Abstract: An explosion proof gas-tired water heater is comprised of a housing having a water reservoir provided with a sealed combustion chamber thereunder. A flue pipe is disposed above the combustion chamber and extends through the reservoir. A gas burner and pilot are provided in the combustion chamber. At least one air supply channel is provided to supply fresh air to the combustion chamber. The air supply channel has an intake disposed a predetermined height above the floor to prevent combustible vapors from entering the combustion chamber. Vapor detectors and/or pressure sensors may be provided as added features to detect the presence of combustible vapors as well as the production of harmful carbon monoxide in the combustion chamber and to actuate the gas supply cut-off valve.