E11 error and the Amfa4000 reports high inlet pressure or shuts down during regeneration

Safety first: High water pressure can be dangerous. Do not loosen pressurized fittings. Shut off the main water supply before working on plumbing.

• 1. Measure actual pressure: Use a pressure gauge on a nearby tap to confirm static pressure. If above the Amfa4000 maximum (typically around 6–8 bar; check manual), install or service a pressure reducing valve (PRV) upstream.
• 2. Check outlet and bypass valves: Ensure the outlet valve from the Amfa4000 is fully open and the unit is not dead-headed during regeneration.
• 3. Inspect expansion control: On systems with unvented cylinders, verify that an expansion vessel and pressure relief valve are correctly installed and functioning to prevent pressure spikes.
• 4. Reset the unit: After correcting any pressure issues, power cycle the Amfa4000 and clear E11 via the control panel.

If measured pressure is within spec but E11 continues, the internal pressure sensor or control board may be faulty and should be checked by a technician.