What happens to the efficiency of a furnace if the carbon monoxide levels are too high?

When carbon monoxide levels are too high in a furnace, it indicates incomplete combustion of fuel. This inefficiency in the combustion process means that more fuel is being consumed than necessary to generate the required heat. As a result, not all of the energy from the fuel contributes to heat production; some of that energy is wasted in the form of unburned fuel and harmful gases like carbon monoxide. Consequently, the overall efficiency of the furnace decreases.

High levels of carbon monoxide can also signal other issues, such as poor ventilation or problems with the heat exchanger, which can further contribute to inefficiencies. Therefore, monitoring and maintaining proper combustion conditions is crucial for optimal furnace performance and efficiency.