E12 — Water flow switch fault (still open)

What does E12 mean?

The boiler's differential water flow switch indicates that there is no water flow when there should be, or it's stuck in an open position.

• Faulty water flow switch.
• Low system water pressure.
• Blockage or air in the heating system preventing water flow.

Click steps to track your progress.

1. 1

   Check the system water pressure on the boiler's gauge. If it's too low (below 0.5 bar), re-pressurize the system.

2. 2

   Ensure all heating controls and external programmers are calling for heat.

3. 3

   If the problem persists, a qualified technician should check the water flow switch.