Abstract: A control valve for limiting the passage of water between a water source and a hot water tank within an automatic control system for water heaters. The control valve contains a sensing means for determining pressure differentials between the hot water tank, the water source and the delivery system. A rod is secured within the control valve housing for limiting the movement of the sensing means when the hot water heater ruptures of leaks. The sensing means also includes a valve seat which acts to control the entrance of water from the water source into the hot water tank. The valve seat defines a leak path which prevents water pressure loss in the hot water tank during a water cooling cycle.

Abstract: A system for isolating a pressurized water source from a pressurized hot water tank when a leak or rupture occurs to the tank. The system includes a connecting line attached between a check valve and a control valve with a diaphragm attached to the control valve body to sense the pressure differential between the water source and the connecting line. Upon a leak or a rupture occurring, the diaphragm completely closes the control valve. The check valve does not allow the hot water from the water heater tank to enter the domestic system when a leak or rupture occurs. The system further allowing cold water to enter the tank when a predetermined temperature is reached or exceeded. The system further allowing for make up of water volume loss in the tank during a cooling cycle.