In a Category IV LP unit, what is the expected CO2 content when properly installed and operating with 50% excess air?

For a Category IV LP (liquefied petroleum) furnace, the expected CO2 content when operating with 50% excess air typically falls within the range of 10% to 14%. This is primarily due to the combustion characteristics of LP gas, as well as the additional air which aids in complete combustion but also dilutes the concentration of CO2 in the flue gases.

When a furnace is operating with sufficient excess air, it ensures that there is an adequate supply of oxygen for the combustion process. This excess air helps in achieving more complete combustion and reducing the potential for carbon monoxide production. However, the presence of this extra air will also increase the volume of flue gases, resulting in a lower concentration of CO2 compared to less excess air scenarios.

The range of 10% to 14% CO2 indicates efficient combustion, and this is consistent with what would be expected from a properly functioning Category IV furnace, which is designed to operate with condensing efficiency. In contrast, higher concentrations of CO2 would suggest improper combustion conditions, potentially due to insufficient air or improper equipment functioning.