BoilerTroubleshooting2026-02-26
Boiler Fan Running Constantly
A fan that never stops can mean a stuck relay, air-pressure switch or PCB fault.
If your boiler fan runs continuously even when off, a control fault is likely.
Common causes
A stuck fan relay, a faulty air-pressure switch, or a PCB problem can keep the fan running constantly.
What to do
This needs a technician to test the pressure switch, fan and PCB — it shouldn't be left running indefinitely.
Key takeaways
- Constant fan = control fault
- Often the air-pressure switch or PCB
- Needs technician diagnosis
- Don't ignore it
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