Display shows A09; water heater indicates circulation pump fault and may stop heating.

Safety first: Turn off power and close isolation valves before opening any pump components. Hot water can cause burns.

This alarm indicates that the internal or connected circulation pump is not providing adequate flow.

• Step 1 – Listen and feel:
  • With power on briefly, listen for pump operation (humming or running sound).
  • If the pump hums but does not circulate, switch power off immediately to avoid damage.
• Step 2 – Vent air:
  • Use the pump’s vent screw to release trapped air.
  • Place a cloth under the screw, open slowly until water flows steadily, then retighten.
• Step 3 – Free the rotor:
  • With power off, remove the pump’s front plug and gently turn the shaft with a screwdriver to free it.
• Step 4 – Check strainers and valves:
  • Ensure isolation valves are open.
  • Clean any inline strainers on the primary circuit.
• Step 5 – Reset alarm:
  • Restore power and clear the A09 alarm.
  • Verify that the pump now runs quietly and that flow temperatures change as expected.

If the pump does not run or trips the breaker, it likely needs replacement.