F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements or dispositions of combustion apparatus
F22B31/04—Heat supply by installation of two or more combustion apparatus, e.g. of separate combustion apparatus for the boiler and the superheater respectively
F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
F24H1/22—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating
F24H1/44—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with combinations of two or more of the types covered by groups F24H1/24 - F24H1/40