Replies

1. 
   DanH | Dec 27, 2007 07:47am | #1

   Never heard of them. How do they work?

   If your view never changes you're following the wrong leader
1. 
   rlrefalo | Dec 27, 2007 07:00pm | #5

   They appear to be what amounts to a forced down draft wood fired boiler. The combustion air is drawn down toward the coals at the bottom of the wood stack, I would think making it burn hotter , similar to how a forge works, they advertise over 1800 degrees. Supposedly extremely very clean burning and using much less wood. They also make them to burn pellets and corn, even a multi fuel model. Don't know the cost to purchase though, just starting to look. I have an oil fired boiler that heats the domestic and provides water for two fan coils. The house is in central NJ and in my opinion uses way too much oil for about 2500 SF. These boilers could be set up in tandem with the existing boiler to take over most if not all of the heating load,yet the oil boiler would still be there if I let the wood boiler run out of wood. Hopefully someone with real experience can enlighten us.

1. 
   KHWillets | Dec 27, 2007 08:52pm | #6

   I've also been reading about these over on hearth.com. The best description I've found was here: http://en.wikipedia.org/wiki/Jetstream_furnace. Gravity fed, and it applies just enough heat at the bottom of the wood to produce the gas to burn.

2. 
   DanH | Dec 28, 2007 01:03am | #7

   Yeah, that's almost exactly the design from that 70s tractor rig.
   If your view never changes you're following the wrong leader

2. 
   junkhound | Dec 27, 2007 08:03am | #2

   You heat up any solid hydrocarbon and drive off the combustible hydrocarbon gasses. The gasses can then be burned in IC engines and the like.  

   You are left with a coke or charcoal like substance that you can then burn with other technologies, as in wood stove , or continue partial burning to get CO which can also be burned in IC engines.

   Thought about building a gassifier in the back of an old pickup at the time of the '74 oil crunch.  Old technology, French used it in Paris with coal for cars in WWII, so did Germans.

   Biggest problem with IC engines for a wood gassifier is that it has a lot of gums, heads need to be taken off an otto cycle engine probably every 10K miles to clean.

   Had ;never heard of "Tarm", so googled it.  What they do is first burn the gas, the advantage of which is that the heat exchanger for burning a gaseous fuel is more efficient than straight burning.  Looks like they essentially burn the coke then to maintain a preheat on gas combustion gasses.

   Now all they need for 90% efficient is a way to condense the non-combustible volitiles (aka the IC engine gumming up) vs stack ejection of the HHV portion of the fuel. 

1. 
   DanH | Dec 27, 2007 04:28pm | #4

   Yeah, one project I'll probably never tackle is running an engine off of corn, using the same technology. Back during the 70s crisis the DOE hired someone to put together a demo setup on a tractor, using stuff any farmer could find, and burning wood chips. It was an improvement over the old WWII units in that it was a continuous feed vs batch feed. Used a bucket of wood chips to filter the tars out.
   If your view never changes you're following the wrong leader

3. 
   Karl | Dec 27, 2007 08:39am | #3

   I got really excited about the concept last year and liked what I read about the Garn unit. I called up the sales rep and he was very helpful in explaining the details of the unit.

   I haven't spent much time at this site but it looks like a good source of info from people using wood gasification boilers.

   http://www.hearth.com/econtent/index.php/forums/viewforum/21/

   Post back if you learn any good info from your research.

   I liked the concept as we have so much eucalyptus that I hesitate to do any trimming as there is no effective means for us to dispose of the quantities of wood generated. Furthermore our property has three drafty uninsulated turn of the century houses that would cost a fortune to heat with gas or electric. An effective means of heating them with wood would be a great solution to disposing of the excess eucalyptus and keeping the fuel cost under control.

   My only reservation is having a heat source that might baffle my wife or the average houseguest. There is a lot to be said for simplicity. I concluded if I was looking for a project and had the time for one, the boiler would be a good one. Unfortunately I have countless unfinished projects and numerous others that are more pressing than an innovative heat system.

   In their favor the boilers seem to handle larger pieces and burn much cleaner than a residential wood stove.

   Karl