Carbon / soot on glass, logs or firebox

What is going on

Black carbon is being deposited on the glass, logs or combustion chamber. Caused by flame impingement or a blocked air shutter.

Likely causes

• Flame touching (impinging on) the logs or firebox walls
• Air shutter opening blocked with lint or debris
• Over-firing (wrong manifold pressure or orifice)
• Leaking door gasket or vent joints

Check in this order

1. Check that every log sits in its correct position per the log placement diagram.
2. Open the air shutter to give the burner more primary air.
3. Verify input rate measure manifold pressure and confirm orifice size matches the rating plate (NG #35 orifice, propane #51 orifice per parts list).
4. Inspect door gasketing - it must be complete, unbroken and sealing tightly.
5. Check both the 4" and 7" vent liners for holes and confirm every joint is well sealed.
6. On horizontal vent runs, confirm the minimum rise per foot was followed.
7. Clear any lint or obstruction from the air shutter opening.

More gas fireplace guides

• Blower noisy, vibrating or rattling
• Carbon / soot buildup (service flowchart)
• Complete unit shutdown - direct vent
• Complete unit shutdown - natural vent / vent-free
• Delayed ignition of main burner
• Exhaust fumes smelled in room / occupants get headaches