Fuel gas heating water heater

The utility model discloses a fuel gas heating water heater which comprises a furnace shell with a combustion chamber. A heat exchanger is arranged in the combustion chamber, the heat exchanger comprises straight heat exchange pipes, a plurality of heat absorbing fins are arranged on the pipe walls of the straight heat exchange pipes at equal intervals, a water inlet side water box is arranged at the water inlet ends of the straight heat exchange pipes, a water outlet side water box is arranged at the outlet ends of the straight heat exchange pipes, the water inlet side water box is provided with a water inlet, the water inlet is directly connected and communicated with the inlet ends of the straight heat exchange pipes in an opening-to-opening mode, a water outlet is formed in the water outlet side water box, and the water outlet is connected and communicated with the outlet ends of the straight heat exchange pipes in an opening-to-opening mode. The inlet ends of the straight heat exchange pipes are directly connected and communicated with the water inlet in the water inlet side water box in the opening-to-opening mode, the outlet ends of the straight heat exchange pipes are directly connected and communicated with the water outlet in the water outlet side water box in the opening-to-opening mode, in this way, a water inlet connecting pipe and a water outlet connecting pipe in a traditional heat exchanger are omitted, the overall structure of the heat exchanger becomes small and exquisite, production cost is saved, and resistance of water in the water boxes is reduced.