The KTRRB climate controller has been developed especially for air-conditioning systems in 2- or 4-pipe systems with closed when de-energised valves. In this case, the KTRRB is used as a single-room temperature controller with internal sensor or as an external control device with optional remote sensor. The optional external upstream sensor is used for automatic changeover of the controller in heating or cooling mode in 2-pipe operation depending on the inlet temperature; alternatively, this input may be used as a H/C changeover contact. In the event of a sensor failure or short circuit, the heating is controlled with a duty cycle of 30% in order to prevent cooling down or frost damage in the room. Using an internal switch, the existing contact input can be configured as an ECO contact or standby contact. ECO function: When this function is selected, in heating mode the temperature is reduced by 3K and in cooling mode increased by 3K. Standby function: When this function is selected, the controller is switched off (frost protection still active). Surface mounting / wall mounting or using an adapter plate on a flush-mounted socket.