Hi,
I am trying to build small portable woodstoves that burn pellets and/or wood chips that I can deploy in my greenhouse for really cold nights without venting them. I am not too concerned about carbon monoxide as no one will be in the greenhouse until after they have burned out and I have a CO detector as well.
To that end, I have built a small model. It consists of an 8" black stove pipe about 12" tall with a hardware cloth screen-cylinder open below the cap at the bottom of the pipe. I fill the pipe with wood pellets, leaving the cylinder in the middle open to allow air from below. I then light it and add a 2' chimney consisting of 6" black pipe. A basic Finnish candle with an added chimney. Once lit, the surface burns quite well and there is no detectable smoke coming out. After a couple of hours though, after all the pellets have carbonized, the flame goes out and as the coals die down the stove starts throwing lots of smoke. This continues for another half hour (or more - not sure), then dies down some more and stops smoking, but continues to throw some heat for many hours afterward.
My guess is that once the coals start to die down, it needs more oxygen. I am not sure the best way to handle it. I have read with rocket stoves, it is important to gradually feed fresh wood to keep the flame going. I know this is not strictly a rocket stove since it is solely batch heating, but it seems to be the simplest way to heat a greenhouse without having to tend a fire.
Does anyone have some suggestions on either how to fix this problem or else another concept for a portable, small, batch heater that will burn for a long time?
Thanks,
Scott
