Stationary condensing boiler for heating with the possibility of preparing the control of an external 3-way valve for preparing hot water in an external tank. Patented "Duopass" technology for maximum use of the condensing mode even during hot water heating! Modulating pump, bypass, expansion valve. Self-diagnosis, equithermal regulation, microprocessor, backlit LCD display, efficiency up to 109%, Energy class **** 92/42EEC, NOx emissions class 5 (LowNOX), smooth PID power modulation (1:9), Open Therm communication, control with a 0-10 V signal, freely programmable functions for adapting to application parameters. Energy efficiency class "A". 5-year warranty.