Solar water heaters

A solar water heater comprising

• (a) a water storage tank having a cold water inlet pipe and a hot water outlet pipe;
• (b) an instantaneous gas fired water heater operatively connected to said hot water outlet pipe and comprising a gas burner;
• (c) a gas supply line to said gas burner;
• (d) means for auto-igniting said gas burner;
• (e) a flow control valve located in said gas supply line and arranged to allow gas to be fed to said gas fired water heater in response to water flow through said hot water outlet;
• (f) a thermostatically controlled valve located in said gas supply line and arranged to allow gas to be fed to said gas fired water heater in response to the temperature of the water in said hot water outlet pipe;
• and
• (g) a thermostat mounted in said hot water outlet pipe downstream of said gas fired water heater and arranged to cause said thermostatically controlled valve to open when the water in said hot water outlet pipe downstream of said gas fired water heater is at or below a predetermined minimum temperature and to cause said thermostatically controlled valve to close partially or completely so as to reduce or eliminate the amount of gas which can flow therethrough when the water in said hot water outlet reaches a predetermined maximum temperature, whereby gas flows to said gas fired water heater only when both said flow control valve and said thermostatically controlled valve are open.