WATER HEATERS FOR HOUSEHOLD AND INDUSTRIAL HOT-WATER SUPPLY, CONSISTING OF GAS FIRED INSTANTANEOUS AND STORAGE WATER HEATERS, LIQUID-FUEL-FIRED INSTANTANEOUS AND STORAGE WATER HEATERS, SOLID-FUEL-FIRED INSTANTANEOUS AND STORAGE WATER HEATERS AND ELECTRIC INSTANTANEOUS AND STORAGE WATER HEATERS, HEATING BOILERS FOR HOT WATER SUPPLY; GAS, LIQUIS FUEL, SOLID FUEL, AND ELECTRID BOILERS; RADIATOR ELEMENTS, CONDENSERS, EVAPORATORS, AND PARTS OF SUCH APPARATUSES-NAMELY, PYROPHORIC AND CATALYTIC IGNITORS, WATER-HEATING COILS, PILOT LIGHTS, GAS AND LIQUID FUEL BURNERS, BURNER BLOWERS, CONTROL SYSTEMS FOR AUTOMATICALLY PREVENTING THE BACK FLOW OF WASTE GASES, CONTROL SYSTEMS OPERATED AUTOMATICALLY SHUTTING OFF THE FLOW OF FUEL GAS UPON EXTINGUISHMENT OF THE PILOT BURNER, CONTROL SYSTEMS FOR AUTOMATICALLY SHUTTING OFF THE FUEL SUPPLY UPON LACK OF WATER, AND CONTROL SYSTEMS FOR AUTOMATICALLY SHUTTING OFF FLOW OF FUEL GAS UPON BACK DRAFT OF WASTE GASES; APPATATUS FOR CENTRAL HEATING OF BUILDINGS, BOILERS FOR HOT WATER AND STEAM, AIR CONDITIONING AND VENTILATING APPARARTUS FOR DOMESTIC AND INDUSTRIAL USES