Error A16, boiler indicates flue blockage or differential pressure fault

Safety: Turn off power and gas. Flue work must comply with local regulations; many tasks require a certified technician.

• 1. Visual external check: Inspect the flue terminal for obstructions (bird nests, leaves, snow). Clear carefully.
• 2. Internal inspection: If safe and accessible, check the flue connections at the boiler for signs of collapse or disconnection.
• 3. Differential pressure sensor: On models with a flue differential pressure sensor, inspect the sensor tubes for blockage or water. Clean or replace tubes as needed.
• 4. Professional flue test: If A16 persists, a full flue inspection and measurement of draft/pressure by an authorised Brötje technician is required. Do not operate the boiler with a suspected flue blockage.