Hello ive been making one of these too but slightly different hole positions ect as im copying the woodgas stove xl as much as possible in that area. I plan to try what might be a usefull addition to your nice build - to seal the lower holes in the outer wall instead of useing alu tape, use rivets of the right size. Mine will also have the upper holes done in this way. To early to tell if rivets are sealing well enough on mine as its not finished, but if it doesnt seal completely ill try smearing a little thermo steel around them. To power 12volts you can get battery holders of 8 AA size and this would provide 12 volts. To lower the fan speed use a holder with less batteries? Can you post some pics and any more helpfull hints from your finished project? Is the insulation enough to stop your fan from melting? Also have you seen this -
http://www.instructables.com/id/Large-portable-wood-gasifier-Campfire-in-a-can/ Might it be possible to build a big one like this but using a catering soup ketle to provide 10 litres of readymade woodgas chamber loveliness?
Hi James,
To be honest, I've sort of knocked this stove design on the head, and left it non fan powered (I just couldn't get hold of the perfect thermoelectric generator for my needs) and didn't want to have a separate power source.
The ali tape on mine was from experimenting with holes further up the combustion chamber when I had insulation in the bottom, my current stove doesn't need these holes.
The insulation I used in the end was rockwool, tightly packed in the bottom, with fireproof plasterboard on top (smeared with fire cement). This plasterboard has to make a good seal, otherwise air from the fan will come through the combustion chamber, instead of up the inner chamber.
The jet holes at the top need to be no bigger than 2mm, otherwise the 'roaring superheat effect' is reduced. (I went through several designs and found 2mm to be the best)
The insulation worked perfectly, causing no damage to the fan in any way. If you are fitting a TEG, then you need to allow room for the heat sink on the back of it.
The final fan powered design had a smaller fan seated between the bottom layers, so it was flush with the bottom (looked really smart, but pointless without the TEG in my opinion)
I since gave that prototype stove away to a good friend, who has used it (non powered), but with the large hole in the base where the fan used to be caused a BIG problem. The heat from the inner chamber, when running at full tilt on small narrow twigs or rattan will burn a crater into whatever it sits on.
If you are making one, then leave out the centre holes as the wood gas ignites here too, lowering the effect from the top ones. I'd only go with a fan powered one if you are happy carrying batteries or can get the right TEG. Otherwise as a non powered stove, they are excellent as is.
Sorry but I don't have any other pictures of the further process of this design, as at the moment I'm still tinkering with an instant boil wood stove using copper pipe and a water bladder.
Best of luck with your stove mate, I'd like to hear how you get on and see some pictures. Be warned, they are addictive. As for the large on, it would be too big for me, I want it to be portable. The concept is the same though.
Finally, you can use these like hobo stoves (fire at base, and build it up) and they still gasify, as well as the inverted downdraft method.
, these stoves incorporate a multi speed fan. It's complicating things but you could fit a variable resistor or something (potentiometer- AKA a volume knob off an old defunct TV ? Audio device) Could be wrong though?
