Solar water heater control and protection system

DETAILED DESCRIPTION I claim: 1.
A solar water heater system wherein a collector receives a liquid from a tank through a feed conduit and provides said liquid to said tank through a return conduit, and first and second drain down valves connected to said first and second conduits, respectively, are operable to drain said liquid from said system, comprising: first and second isolating valves respectively situated in said feed and return conduits that isolate said tank from said conduits when said fluid is being drained; a venting valve connected to said collector and to the atmosphere that allows a flow of air therethrough into said conduits and said collector in response to said system being drained; a reversible gear motor; and linkage means for sealing said isolating valves prior to opening said drain down valves and for closing said drain down valves prior to opening said isolating valves.
2.
A valve in accord with claim 1 wherein said linkage means comprising: a cam having a protruding pin; said cam having a coupling to the output shaft of said gearmotor; said isolating valves and said drain down valves each having a rotatable actuating shaft; a first cam follower coupled to said actuating shaft of a first of said isolating valves and having a slot disposed to receive said pin so that said first cam follower can be reversibly driven by said cam; a first arm coupled to said actuating shaft of a second of said isolating valves; a first link coupling said first cam follower and said first arm so that rotation of said first cam follower causes a like rotation of said first arm to thereby actuate both of said isolating valves; a second cam follower coupled to said actuating shaft of a first of said drain down valves and having a slot disposed to receive said pin so that said second cam follower can be reversibly driven by said cam; a second arm coupled to said actuating shaft of a second of said drain down valves; and a second link rotatably coupled to both said second cam follower and to said second arm so that rotation of said second cam follower causes a like rotation of said second arm to thereby actuate both of said drain down valves