F18 displayed, furnace shuts down with electrical smell or no response

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.

Possible Causes

Incorrect live/neutral polarity, Missing earth connection, Voltage outside Glow-worm operating range, Loose mains terminal connections

Safety: Electrical work must comply with local regulations. Isolate the supply before opening the terminal cover.

Technician checks:

Verify live, neutral, and earth connections at the appliance terminal block.
Measure mains voltage and ensure it is within the specified range (typically 220–240 V AC).
Check for signs of overheating or burning at terminals and repair as needed.
Correct polarity and ensure a solid earth connection.

Hard 4/5

Mains Terminal Block / Wiring

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