[ COAL BURNING WARM AIR FURNACES, ] SHEET METAL DUCTS AND FITTINGS FOR WARM AIR AND RETURN AIR DISTRIBUTION SYSTEMS FOR FURNACES, [ WOOD BURNING FURNACES, ] OIL BURNING GRAVITY FURNACES, AUTOMATIC HUMIDIFIERS, [ COAL BURNING WINTER AIR CONDITIONING FURNACES INCLUDING HUMIDIFIERS, ] OIL BURNING WINTER AIR CONDITIONING AIR FURNACES INCLUDING HUMIDIFIERS, CONVERSION GAS BURNERS, GAS FIRED WARM AIR FURNACES FOR NATURAL, MIXED, MANUFACTURED, AND LIQUEFIED PETROLEUM GASES, [ GAS FIRED WINTER AIR CONDITIONING FURNACES INCLUDING HUMIDIFIERS, ] AIR CIRCULATING BLOWERS FOR WINTER AIR CONDITIONING SYSTEMS, [ COAL BURNING WARM AIR FURNACES FIRED BY STOKERS, COAL BURNING WINTER AIR CONDITIONING FURNACES INCLUDING HUMIDIFIERS FIRED BY STOKERS, ] OIL BURNERS OF THE HIGH PRESSURE ATOMIZING TYPE, OIL BURNER NOZZLES, CABINETS FOR WARM AIR HEATING AND WINTER AIR CONDITIONING SYSTEMS IN WHICH THE HEATING SYSTEMS ARE HOUSED, REFRACTORY OIL BURNER POT SETS FOR BURNING OIL IN FURNACES, GAS FIRED ATTIC MODEL FURNACES, VAPORIZING TYPE LIQUID FUEL BURNERS