Downdraft wood gassifier stoves.

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zelph
Posts: 15746
Joined: Tue Aug 14, 2007 1:53 pm

Downdraft wood gassifier stoves.

Postby zelph » Tue Sep 02, 2008 9:06 pm

I'm going to try and show that there is no such thing as a downdraft wood gassifier stove. For whatever it's worth. :mrgreen:

I keep seeing this type of stove being made over and over again. The guys that first dubbed this type of stove "downdraft wood gassifier" should have named it top lit wood gassifier as it was recently renamed. Hmmph!!! no doubt they were engineers of some type. Both guys came out with a commercial stove that didn't sell well. Any way I'll start out with a video that shows what burning "gas" should look like when it comes out of the top holes. After viewing the video it seems like I should take some still photos to really get a good look at the burning gas as it comes out of the holes and compare it to what is seen most of the time on web sites.

Image
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

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DarenN
Posts: 2816
Joined: Wed Feb 06, 2008 11:46 am
Location: Surrey, B.C. Canada

Re: Downdraft wood gassifier stoves.

Postby DarenN » Tue Sep 02, 2008 9:29 pm

yep.

when my shop tried to burn down a couple years ago i asked the firefighters' captain about fire burning downwards. "nope never; convection will not allow; unless it's forced by an outside air source forced into it." now, i personally think that that is an over-simplified explaination. we all know that fresh fuel added below a fire will ignite. the radient heat alone is enough to reach combustion temps. that said; the "down-draft gassifier" is just snake oil. nothing more. a properly designed updraft stove will do better, and do it cleaner and hotter, cause we aren't trying to make the fire do something it doesn't want to do; that is, burn downwards.

Daren.........
"I'd rather be happy than right." Slartibartfast

oops56
Posts: 1920
Joined: Wed Sep 19, 2007 11:31 am

Re: Downdraft wood gassifier stoves.

Postby oops56 » Tue Sep 02, 2008 9:48 pm

DarenN wrote:yep.

when my shop tried to burn down a couple years ago i asked the firefighters' captain about fire burning downwards. "nope never; convection will not allow; unless it's forced by an outside air source forced into it." now, i personally think that that is an over-simplified explaination. we all know that fresh fuel added below a fire will ignite. the radient heat alone is enough to reach combustion temps. that said; the "down-draft gassifier" is just snake oil. nothing more. a properly designed updraft stove will do better, and do it cleaner and hotter, cause we aren't trying to make the fire do something it doesn't want to do; that is, burn downwards.

Daren.........

Have you ever hear a stove sucking air from the door damper its dam hot fire the stove can get red.At one time i had a pot belly stove the bottom ring was cast iron i could get it to a orange
Man play with fire man get burnt

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DarenN
Posts: 2816
Joined: Wed Feb 06, 2008 11:46 am
Location: Surrey, B.C. Canada

Re: Downdraft wood gassifier stoves.

Postby DarenN » Tue Sep 02, 2008 9:58 pm

oops56 wrote:
DarenN wrote:yep.

when my shop tried to burn down a couple years ago i asked the firefighters' captain about fire burning downwards. "nope never; convection will not allow; unless it's forced by an outside air source forced into it." now, i personally think that that is an over-simplified explaination. we all know that fresh fuel added below a fire will ignite. the radient heat alone is enough to reach combustion temps. that said; the "down-draft gassifier" is just snake oil. nothing more. a properly designed updraft stove will do better, and do it cleaner and hotter, cause we aren't trying to make the fire do something it doesn't want to do; that is, burn downwards.

Daren.........

Have you ever hear a stove sucking air from the door damper its dam hot fire the stove can get red.At one time i had a pot belly stove the bottom ring was cast iron i could get it to a orange


yes Oops i've seen it lots of times. but on a woodstove it doesn't matter where the air intake is, it's still an updraft fire. the cooler outside air enters through the damper and immediately falls to the bottom of the stove, and then rises as it is warmed, passes through the fire, and escapes out the chimney as hot flue gas. this is called "convection".

Daren......
"I'd rather be happy than right." Slartibartfast

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zelph
Posts: 15746
Joined: Tue Aug 14, 2007 1:53 pm

Re: Downdraft wood gassifier stoves.

Postby zelph » Thu Sep 04, 2008 6:25 pm

List of downdraft threads for you all to review when you have time. See what folks are building and how they describe them:

http://www.garlington.biz/Ray/WoodGasStove/

http://www.backpackinglight.com/cgi-bin ... 0959/index

http://www.backpackinglight.com/cgi-bin ... gination=1

http://www.backpackinglight.com/cgi-bin ... ad_id=3297

I'll add more to them as I come across them, you can do the same. ;)
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/


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