Saunier Duval No power / electrical supply failure

Water heater does not start at all, no lights or display

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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

Blown internal fuse on PCB, Faulty main on/off switch, Loose power terminal block, Tripped circuit breaker or blown external fuse

How to Fix / Troubleshooting

Safety first: Before opening the appliance, switch off the circuit breaker and verify absence of voltage with a suitable tester. Only qualified persons should work on mains circuits.

Steps:

  • Check external supply: Confirm that the wall socket or fused spur has power and that the breaker or fuse has not tripped.
  • Inspect power cord and plug: Look for damage, burns, or loose connections.
  • Open electrical compartment: Check the Saunier Duval terminal block for tight connections and no signs of overheating.
  • Check internal fuse: Locate the PCB fuse (usually a glass or cartridge fuse). If blown, replace only with the same rating. If it blows again immediately, there is a short circuit that must be diagnosed by a technician.

Warning: Do not bypass fuses or use higher-rated fuses. This can cause fire or PCB damage.

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Repair Difficulty

Medium 3/5

Required Part

Internal PCB Fuse
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