Temperature controlled instantaneous water heating apparatus

Claim 1

Instantaneous automatic water heating apparatus comprising: a heat exchanger including a water heating tube system comprising a plurality of small tubes; a cold water supply conduit to said water heating tube system for supplying thereto water to be heated; a hot water conduit connected to said water heating tube system for reception of heated water therefrom; said small tubes having substantially the same total flow capacity as the respective cold water supply conduit and the hot water conduit; a gas burner beneath said tube system for heating water flowing through said tube system; a gas supply conduit for said burner; a normally closed primary gas control valve in said gas supply conduit for controlling the supply of gas to said burner; an ignition device for igniting gas from the burner; a secondary gas valve for controlling the flow of gas to the burner, said secondary valve being in series with the normally closed primary gas control valve; thermostatic control means for fully opening said secondary gas control valve upon sensing a temperature and closing said secondary gas control valve to said partly opened position when the temperature sensed is above said predetermined temperature and said primary gas control valve is open; electric circuits for said igniter device, secondary gas control valve, and the thermostatic means; and switch means controlled by pressure in one of said water conduits for controlling the circuits to said igniter device, and opening said primary gas control valve and energizing the thermostatic means.