Which device is used to measure the amount of CO2 in flue products?

• A. Combustion Analyzer
• B. CO2/O2 Indicator
• C. Digital Manometer
• D. Flame Sensor

Answer: (B)

Measuring the CO2 in flue gases is a quick way to assess combustion efficiency and how much excess air the burner has. The CO2/O2 indicator is a portable tool designed to sample flue gas and give a direct reading of CO2 concentration, often with an O2 reading as well. This combination lets you see how complete the combustion is and how far you are from the optimal air-to-fuel mix, making it the most direct and efficient way to quantify CO2 in the exhaust.

A combustion analyzer can also measure CO2 and O2, but it’s a broader diagnostic instrument used for in-depth analysis of combustion parameters. The other devices have different purposes: a digital manometer measures pressure, not gas composition, and a flame sensor detects whether a flame is present.