Abstract: A multichamber gas control valve modulates and controls the flow of gas to the burner of an instantaneous water heater. Flow of gas from an inlet chamber to a first chamber of the valve is controlled by a thermostatic valve and gas flow from the first to a second chamber is controlled by a temperature controller. Gas flow from the second chamber to an outlet chamber is controlled by a spring biased valve actuated by a diaphragm actuator operated in response to flow of water through a venturi in the water supply of the heater. The several chambers are in a common valve body closed by a removable cover to provide easy access to the components of the assembly.

Abstract: A venturi operated water flow responsive valve controls the flow of gas to the burner of an instantaneous water heater by controlling the flow of gas between chambers of a main control valve. The venturi operated valve is of the diaphragm type and the gas flow is controlled as a function of water flow rate.