Heater and water dispenser

The invention relates to the technical field of water dispensers, and provides a heater and a water dispenser, the heater comprises a heating pipe and a jet flow assembly, and the heating pipe is provided with a liquid inlet port and a liquid outlet port; the jet assembly is provided with a jet cavity, a water inlet and a plurality of jet holes, the water inlet and the jet holes are communicated with the jet cavity, a water passing gap is formed between the outer wall face of the jet cavity and the inner wall face of the heating pipe, and the water inlet faces the liquid inlet port. Wherein the ratio of the total area of all the jet flow holes to the area of the inner wall of the jet flow cavity ranges from 0.94% to 78.35%, and the water passing gap ranges from 1 mm to 5 mm. Liquid flowing out of the liquid flow through the jet flow holes directly exchanges heat with the heating pipe, the heat exchange efficiency of the liquid flow is improved, meanwhile, the liquid flow can be efficiently heated by limiting the hole proportion of the jet flow holes in the jet flow cavity and limiting the water passing gaps, and the heat exchange efficiency of the liquid flow is improved. And meanwhile, the heat exchange coefficient, the Nusselt number and the pressure drop of the heater can be in a better range, so that the pressure drop of the jet flow cavity and the heat exchange efficiency between the liquid flow and the heating wall surface are balanced.