A16
De Dietrich
3-Way Valve / Diverter Valve Fault
Boiler shows A16, domestic hot water priority fault, DHW not available
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
Stuck 3‑way diverter valve on De Dietrich hydraulic block, Faulty diverter motor, Scale or debris in valve body, Wiring fault to diverter actuator
How to Fix / Troubleshooting
Safety: Turn off power and close water valves before removing any hydraulic components.
Steps:
- Check DHW demand: Open a hot tap and observe the boiler. If it recognises demand but does not heat DHW, suspect the diverter.
- Listen for valve movement: With power on, you should hear the diverter motor move when switching between heating and DHW. If silent, the motor may be faulty.
- Manual exercise: Some valves can be manually moved to free them (consult the service manual). Gently move the actuator to both end positions to break light scale deposits.
- Clean system: Ensure filters are clean to prevent debris from jamming the valve.
Professional help: Diverter valve replacement or motor replacement should be done by a technician to ensure correct sealing and calibration.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
3-Way Diverter Valve
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements