In the present work, a new freeze protection method is introduced with intended applications for passive solar water heaters. Though electro-thermal wire heat tracing is popularly used to prevent freezing with subsequent risk of burst, this approach is problematic due to resistance heater failure and excessive electric power consumption. In the experimental device, hot water in thermal storage tank is used to heat the outlet pipe from the tank when the surface temperature of the pipe falls lower than a pre-determined set point. The cold water pipe to the thermal storage tank is installed in direct contact with the hot water pipe, controlling its temperature by conduction with the hot water pipe.