Abstract: Applicant discloses a thermally actuated valve having a housing, a resilient seat, a thermally conductive piston, a spring fluid seal, and a working material. The housing defines an inlet and an outlet and has two chambers. The seat is adjacent the inlet and the piston is adapted to move towards the seat when a working fluid in the housing warms and expands and away from the seat when a working fluid in the housing cools. By moving away from the seat, fluid flow through the valve is generated. In one application, Applicant's valve acts as a freeze prevention device. In another application, Applicant's valve is used to cool a source of water.