90° elbows.
Rather than weld legs on the barrels, I’m going to use three fire bricks to hold the inside barrel off the bottom of the outside drum. I’ll buy (hopefully used) stainless drawer pulls for the handles on the lid and drawer. If I can’t find the pulls I want I’ll build some out of 3/8 mild steel rod. I’ll fold, spindle and mutilate a piece of sheet metal for the drawer and I’ll use the cut-out piece as part of the vent control on the drawer face. I’m a bit fuzzy on this part, but I’ll get there.
I want to be able to install temporary fire proof wall covers for the corner where the burner will rest. I’ve got plenty of fire brick to make a base on which to set the burner. I can mortar them in with a clay/sand mortar which will make them easy to take apart and clean for reuse or I can build a 2×4 fence and set them in place therein.
I’ll supply pics as we build/test/build/test so you can see what works and what doesn’t.