The Double Duty is a gas water heater that doubles as a space heater through hydronic heating. It heats water for domestic use and stores it in a triple-tested, glass-lined storage tank. Available in atmospheric or power-vented models, the NAECA-compliant Double Duty offers an input range of 63,000 - 76,000 Btu/hr and 50 - 75 gallon capacities. Standard features include non-CFC foam insulation, an aluminum tank saver anode that protects from the effects of electrolytic corrosion and dielectric nipples that shield the tank from corrosion and provide piping convenience. The Double Duty also features a double wall heat exchanger that separates heating fluid from domestic water and provides a visual alert should a leak occur in either tube.