HVACopedia

Napoleon · Gas fireplace troubleshooting

Flames always too large or too small / carboning (over- or under-fired)

What is going on

Flame size is consistently wrong and/or carbon forms. The unit is over-fired or under-fired - check gas pressures.

Likely causes

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

Check in this order

  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.

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

More gas fireplace guides

Related

Napoleon error codes · Calculators and reference tables

Take it to the job

All guides, error codes and tips work offline in the HVACopedia app.

Open the app

Source: Napoleon GD70NT-S / GD70PT-S Installation & Operating Instructions W415-0434, Troubleshooting table, p.25; ratings in General Information section. 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.