Condensation heating facility control system

A control system for use in a condensation heating facility to control the secondary vapor blanket used to prevent loss of primary vapor. The control system includes a pair of secondary vapor sensors which detect a secondary vapor blanket slightly below and alternatively slightly above a design depth. The sensors are connected to control relays which energize a high rate dispensing pump to build the secondary vapor blanket when it is below the low depth and to energize a low rate dispensing pump when the secondary vapor blanket is between the low depth and the high depth. Additional control is arranged to inhibit dispensing of secondary liquid when the secondary vapor blanket is above the high depth or the primary vapor blanket is below its designed depth or finally during a vapor phase heating cycle where the primary and secondary vapor blankets collapse as a function of heating during the cycle.