I don't like the "down" on the chimney. I think the same thing could be accomplished without the risk of gas poisoning. How about putting "radiator" fins on the chimney and a small fan blowing across it?
Hi Grand, I would think that the system is sealed to prevent that. You can also have CO2 monitor in the room. It's pretty good at increasing the use of the heat .
Might try a stack robber instead. http://www.northerntool.com/shop/tools/product_200331508_200331508They will take a small electric fan behind them.
Note that he has the standard exhaust still there. It's there for a reason - you can't start the fire in downdrafter mode. Once your fire is drawing well, then you can switch to downdrafting. Of course the trick is knowing when you can do it, but it's pretty obvious if you switch too soon - the stove blows smoke into the room. This works while requiring no electricity, but does need some intelligence and knowledge from the operator.
You are just slowing down the draft and the burn rate. The downdraft pipes would need cleaned fairly regularly, as they are going to build creosote rapidly. Very effective way to scavenge heat tho.
Leave a comment.. Let me know what you think! :)