What is the consequence of too much secondary air in a boiler?

Too much secondary air in a boiler can lead to the wastage of heat, which ultimately reduces the overall efficiency of the system. Secondary air is essential for the combustion process, as it helps in the complete burning of the fuel. However, when there is an excess of secondary air, it can dilute the fuel-air mixture excessively. This dilution means that not all of the heat generated from the combustion process can be effectively captured and used for heating purposes. Instead, excess heat can be lost up the flue or exhaust, leading to conditions where the boiler operates at a lower efficiency than intended. This inefficiency results in higher energy costs and can also lead to other operational issues within the boiler system.