Wood Gas Stove.... any advice?

[Jolyon]

Hey all,

at moot 2011 i witnessed a great wood gas stove, sorry i cant remeber who it was that showed me but i do remeber it being made from a paint tin and a dog food can.... and it worked REALLY well, a nice blue flame and a rocket noise!...

Well have spent the day making one and its crap ;-) so what have I done wrong? two cans , holes in bottom of each and a few holes in the top of the inner one. I will try nd pop some pics on here to illistrate..


But in the mean time... any ideas? secrets as to how to make these work really well? anyone who can back it up with some science would be nice ;-~~)

 

[Lister]

holes in bottom of each

My guessing is that there is your problem, you only put a set of holes in the bottom of one and a set of holes in the top of the other (or vice versa), always opposing holes but never 2 sets at the end.

 

[uncleboob]

...spent last summer trying to figure this out- you need to have a really good fit between the two cans that you use otherwise you don't get the woodgas blue flame effect. I think that the size if the flame/ burner holes must be important in the eventual quality of the flame.

...couldn't get mine to work properly either!

cheers

Joab

 

[noonan79]

I'm going to try 1 of these stoves soon so I will let you know how I get on. In the meantime I will keep a close eye on this thread for any more useful tips!

 

[digitracker]

http://www.youtube.com/watch?feature=player_detailpage&v=a8a6ZFisGDM

The above youtube video gives you a good look at how the stove is set up. It might help you figure out what you need to change on your stove to get it working properly again.

 

[Jolyon]

My guessing is that there is your problem, you only put a set of holes in the bottom of one and a set of holes in the top of the other (or vice versa), always opposing holes but never 2 sets at the end.

??

ok this is counter to all the designs I have seen... my understanding is that the burn is from the top drawing the smoke down, the pressure gradient then forces it up around the inner can and re burns it at the top.. dont quite undertand how your design would work?

 

[Seoras]

Hi Jolyon

In 2011 it was my wood gas stove at the Moot. Ian Woodham brought his the year before.

Here are a few pictures of its construction

http://s219.photobucket.com/albums/cc177/seorasgma/Wood Gas Stove/?start=all

Good luck

George

 

[Jolyon]

George your absolutely right it was! i remember it roaring away.... do you have any tips on the hole ratios? ours is kinda working but i have vivid memories of yours being like a little dragonfly... or am i looking though rosie specs?

 

[WildMedic]

If you have a leaky seal between the cans then why not seal it using stove silicone. I bought a tube for £3.80 off evilbay. It was good to 1100 deg. I have used it on a mini tent stove for my polish lavvu, and 2 garden stoves made from an old bin insert and a gas bottle. None of the seals have ever let me down.

 

[uncleboob]

I used clay to pack any obvious air leaks- not as flexible as silicon though- which is brilliant stuff

 

[Teepee]

??

ok this is counter to all the designs I have seen... my understanding is that the burn is from the top drawing the smoke down, the pressure gradient then forces it up around the inner can and re burns it at the top.. dont quite undertand how your design would work?

A top lit updraught stove that is commonly known as a gasifying wood stove ( there are many different gasifying stove types but the bushbuddy type is a top lit updraught gasifier) doesn't draw the smoke down.

A controlled amount of air supplied by the holes in the bottom of the inner can passes upwards through the fuel, turning the wood to charcoal and driving off volatiles (smoke) through the glowing layer of charcoal at the top.

These volatiles are then burnt above the glowing fuel in the preheated air supplied by the top holes in the inner can.

The ratio of Primary air (bottom inner holes) to secondary air ( top inner holes) is critical. To save you much googling, (if its not running on a fan) its 1 parts to 3 ; primary to secondary air. For a fan, its 1 part to 5 exactly.

For further reading on it, google "Tlud stove". Bioenergy lists website is packed with link and designs and also contains the Tlud Handbook in PDF which is also good reading.

There are designs that "suck" the smoke into the outer walls through the bottom holes ( see Worlstove by Nat Mulcahy) but its a world more complicated and you need a full understanding of fluid dynamics and precision engineering to ever get those to work. Best left alone IME.