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F34 FAULT CODE
Glow-worm

Mains Voltage Fault

Medium Severity Engineer Required

The mains supply voltage is outside the acceptable range.

Step-by-Step Fix Guide

  1. Step 1

    Check other electrical appliances in the home

  2. Step 2 Engineer only

    An electrician should test the mains supply to the boiler

Gas Safe Reminder

Work on gas appliances must be carried out by a Gas Safe registered engineer. The steps above cover safe checks a homeowner can perform - any internal component replacement requires a qualified professional. If in doubt, always call an engineer.

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