Abstract: A water tank assembly and a heating device are provided. The water tank assembly has a tank body, a main heat exchange pipe assembly and a condenser pipe assembly, and a heat exchange fin assembly. The tank body has a smoke inlet and a smoke outlet. The main heat exchange pipe assembly and the condenser pipe assembly are disposed in the tank body. The main heat exchange pipe assembly has a layer of heat exchange pipes closest to the smoke inlet as a first layer of heat exchange pipes. The heat exchange pipes of the first layer are in communication with each other to form a series of water passageway. The main heat exchange pipe assembly and the condenser pipe assembly at least partially pass through the heat exchange fin assembly.

Abstract: A premixing device for a water heater and the water heater having the same are provided. The premixing device for the water heater has a housing and a turning plate. A first airflow passage, a second airflow passage, a first gas passage and a second gas passage are formed in the housing. The turning plate is rotatably disposed on the housing to adjust an opening degree of the first gas passage and an opening degree of the first airflow passage. An air guide hole directly opposite to the first airflow passage is formed on the turning plate.