863 PPH to 17,255 PPH (25 BHP to 500 BHP) up to 85% efficiency
Flex-tube forced draft design offers high fuel-to-output efficiency in a compact, maintenance-friendly design that harnesses natural heat convection to ensure consistent internal heat distribution and complete internal feedwater circulation. The upper steaming chamber is connected to the lower feedwater return vessel via individual serpentine configured carbon steel tubes, to form a 5-pass heat transfer area of 5 sq. ft. per BHP. Separate down-comers connect the upper and lower vessels outside the boiler cabinet to optimize natural circulation and heat transfer.