The design was based around two factors that, along with excellent water circulation, should be appropriate cooling even at light loads.
[5] During World War II a shortage of fuels like gas and petrol alongside the idea of running diesel engines with Steam occurred and led to the development of a new type of boiler.
[6] Dr. Henrich Vorkauf came up with the first design of a new natural circulation boiler which was then installed into a truck in the year 1944.
The rest amount of water flows through the unheated return tubes (1) and downcomers (7) to the rear wall distributor/header (2).
Due to the water returning from the unheated downcomers (1) a lively circulation takes place .