1.  Field of the Invention
This invention lies in the field of water control valves.  More particularly, it is concerned with a temperature sensitive valve which will stop the flow of water from a water line when the outdoor temperature is above, and will start the flow of water when the outdoor temperature is below a certain selected temperature. 
2.  Description of the Prior Art
In the prior art fairly complicated and expensive means have been provided, involving in many cases, electrically sensitive temperature sensing means controlling electro-magnetic valves, so that when the outdoor temperature becomes less than a selected value, in the neighborhood of 32.degree.  F., then the valve will open and allow a small trickle of water to flow through the outdoor water line, the motion of the water being sufficient to prevent the freezing of the water in the water line exposed to the cold outdoor temperature.  Because of the expense and complications of these various devices their use is limited and recourse is had to permitting the water to flow through the outdoor water line to be continuous throughout the time that the line is unattended, rather than to permit the flow only when the temperature is below the selected value.