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Glow Brand · Boiler troubleshooting

Combustion analysis and throttle adjustment

Glow Combi C95 & C140

What is going on

Calibrate burner CO2 at maximum and minimum fire using a calibrated combustion analyzer.

Check in this order

  1. Use a calibrated analyzer that measures CO2 and CO, set for natural gas.
  2. Select 'Hi' in the System Test Menu and run for at least 5 minutes.
  3. Confirm gas line pressure stays within its min and max values.
  4. Insert the analyzer probe fully into the 1/2 inch flue test port in the exhaust vent adapter.
  5. Adjust the throttle screw with a 5/64 inch (2 mm) Allen key or flat screwdriver until CO2 is within Table 10.1 limits. Clockwise lowers CO2; counterclockwise raises it.
  6. Select 'Lo' and check that combustion stays smooth and CO2/CO fall within Table 10.2 limits. Do not adjust further at minimum fire; contact Glow Brand if out of range.
  7. Make sure the test port cap does not leak condensate when refitted, using approved sealant or Teflon tape.

Applies to: C95 & C140

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Source: Glow Brand C95 & C140 installation & operation manual, p. 52-53. 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.