T915C14072 Honeywell Mod Temperature ControllerOverview Proportional (135 ohm) remote bulb controllers for ducts, tanks, boilers, pipes and other heat exchangers. Features Provide proportioning control of three wire, low voltage valve or damper motors. Used to regulate temperatures of either air or liquids. All models ambient compensated. Ambient temperature compensation provides good temperature control. Refer to T775 Electronic Remote Temperature Controller where more exact control is required