Boiler fan running but no ignition: what to check
Quick summary
If the fan runs but there’s no heat/hot water, don’t keep resetting. Record the code and check pressure/condensate basics first.
Safety first
- Smell gas or suspect a leak: ventilate, leave the area, and call 0800 111 999.
- CO alarm sounding or anyone unwell: get fresh air and get urgent help.
- Do not remove boiler covers or attempt internal repairs.
- If the boiler attempts to light repeatedly, stop resetting and arrange a qualified check.
Full checklist: Safety guidance
What to check (in order)
- Take a photo of the display/fault code/symbols.
- Check whether the issue happens on hot water demand, heating demand, or both.
- Check system pressure (sealed systems) and note the cold reading.
- If it’s freezing outside, check for a frozen condensate pipe (common on condensing boilers).
- Reset once only and observe: does it attempt ignition, then stop and show a code?
What the result means
- Only fails on one mode: helps narrow DHW vs CH control path.
- Repeated attempts then lockout: ignition/flame-sensing/airflow sequence issues (code-dependent).
- Freezing weather + condensate symptoms: likely frozen/blocked condensate route.
What you can safely do
- Take a photo of any fault code or warning symbol.
- Check whether the issue happens on heating, hot water, or both.
- Listen for the sequence: fan, clicks, then lockout.
- Reset once only if there are no danger signs and the manual allows it.
When to call a professional
- Any gas smell/CO alarm/unsafe signs.
- Repeated lockouts or recurring codes.
- You’re unsure how to interpret the code sequence.
Engineer notes
Sequence-of-operation approach: demand present → fan → APS/proving → ignition → flame proving. Use code and timing to locate stage. Check condensate trap/route issues (model dependent), supply voltage stability, and (qualified) gas/combustion parameters. Document runtime-to-fault and whether it’s mode-specific.
Leave a Reply