A. Combustion chamber

B. Furnace tube sheet

C. Flue gas path

D. Firetube heating surfaces

E. ASME pressure vessel for hot water storage

F. Integral boiler circulating loop (operates during firing cycle only)

G. Condensate drain

H. Induced draft blower for connection to category IV vent

In condensing areas of the boiler, stainless steel components, electroless nickel plating and acid-inert polymers augment the steel pressure vessel.