Woosh! Metropolis Hunter Stove-Heater conversion part 1 The Chinese Burner

So I light up the Hunter Stove but I didn't put enough kindling tinder on top for the proper burn. At first it was just all smoke since the wood was wet. But then suddenly this loud Woosh! sound kicked in and the gasifier tripler burn was in action! Suddenly there was no exhaust and I was basically making biochar. I closed off the bottom air vent and the thing kept kicking out heat and just heat exhaust out of the chimney.

As the vid from Todd Albi states - you have to rely on faith to know if the Hunter is still burning - but the reason it goes into gasification is because the internal burner is 1200 degrees Fahrenheit - since the fumes are getting burned off through the secondary and tertiary burn chambers.

And so then yesterday I bought duct pipe - and there are three different rows at Menards for duct pipe. At first I was in the double walled insulated and I had bought that for the conversion of the Survivor rocket stove. This time I knew better - or thought I did. I was still in double wall just not insulated. I loaded up on a T-joint and 90 degree elbows, etc. But I didn't want to spend all that money.

Luckily I somehow discovered a whole other aisle of duct pipe that is the single wall steel - and also you have to snap it together. Finally the stuff I wanted and so the total was under $50. But after I hooked it all together - the 30 gauge snapped together for 3 inch. But the thicket 26 gauge would not snap. Part of the snap mechanism was not aligned and the stuff was too thick for that smaller diameter. Luckily they only had one left of those but I had cleared out Menards for the other lighter gauge as well.

So after I hooked up all the duct pipe - I dubbed this contraption, Metropolis! I'll post a photo after I got to Home Depot to see if they have more duct pipe. So it is like alchemy as the fire is circulated down again - to get "under" the fumes so to speak. So then I got some leaks from the duct pipe but I had not connected them real strong - so also the wood was wet and so I never got to gasifier stage.

So then - now I need some more duct pipe - and another 90 degree elbow. So I tried using the 4 inch double walled insulated elbow but it was leaking smoke. So I pushed the duct pipe in better and tried to fix any crimping. Now I need to get 3 more lengths of duct pipe plus an elbow and maybe a shorter piece if possible - to run out of the stove. But I think this contraption will actually work - as I had 80% smoke coming out of the actual duct pipes - at the end, not leaks.

So the question remains if I am getting any back smoke from lack of draft. But I think it is still pushing the smoke up from the stove and when it gets hotter it should push better. So I'll buy aluminum metal duct pipe tape to seal off any more leaks. Then I should be good to go for a final run of my new Metropolis Woosh! stove-heater gasifier.

So the Hunter Stove is said to be "known as a Chinese Burner." Just what is that?

Certain stove designs are, in effect, gasifiers working on the updraft principle: The air passes up through the fuel, which can be a column of rice hulls, and is combusted, then reduced to carbon monoxide by the residual char on the surface. The resulting gas is then burnt by heated secondary air coming up a concentric tube. Such a device behaves very much like a gas stove. This arrangement is also known as a Chinese burner.

So I got that from googling "Chinese burner" - but it's the image that finally really explains how this Hunter stove works.

 I kept wondering where does the secondary burn take place  - and now we see that the carbon monoxide gas is what leaks out to the secondary air chamber on the sides!! And combusts from that hot air on the sides.

Ah so that's how it works. Funny how the Hunter Silverfire website is still not that clear on the image.

So I posted the photo above - I emailed the owner of Silverfire to let him know the results of my experiment. No gasification! Maybe if I had really pushed it with having totally dry wood, and really letting it burn. But even with the air vent fully open on the bottom, with the pot over the top, the chimney effect was not good enough to get the fire really burning.

So I will use the long duct pipes as indirect heat via clay off the sides of the stove and also the chimney. I will increase the chimney effect, and then surround the chimney in clay as well. The back of the stove has to get air flow, obviously, as does the front.