Electronic temperature control system

Claim 1

An electronic temperature control mixing valve unit for automatically maintaining the temperature of water at a predetermined temperature from a mix of hot and cold water sources having variable temperatures and pressures, said pressures defining a pressure ratio, comprising at least one valve means having an adjustable valve opening setting for adjusting relative flow amounts of said hot and cold water through the unit to give a desired mix water temperature, detecting means for detecting the temperature of said hot water, said cold water and said mix water and for determining said valve opening setting, said detecting means producing separate signals representative of said hot, cold and mix temperatures and said valve opening setting, calculating means receiving said separate signals and for directly calculating a loop gain in response thereto without first calculating the pressure ratio of said hot and cold water sources and control means for receiving said loop gain and for adjusting said valve opening setting in response to said loop gain.