What is the significance of keeping gases above the dew point in air heaters?

Keeping gases above the dew point in air heaters is crucial primarily to prevent moisture condensation. When gases cool down to or below their dew point, water vapor present in the gas will condense into liquid water. This condensation can lead to several problems, including corrosion of the heating surfaces, reduced thermal efficiency, and increased maintenance requirements due to potential damage to the system.

In addition, the presence of moisture can create a favorable environment for microbial growth, which can further compromise system integrity and air quality. By ensuring that the gases remain above the dew point, the air heater operates efficiently without the negative consequences that condensation would bring. Thus, maintaining the temperature of the gases above the dew point is vital for preserving the integrity of the heat exchanger and ensuring reliable operation.