What can be expected if flue gas temperatures are too low in a fire tube boiler?

If flue gas temperatures are too low in a fire tube boiler, an increase in heat losses is anticipated. When flue gas temperatures drop, it indicates that the combustion gases are not retaining sufficient heat, which means that more energy is being wasted as the gases exit the flue stack.

This loss primarily occurs because the boiler is unable to effectively transfer the heat from the combustion process into the water or steam due to inadequate heat exchange, resulting in inefficient operation. Additionally, low flue gas temperatures can lead to condensation within the flue, which can further exacerbate heat losses and even result in damage to the boiler system over time due to corrosion.

In contrast, overheating or increased efficiency would not be the outcome of low flue gas temperatures. An increase in boiler efficiency typically requires higher flue gas temperatures to ensure optimal heat transfer. Similarly, no effects on the system would conflict with the understanding of how low temperatures can impair performance and lead to inefficiencies.