Napoleon Gas Fireplace: Flames always too large or too small / carboning (over- or under-fired)

Flames always too large or too small / carboning (over- or under-fired) on a Napoleon gas fireplace: Flame size is consistently wrong and/or carbon forms. The unit is over-fired or under-fired - check gas pressures.

Homeowner with a gas fireplace problem? Call (647) 657-2977 or book a service call — licensed technicians across Vaughan and the GTA.

Applies to: Napoleon GD70 STARfire direct-vent fireplace (GD70NT-S natural gas, GD70PT-S propane)

Common causes of flames always too large or too small / carboning (over- or under-fired)

• Inlet gas pressure too high or too low
• Manifold (outlet) pressure out of spec
• Wrong orifice

How to fix flames always too large or too small / carboning (over- or under-fired): step by step

1. Run the main burner on HI before taking readings.
2. Inlet pressure: turn test screw (A) 2-3 turns counter-clockwise and attach the manometer. Spec: natural gas 7" w.c. (min 4.5"), propane 13" w.c. (min 11").
3. Outlet/manifold pressure: same method using test screw (B). Spec: natural gas 3.5" w.c., propane 10" w.c.
4. Correct supply or regulator problems so readings match spec; confirm orifice matches rating plate.
5. After testing, turn both screws clockwise firmly to reseal - do not over-torque.
6. WARNING: leak-test the test points with soap and water solution.

If the unit shows an error code, look it up: Napoleon Gas Fireplace codes

Models

GD70NT-SGD70PT-S