F MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F24 HEATING; RANGES; VENTILATING
F24H FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
9/00 Details
F24H9/12 Arrangements for connecting heaters to circulation pipes
F24H9/13 for water heaters
F24H9/133 Storage heaters