Abstract: Water heating apparatus including: a storage tank for storing heated water, a gas burner assembly for heating water in the tank; the gas burner assembly including: a housing; a gas burner in the housing; at least one passage through the housing; and mounting means for mounting the housing in the tank such that, in use, it is immersed in water within the tank and wherein, when the gas burner is operated, the temperature of the housing rises and heat transfer to the water in the tank occurs and a convection current in the water flows through the at least one passage to thereby increase heat transfer to the water.