What is the general O2 level guideline for flue gases from atmospheric burning gas appliances?

The general guideline for oxygen (O2) levels in flue gases from atmospheric burning gas appliances typically falls within the range of 6-9%. This range indicates an optimal combustion process, where there is enough oxygen present to ensure efficient burning of gas while minimizing unburned fuel and harmful emissions.

When the O2 level is too low, it can indicate incomplete combustion, resulting in elevated carbon monoxide (CO) and soot production, which are harmful both to health and the environment. Conversely, if the O2 level is too high, as might be the case at levels above 9%, it can suggest that excess air is being supplied, which can reduce the energy efficiency of the appliance. Therefore, maintaining O2 levels in the 6-9% range is essential for safe operation and efficiency in these appliances.

This understanding is pivotal when assessing appliance performance and ensuring compliance with safety and efficiency standards in the field.