1. CH or DHW settings
2. CH or DHW pump problem
3. Incorrect “Outlet high limit” setting
1. Check if CH and/or DHW setpoint temperature plus off hysteresis exceed “High limit” setpoint – factory setting = 210°F (99°C).
2. See "Inoperative CH or DHW pump" below.
3. Increase “Outlet high limit” setting; maximum setting = 210°F (99°C).
