Gas distribution unit and water heater

A gas distribution unit (7, 7A) includes a main flow passage (65) and a plurality of distribution flow passages (66, 67, 68) that branch from the main flow passage (65) and supplies a fuel gas to each of groups of a plurality of nozzles (30). A main body (25) includes a main depressed portion (28) that forms the main flow passage (65), a plurality of depressed portions (32, 33, 34) that form the respective distribution flow passages (66, 67, 68), and fuel gas inlets (42, 43, 44) provided at upstream ends of the respective depressed portions (32, 33, 34) and communicated with the main depressed portion (28). Among the inlets (42, 43, 44), the inlet (42) of the depressed portion (32) corresponding to the group including the largest number of the nozzles (30) is formed to have a diameter larger than diameters of the inlets (43, 44) of the other depressed portions (33, 34), and the inlet (42) having the large diameter is formed to have a thickness (TI) in a center axis direction smaller than thicknesses of the inlets (43, 44) of the other depressed portions (33, 34). 6 1 612 6 13 25, 26-- @ @ @ ~-- -17