Thermostatic gas flow control means

Claim 1

IN A SYSTEM FOR CONTROLLING THE FLOW OF A COMBUSTIBLE GASEOUS HEATING MEDIUM AT RELATIVELY LOW PRESSURE, A GAS CONDUIT, A VALVE IN SAID GAS CONDUIT, MEANS URGING SAID VALVE TOWARDS ITS OPEN POSITION, AN ELECTRICAL COIL FOR URGING THE VALVE TOWARD ITS CLOSED POSITION, A CURRENT SUPPLY SOURCE FOR SAID COIL, AN ELECTRICAL VALVE IN SERIES WITH SAID COIL FOR MODULATING THE CURRENT THEREIN, A SIGNAL BRIDGE NETWORK HAVING A PAIR OF OUTPUT JUNCTIONS CONNECTED TO SAID ELECTRICAL VALVE FOR CONTROLLING THE CURRENT THEREIN, A SUPPLY SOURCE FOR SAID BRIDGE NETWORK, AT LEAST ONE ELEMENT IN SAID BRIDGE NETWORK BEING A NEGATIVE TEMPERATURE COEFFICIENT RESISTANCE, WHEREBY THE POTENTIAL DIFFERENCE BETWEEN SAID JUNCTIONS MAY BE VARIED, SELECTIVE MEANS FOR CLOSING THE CONNECTIONS BETWEEN SAID SUPPLY SOURCES AND SAID COIL AND BRIDGE NETWORK, AND MEANS FOR REDUCING THE CURRENT TO SAID COIL FOR A PREDETERMINED TIME PERIOD UPON CLOSING OF SAID CONNECTIONS.