Specifications include, but are not limited to: 1. Water Jacket: a. The water containing section must be of a "Fin Tube" design, having extruded integral fins b. The tubes must terminate into a one piece header. c. There must be no bolts, gaskets or "O" rings in the head configuration. d. There must be access to the front header of the heat exchanger for the purposes of inspection, cleaning or repair. e. The heat exchanger must be mounted in a stress free jacket assembly in order to provide a "free floating design" able to withstand the effects of thermal shock. f. The boiler must bear the ASME "H" stamp for 160 psi working pressure and must be National Board listed. 2. Combustion Chamber: a. The combustion chamber must be sealed and completely enclosed. b. A burner/flame observation port must be provided.