If a reading shows 12% CO2, what does it indicate?

A reading of 12% CO2 indicates that the combustion process is not achieving complete combustion. In an ideal combustion scenario, fuel burns completely with sufficient oxygen, producing carbon dioxide (CO2) as the primary combustion product. High CO2 levels in exhaust gases generally reflect efficient combustion; however, a level of 12% suggests that there isn't enough oxygen available to support the combustion of all the fuel.

When there is incomplete combustion, it means not all of the carbon in the fuel has converted to CO2. Instead, some of it may produce carbon monoxide (CO) or unburned hydrocarbons. This scenario typically points to insufficient air supply or an incorrect fuel-to-air ratio. An optimal CO2 reading for complete combustion is usually higher, generally above 12%, depending on the fuel type. Therefore, a 12% CO2 reading is a clear indicator of incomplete combustion, highlighting the need for adjustment in the combustion process to reduce emissions and enhance efficiency.