F9
Certikin
Mains Supply / Frequency / Phase Fault
Heater intermittently shuts down with F9; may coincide with other electrical issues on site.
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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
Incorrect mains voltage to heater, Loose supply terminals in Certikin electrical connection box, Shared circuit with high-load equipment causing dips, Faulty supply breaker or RCD
How to Fix / Troubleshooting
Safety first: Only a competent person should work on mains electrical circuits. Isolate power before opening any covers.
- Check dedicated supply: Confirm that the heater is on a dedicated circuit sized according to Certikin installation instructions.
- Inspect terminals: With power off, open the electrical connection box and check that live, neutral, and earth conductors are firmly clamped with no signs of overheating.
- Measure voltage: Have a qualified electrician measure the supply voltage at the heater while other large loads (pumps, heat pumps) are running.
- RCD/MCB check: Ensure the protective devices are correctly rated and not nuisance-tripping.
- Restart and monitor: After tightening connections and verifying supply, restore power and observe operation.
If F9 persists with a verified stable supply, the control PCB may be misreading the input and require replacement.
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Repair Difficulty
Hard
4/5
Required Part
Certikin electrical terminal block / main control PCB
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