F24
Protherm Water Circulation Fault / Pump Blocked

F24 displayed, furnace stops shortly after starting, noisy circulation

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Seized Protherm circulation pump rotor, Debris in pump housing, Airlock in pump, Incorrect pump wiring or no power to pump

How to Fix / Troubleshooting

Safety first: Isolate power and allow the system to cool. Close isolation valves around the pump if present.

  • Step 1 – Check pump power: When there is a heat demand, verify (with a multimeter, technician only) that the pump is receiving power.
  • Step 2 – Free the rotor: Many pumps have a central screw cap. Remove it carefully (some water may escape) and use a screwdriver to turn the rotor. If stuck, gently free it.
  • Step 3 – Bleed air from pump: With the cap off, allow air to escape until water flows steadily, then refit the cap.
  • Step 4 – Replace pump: If the pump repeatedly seizes or is noisy, replace it with the correct Protherm pump assembly.
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Repair Difficulty

Medium 3/5

Required Part

Circulation Pump
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