Viessmann Boiler Repair in Crayford – Boiler Not Firing

We received an urgent call from a homeowner in Crayford whose Viessmann Vitodens boiler had completely shut down. The customer reported that the unit was not firing at all, leaving the entire household without heating or hot water during a particularly cold week. Upon our arrival, the interface screen displayed a persistent burner fault code, indicating that the ignition sequence was failing to initiate. Our engineer performed a preliminary inspection and discovered that while the fan was attempting to run, there was no detectable spark ignition. After checking the flue system for obstructions, we suspected an issue with the printed circuit board (PCB) or a failure in the ignition transformer. It was a stressful situation for the family, so we prioritized a thorough diagnostic process to identify the exact point of failure within the boiler's ignition circuit.

Once the casing was removed, our engineer conducted a multimeter test on the gas valve and the ignition electrode. We discovered that the ignition lead had developed a micro-fracture, which was preventing the high-voltage spark from reaching the burner assembly. This is a subtle fault that often stumps inexperienced engineers, but our team is well-versed in the specific electrical architecture of Viessmann systems. We replaced the damaged ignition lead and the electrode assembly to ensure a strong, consistent arc. After fitting the new components, we performed a combustion analysis using our flue gas analyzer to verify that the air-to-gas ratio was optimal. We also checked the ionisation current to confirm the flame was being detected correctly. Once we confirmed the boiler was cycling through the heating demand perfectly, we conducted a final gas tightness test to ensure everything was left in a safe, fully operational condition.