TAC Xenta 121-FC is an easily programmable controller intended for both 2-pipe and 4-pipe applications, with or without re-heat. It can be configured for use with a multitude of valve actuator types, such as on/off, multistage, increase/decrease, PWM, etc. The controller has different types of fan control and advanced fan control functions, including on/off delays, boosting and conditioning. The sequences for cooling, heating and fan are completely user programmable, allowing for numerous applications. For energy savings the controller has built-in economizer functionality. Use TAC Xenta 121-FC with any TAC STR (1.8 kohm) room unit.