A combustion analyzer measures and interprets a number of flue gas parameters to help technicians optimize appliance performance, reduce environmental pollution and maintain safety. The goal of combustion analysis is to ensure that a fossil fuel, like natural gas or propane, burns completely and generates only desirable byproducts. Combustion byproducts like carbon monoxide, sulfur dioxide and nitrogen oxides contribute to acid rain, smog and short-term respiratory problems. The byproducts can be reduced by adjusting appliances, ensuring air-fuel ratio is correct and changing out worn parts.

A typical combustion analyser includes sensors to measure oxygen (O2) and carbon monoxide (CO) in the stack, a thermocouple to monitor temperature and draft pressure, and a sensor to determine flue gas volume. The analyser is typically housed in a portable instrument with a high-contrast display to easily view the results. Some models also feature data-logging functions to store readings.

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Before testing, check the probe, tubing and filters to make sure they are connected and there is no vacuum leak. Using fresh air will avoid contamination of the oxygen and CO sensors, which are sensitive to moisture.

When the analyzer is turned on, it will automatically begin sampling the flue gas and displaying O2 and CO concentrations. The sampled gas is drawn through a water trap and filter assembly, which helps to “condition” the flue gas so it arrives at the sensors in a consistent manner.

The O2 and CO sensors in a combustion analyzer can degrade from being exposed to the air and require periodic calibration. A good quality analyser, like TSI’s CA-CALC combustion analyzer will alert the user when it is time to calibrate.