Pneumatic temperature control system

Claim 1

A PNEUMATIC TEMPERATURE CONTROL SYSTEM FOR A UNIT VENTILATOR, INCLUDING: A UNIT VENTILATOR HAVING A VALVE CONTROLLING AN AIR CONDITIONING MEDIA FLOW; DAMPER MEANS TO CONTROL A FLOW OF AIR FROM A RETURN AIR PATH AND AN OUTSIDE AIR PATH THROUGH SAID UNIT VENTILATOR TO UTILIZE SAID MEDIA FLOW TO TEMPER SAID AIR FLOW; A PNEUMATIC THERMOSTAT HAVING AN INLET CONNECTED TO A THREE LEVEL SOURCE OF AIR PRESSURE; SAID THERMOSTAT FURTHER HAVING A SUB-MAIN OUTLET AND A CONTROLLED AIR OUTLET; A DUAL PRESSURE TO ELECTRIC RELAY HAVING A FIRST PRESSURE RESPONSIVE SECTION CONNECTED TO SAID SUB-MAIN OUTLET; SAID RELAY MEANS HAVING A SECOND PRESSURE RESPONSIVE SECTION CONNECTED TO SAID CONTROLLED AIR OUTLET; SAID AIR OUTLET CONNECTED TO SAID VALVE AND SAID DAMPER MEANS TO OPERATE SAID DAMPER MEANS AND SAID VALVE; A FIRST AIR PRESSURE FROM SAID SOURCE TO SAID THERMOSTAT INLET OPERATING SAID THERMOSTAT AND SAID RELAY MEANS JOINTLY CONTROLLING SAID DAMPER MEANS SO THAT SAID OUTSIDE AIR PATH IS CLOSED WHILE SAID THERMOSTAT CONTROLS SAID TEMPERED AIR FLOW AT A FIRST TEMPERATURE; A SECOND AIR PRESSURE FROM SAID SOURCE TO SAID THERMOSTAT INLET OPERATING SAID THERMOSTAT AND SAID RELAY MEANS JOINTLY CONTROLLING SAID DAMPER MEANS SO THAT SAID OUTSIDE AIR PATH IS CLOSED WHILE SAID THERMOSTAT CONTROLS SAID TEMPERED AIR FLOW AT A SECOND TEMPERATURE; AND A THIRD PRESSURE FROM SAID SOURCE TO SAID THERMOSTAT INLET OPERATING SAID THERMOSTAT AND SAID RELAY MEANS JOINTLY CONTROLLING SAID DAMPER MEANS SO THAT A MIXTURE OF RETURN AND OUTSIDE AIR FLOWS THROUGH SAID UNIT VENTILATOR WHILE SAID THERMOSTAT CONTROLS SAID TEMPERED AIR FLOW AT SAID SECOND TEMPERATURE.