This controller was specially developed for heating/cooling control in 2-pipe pipe systems for hotels, residential and commercial premises and can control up to 5 valve actuators (normally closed). The KTRTB detects the room temperature with an internal sensor and activates the heating or cooling according to the deviation from the setpoint. The use of a triac as a switching element instead of a relay/bimetal means that there is no switching noise during operation. With an internal switch, the existing contact input can be configured as an ECO contact or standby contact. ECO function: If this function is selected, the temperature is reduced by 3K in heating mode and increased by 3K in cooling mode. Standby function: If this function is selected, the controller is switched off (frost protection is still active). Surface/wall mounting (4-hole mounting on the flush-mounted box).