What is the purpose of a by-pass damper on boilers equipped with an air pre-heater?

A by-pass damper is essential in the operation of boilers equipped with an air pre-heater as it helps regulate the temperature of the combustion air. By allowing some of the combustion air to bypass the pre-heater, the damper can prevent the air from becoming overly hot, particularly during periods when the heat demand is low or when the system is starting up. This temperature control is crucial, as the optimal combustion air temperature ensures that combustion occurs efficiently and reduces the likelihood of issues such as excess nitrogen oxide (NOx) emissions or inefficient fuel usage.

Both efficiency and performance are enhanced by maintaining the appropriate combustion air temperature. This directly impacts the overall thermal efficiency of the boiler. The ability to modulate the air temperature is vital for optimal combustion, ensuring that the combustion process is efficient, consistent, and safe.