A useful boiler combustion report must show the actual measured conditions, not only a calculated efficiency figure. The report should identify the appliance, fuel, test location, operating state, analyzer configuration and observed flue-gas values. Without those details, readings are difficult to compare at a later service visit and cannot reliably justify adjustment.
Include the operating context with every reading
A combustion report is hard to reproduce without fuel type, burner load, probe location, appliance identity, inspection date, ambient conditions and the instrument serial number. Document any before-and-after adjustments as separate conditions. Avoid labeling a calculated instantaneous flue efficiency as total or seasonal boiler efficiency. For guidance on using the instrument and understanding its limits, see boiler efficiency combustion analyzer testing.
Essential identification fields
Record site location, asset ID, appliance make/model, burner/fuel configuration, service date, technician and analyzer identification. Include the selected fuel setting and whether the instrument uses measured or calculated CO2. When operating modes differ, document each test separately rather than combining results from low and high fire. For an explanation of measured and calculated combustion values, see flue gas analyzer readings.
Measured values and their units
| Report item | Typical unit | Why it matters |
|---|---|---|
| Oxygen (O2) | % volume | Combustion air indication under the recorded condition |
| Carbon monoxide (CO) | ppm, basis stated | Safety-related combustion indicator |
| Flue gas / combustion-air temperatures | °C or °F | Inputs for temperature difference and calculations |
| Draft or pressure if required | Pa or inH2O | Venting or combustion system condition |
| Efficiency / stack loss | % calculated | Model-dependent result requiring the selected method |
A repeatable reporting procedure
- Identify the exact manufacturer-required measurement points and test operating state.
- Confirm analyzer warm-up, sensor status, zeroing or calibration-check procedure.
- Record the sampling position and any known dilution or condensate problems.
- Take readings after the specified stabilization time, documenting significant changes rather than choosing one favorable instant.
- Note alarms, observed faults, adjustments and any stop-work decision.
- Retest after authorized service and distinguish pre- and post-service values.
Hypothetical before-and-after record
Before servicing, an operator records O2 = 5.5%; afterward, O2 = 4.8%. The decrease is 0.7 percentage point. Without CO, draft, temperatures, fuel and burner conditions, this difference cannot prove that combustion improved. Record the complete set of readings against the manufacturer’s targets.
Using a Testo analyzer report
The testo 300 combustion analyzer supports flue-gas and associated service measurements, as well as digital reporting functions. Confirm which sensors are installed and ensure exported results preserve units, test status and calibration information. A report emailed from an instrument is not automatically a valid regulatory certificate.
Reporting limits
Do not state that the appliance is safe or compliant solely because a calculated efficiency looks favorable. Appliance servicing, CO faults and venting evaluations require qualified personnel, appropriate safety procedures and governing standards. For related guidance, see Emissions Testing: Measurement Methods and Instruments : NOx measurements.