The three-way valve directs flow either to the heating circuit or the DHW tank.
Symptoms
Lukewarm DHW, unexplained space heating during tank charging, or failure to reach setpoint.
Possible causes
Stuck mechanism, actuator failure, incorrect wiring, or incomplete valve travel.
Troubleshooting
Verify the command, actuator position, and actual temperatures in both branches.
Important
The electrical command alone does not prove that the valve has mechanically switched position.
