Transformers! Wood Boiler to Rocket Mass

Hi Permies,
I've been lead here via The Survival Podcast, poked around a bit, and thought I'd throw out a question.
The home I purchased about a year ago came with a Tarm Wood Gassification furnace. This indirectly provides heat through the forced hot air system and heats the hot tank as well. We have oil as a backup, but work hard to not hear that oil burner sound kick in (so we barely use any oil in the winter). Problem is, we burn through a lot of wood. Probably a good 4-5 cords so far this winter. I was wondering is there is any way our current system could take advantage of the rocket stove technology and reduce our wood use. So far, the best I can do is start stacking the wood upright to get that rocket type burn. Any ideas would be welcome! Thanks!

Howdy Ben , welcome to permies ! Is this the unit you are talking about?

http://www.youtube.com/watch?v=M4vSEspltuM

If so, Is the unit outside of the house? What is the temperature of the exhaust gasses?
It looks like the recirculation of smoke using a fan is giving a rocket stove like effect. Then they try to capture the heat with water.
In rocket mass heaters we try to run the exhaust out through a cob heat sink and then by the time it exits the house most of the energy we got from burning is stored in the cob and radiates slowly back into the house as needed.
I guess I am wondering how much of the heat from the burn is not used in your unit.

Hi Wyomiles! Thanks for the quick reply. Mine is the Solo Plus- Mark II. It is in the house, in the basement. How would I figure how much heat is not used?

I think it is a good design. Burns real hot nice and efficient. Thats nice, the other half is heat transfer.
The question is, do the smoke cools down enough in the heat exchanger? You can check the temperature of the exhaust pipe.

If the exhaust is cool enough, you cant really do much. And i would put the fuel in the furnace as the manual says, i don't see a benefit in doing otherwise in this case.
What you CAN do is mainly making sure: -You are using dry wood, this can spare a lot of wood in almost any stove. -The heat that you get, get used well. Insulating your home, updating the heating system, so you wont heat spaces that are not used. (do some contact type heating places perhaps?)

As Balint said you can check how hot your exhaust is with a thermometer. I think rocket heaters exhaust tends to be around 100 F if most of the heat is being stored in the cob. Not sure if you could modify the exhaust to go through a cob mass or not. It might change the operation of the stove ? Not enough draft ect. I am no expert just throwing out ideas. Maybe some others will chime in.

Thanks all for the input. Chimney looks to be about 300 degrees when fan is on and fire is active, cools down considerably when fan is off. Had house inspected for efficiency before we moved in (blower door test) and we are pretty good. Just a big space to heat, 2200 sq ft. We close off rooms we are not using and keep it cool, about 58-62 degrees. FYI have a solar hot water tank and PV panels as well, but always trying to squeeze the most out of mother nature!

probably the best way to optimize the Tarm is to lower the temp at which you pull off water; 300F for exit temperature at the stack is pretty good. If your stove has the same innards as the 2000 series, it would be difficult to build much better unless you have the diagnostic capabilities to tune it...