Viessmann Overheating Electrical Component

Burning plastic or electrical smell from the water heater casing

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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

Failing circulation pump motor, Overheating fan motor, Loose high-current connection on PCB, Shorted wiring harness

How to Fix / Troubleshooting

Safety: Turn off power immediately. Do not continue to operate the heater until the source is identified.

  • Visual inspection: After cooling, remove the front cover and look for discolored plastic, melted insulation, or burn marks on connectors.
  • Check pump and fan: Smell near the pump and fan motors to localize the odor. If either is excessively hot or noisy, it may be failing.
  • Inspect wiring: Look for wires touching hot surfaces or pinched by panels. Repair or replace damaged wiring.
  • Professional repair: Replace any burnt components and have a technician verify current draw and wiring integrity before restoring power.
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Repair Difficulty

Hard 4/5

Required Part

Circulation Pump
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