HVACopediaNapoleon · Gas fireplace troubleshooting
Pilot will not stay lit - natural vent
What is going on
Pilot will not hold on a B-vent/natural-vent unit; includes the spill switch circuit.
Likely causes
- Loose thermocouple/thermopile
- Low millivolt output
- Blocked pilot tube/orifice
- Undersized supply line
- Spill switch disconnected or open
- Weak magnet coil
Check in this order
- Check and tighten thermocouple/thermopile connections.
- Test millivolt output (thermocouple 20-30 mV open / 10-15 mV closed; thermopile 500 mV open / min 150 mV closed).
- Remove and clean the pilot tube and orifice.
- Confirm supply line size meets local code.
- Verify the spill switch is connected and has continuity.
- Test the valve magnet coil.
Applies to: Napoleon natural-vent (B-vent) gas fireplaces with spill switch (general service manual flowchart)
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Source: Napoleon (Wolf Steel) Service Manual W415-0118, Part 1-3 Troubleshooting, Pilot Not Holding Flowchart, p.11. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.