Patent ID: 7337753

Claim:
A water heater which in use is supplied with water to be heated, in which the supplied water is heated, and which stores heated water to be drawn therefrom, the water heater including: a burner for burning a fuel such as a fuel gas, a combustion products path through which combustion products from the burner flow and transfer heat to the water which is in use supplied to the water heater and which is to be drawn from the water heater, a heated zone where heat within the water heater is available during periods when the burner is not operating, a flue downstream of said combustion products path and including a down flow passage leading to a discharge outlet, the combustion products flowing in use in a downwards direction after entering the flue from the combustion products path through the down flow passage in passing to the discharge outlet, and wherein the down flow passage has a heat transfer wall which transfers heat from the heated zone to gases in the down flow passage when the burner is not operating, thereby promoting a heat trap effect in the down flow passage.