F24
Saunier Duval
Pump Blocked / No Circulation
Furnace shows F24, rapid temperature rise detected, unit shuts down quickly after start
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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 circulation pump,Airlock in pump or heat exchanger,Blocked system filter,Closed isolation valves
How to Fix / Troubleshooting
Safety first: Isolate power and allow the system to cool. Some water may escape when venting the pump.
- Check valves: Ensure all flow and return isolation valves at the furnace are fully open.
- Vent pump: Remove the pump vent screw and allow air to escape until water appears. Use a screwdriver to gently turn the pump shaft to free it if seized.
- Clean filters: Isolate and clean any system filters or strainers.
- Replace pump: If the pump does not run or seizes repeatedly, replace the pump head or complete pump assembly with a Saunier Duval-approved unit.
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Repair Difficulty
Medium
3/5
Required Part
Circulation Pump
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