A-A-50549 Heaters, Water, Liquid Fuel Oil-Fired, Storage Type, not Exceeding 280,000 BTU/H Input CapacityThis Commercial Item Description covers vertical, light-oil fired, storage-type water heaters having thermal inputs not exceeding 280,000 British thermal units per hour Btu/h 82,040 Watts W and storage capacities up to 100 gallons gal 379 liters L and constructed to Underwriters Laboratories, Inc UL or American Society of Mechanical Engineers ASME requirements.