An industrial appliance such as a floor-mounted or suspended-type warm-air furnace that is larger than 100 ft3 (2. 8 m3) in size, excluding blower compartment, fan compartment, and burner equipment; a steam boiler that operates at pressures that do not exceed 50 psig (gauge pressure of 345 kPa) and is larger than 100 ft3 (2. 8 m3) in size, excluding burner equipment; a water boiler that operates at water temperatures of not more than the temperature of saturated steam at pressures that do not exceed 50 psig (gauge pressure of 345 kPa) and is larger than 100 ft3 (2. 8 m3), excluding burner equipment; a floor mounted or suspended type unit heater larger than 100 ft3 (2. 8 m3) in size, excluding blower compartment, fan compartment, and burner equipment; a commercial cooking range; a bake oven; a candy furnace; a stereotype furnace; a drying and curing appliance; or any other process appliance in which materials are heated or melted at temperatures (excluding flue gas temperature) that do not exceed 600°F (316°C).