water pumps; heating systems comprised primarily of tubes, pipes and pre-assembled manifolds through which cold or low temperature water circulates; refrigerating machines; [ electric clothes drying machines for household purposes; ] heat sinks for use in heating, cooling and ventilating apparatus; boiler machines, namely, heating, steam, waste and gas boiler machines; and steam generators; gas desulfurization installations, namely, gas desulfurization installations comprising desulfurizing b...