http://kimmelsteam.com/wetz.htmlWetz started with a down draft wood fired burner patterned after wood gas gasifiers used during WWII inSweden. It is thus top loading and completely controllable. A VW air cooled cooling fan is belt driven and used to pull the exhaust products from the burner through the steamgenerator coils. This controls the extent of the fire and thus steam production. The beauty of having the fire on top of the coils is, first of all ease of loading with fuel, and second of all offering complete protection of the coils from overheat and burning out. When the fan is turned off there is no heat of any kind going to the coils.
The combustion products down draft through a stove pipe and through the center of the coil stack. This means that any ash is left in the ash pan before the combustion products turn around and go up though the coils. The coils are patterned after the Mobile Steam Society Mark II boiler, which had the combustion chamber in the center of the coil stack. It was designed to produce 500 pounds of steam per hour.
The control system is pure John Wetz. He figured out how to control a monotube without using a normalizer/de-super- heater, a problem that Doble never did figure John Wetz Barrel Boilerout to his satisfaction. Wetz used an analogue feedbackloop that used the expansion of hot superheated output steam and the expansion of two tubes from the heat from the fire and the contraction of a tube where cold feed water entered the boiler coil stack to control the feed water. The end result was that the boiler did not flood. The expansion went through a mechanical advantage to operate microswitches to operate solenoids.
This boiler combined good solid fuel combustion design with good monotube boiler design and an improved control system.
Home 