Abstract: The present invention provides a solar heater which comprises a water storage tank having a cold water inlet and a hot water outlet, an instantaneous gas fired water heater operatively connected to the hot water outlet of the water storage tank, a first, flow control valve arranged to allow gas to be fed to the gas fired water heater in response to water flow through the hot water outlet, a second, thermostatically controlled valve arranged to allow gas to be fed to the gas fired water heater in response to the temperature of the water in the hot water outlet, and a thermostat arranged to cause the second valve to open when the water in the hot water outlet is at or below a predetermined minimum temperature and to cause the second valve to close when the water in the hot water outlet reaches a predetermined maximum temperature, the arrangement being such that the gas fired water heater is only activated when both the valves are open.