Prepared for: Roger Taylor
Property address: 8a The Ridgeway, Guildford, GU1 2DG
Date: Wednesday, 28th January 2026
Proposal reference: QU2-72
Your Viessmann 200-W boiler is displaying error code F370 intermittently. This fault code indicates a problem with the burner control unit (BCU), which is the electronic brain that manages your boiler's ignition and combustion process.
Fault identified: Faulty Burner Control Unit (BCU)
What's causing this: The BCU's internal electronics are failing, causing intermittent communication errors. When this happens, the boiler shuts down as a safety precaution.
Why it needs repair: Without a functioning BCU, your boiler cannot operate reliably. The intermittent nature of the fault will worsen over time, leading to more frequent breakdowns and eventually complete failure. Replacing the BCU now prevents you from being left without heating and hot water during cold weather.
Work required:
✅ Supply genuine Viessmann Burner Control Unit
✅ Safely isolate boiler electrical supply
✅ Remove and replace faulty BCU
✅ Reconnect all electrical connections
✅ Test boiler operation and verify fault is cleared
✅ System performance verification