The multifunctional controller EU-i-3 is designed to control up to three mixing valves and their pumps in central heating systems. It supports the control of DHW heating, including the Anti-legionella function, and allows for a combination of different operating modes such as weather-compensated control, manual operation, or automatic summer mode. The device can be supplemented with up to two additional units (CS-i-1 or CS-i-1M) to expand up to five heating circuits. It also supports cascade cooperation of boilers and connection to an internet module (WiFi RS, CS-505, or CS-525) for remote monitoring and control.

The controller is compatible with standard ON/OFF thermostats as well as RS thermostats from the TECH brand, including the possibility of registering up to three dedicated thermostats for detailed control of individual valves. The device also provides two voltage-free and two voltage outputs, which can be configured for various applications – such as controlling additional pumps, switching heat sources, or activating devices based on temperature sensors. The equipment includes boiler and return protection, manual operation, solar system control, and cooling support. Software updates are possible via a USB input.