F.83 — Flow and/or return temperature sensor temperature change fault

What does F.83 mean?

When the burner starts, the boiler fails to register a sufficient temperature change at either the flow or return temperature sensors. This indicates a problem with water circulation or sensor positioning.

• Not enough water in the boiler or heating system.
• Flow and/or return temperature sensor is not in the correct position on the pipe.
• Air in the heating system preventing proper water flow.

Click steps to track your progress.

1. 1

   Check the boiler pressure and top up the water if it is below 1.0 bar.

2. 2

   Bleed air from your radiators and heating system.

3. 3

   Press the fault clearance key on the boiler to reset it. If the fault persists, contact Vaillant Service Solutions.