Dunkirk offers the following H20 Series stainless-steel single-coil indirect water heaters for commercial applications. The H20 “I” is available in 80- and 115-gal. capacities with 1” tappings; the H20 “I-H-O” is a high-output indirect in 80- and 115-gal. capacities suitable for use with larger commercial boilers with 1” tappings; and the H20 “H-O-C” are high-output commercial units for use in apartment buildings. “H-O-C” models have a larger heat exchanger to handle more Btu and larger tapping to support higher domestic hot water volume.