65
Rinnai Water Flow Control or Bypass Valve Fault

Boiler shows error 65; domestic hot water may not be recognized or may not start.

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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.

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Possible Causes

Stuck water control valve, Faulty bypass valve actuator, Wiring fault to water control assembly, Control PCB output failure

How to Fix / Troubleshooting

Safety first: Turn off power and isolate water supply. System water may be hot and under pressure.

  • Check for debris: Remove and inspect any inlet strainers or filters that could restrict flow to the water control valve.
  • Listen for valve operation: With power restored briefly and a hot water demand present, listen for the water control or bypass valve actuating. Lack of sound may indicate a failed actuator.
  • Inspect wiring: Ensure connectors to the water control valve or bypass valve are secure and undamaged.
  • Professional service: Replacement of the water control valve or bypass assembly should be performed by a qualified technician, as it involves draining and refilling the system.
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Repair Difficulty

Hard 4/5

Required Part

Water Control Valve Assembly
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