O₂ trim is an automatic air-fuel ratio correction system based on continuous oxygen measurement in flue gases.
Basic operation
An O₂ sensor measures the actual content and the control system compares the value with the desired target.
Correction
A small adjustment is made to the air supply or air-gas ratio to maintain combustion near the optimal range.
Advantages
It can compensate for changes in air temperature, fuel, or the physical condition of the system.
Limitations
O₂ trim does not correct mechanical faults or poor initial calibration. It must operate on a burner that is already properly adjusted.
