11 OIL, GAS AND SOLID FUEL BOILERS, IN PARTICULAR LOW TEMPERATURE OIL-POWERED BOILERS, GAS CONDENSER APPARATUS, OIL AND GAS-POWERED WALL-HUNG BOILERS, LOW TEMPERATURE GAS-POWERED BOILERS, CAST BOILERS, HEATING CIRCUIT PUMPS, OIL AND GAS BURNERS FOR BOILERS, IN PARTICULAR OIL AND GAS BLOWER BURNERS, SOLAR INSTALLATIONS, IN PARTICULAR SOLAR COLLECTORS, STORAGE WATER HEATERS, ELECTRIC WATER HEATERS, INSTANTANEOUS WATER HEATERS, HEAT PUMPS, HEAT EXCHANGERS, VENTILATING APPARATUS, STEAM GENERATORS