Central Heat Rockets?

Not sure how many folks on here are familiar with the commercial made downdraft gasification wood boilers? They are rockety too, but harvest and disperse the heat in a different way. Seeing these in operation, wondering how much heat is left in the flue that could be harvested by a bench or bell on it's way up the chimney?



There are also very large offerings of the same thing........being used as wood fired boilers for larger buildings, such as schools, offices, etc. Those are fed by wood chips stored in large bins and silos. They even utilize mechanized feed systems to automatically stoke the fire.......all of it controlled by complex systems of  thermostats, sensors, motors, etc.

Studying those systems, the one thing they have that I believe has merit that might port over to our smaller, simpler system, is the use of the wood chips or chunks, stored in a bin or silo. Wood chunks about the size of tennis balls. At that size, ought to gravity feed into J tubes, etc, yet still allow air to flow thru the chunks.

As one who grew up in midwest, there is such a thing as a corn crib. Many versions, from complex permanent structures, wire frame versions that look like a standard grain bin (with a roof), to simply rings made of snow fence. These chunks would store perfect in any one of them, and can have an automated auger device system to move the chunks into the heated structure.



Wayne Keith...........an Einstein in overalls. They walk amongst us.

On the downdraft wood gasifiaers, here are a couple more examples. Note, these are commercial built units, so somebody has figured out a durable way to handle the excessive heat of combustion. These examples are being used as boilers for domestic and commercial uses, so are many times more complicated than needed as masonry / mass heaters. The key feature I am promoting is the firebox, which is the size of a batch box, and can handle that amount of fuel, but burns like a J-tube.



This next one US made, intended to place outside the home. For those not aware, in US, boilers are considered to be dangerous, and for good reason. Live steam is no joke. Screw up and they will blow up. So they intend for these is to be placed outside and away from the home (what a PITA!), so if it blows up, it only destroys itself. The water these things heat is then piped and pumped thru underground insulated water lines. Heat is extracted at a central furnace, thru in floor radiant heat, or thru in-room radiators or fin tube.

But again, my purpose here is not to promote the hot water systems per se. It is to study the design of the down draft fire box. Can one of those be built and sold as a pre-fab unit to be used as core of a masonry heater? And what is the pre-cast base that is able to survive the heat?



I would also note that when you study these, the really big ones have been so overenginered it borders on the absurd, but they now refer to them not as wood burners, but they burn biomass. Wood chips, reduced to a size they will flow thru the automated systems. But a pound is a pound, and a pound of chips has same btu as a pound of solid wood, it's just more bulk.

Can we move this one to RMH forum also?