| F.22 | Safety shutdown: lack of water | If the pump motor is blocked/faulty or disconnected (wiring/PCB), there is no circulation and the control interprets a lack of water. Check the pump start in test P.0, presence of PWM/230 V voltage, and motor continuity/consumption. |
| F.23 | Safety shutdown: excessive temperature variation | A pump without flow (blocked or with reduced power) causes an excessive ΔT flow/return. Check the pump's rotation/speed, bleed air, and ΔT in the heat exchanger; verify PWM/230 V control. |
| F.24 | Safety shutdown: temperature rise too fast | If the pump is stopped or performing poorly, the flow rises very quickly as the water does not circulate. Check the power supply and rotation of the pump and bleed the system; if it does not respond in P.0, replace the pump. |
| F.75 | Pump error, lack of water | Upon start-up, the electronics await a pressure variation when the pump starts; if the motor does not turn or does not generate flow, there is no change and F.75 appears. Check the pump test and pressure change, voltage to the pump, and the condition of the impeller. |