What is the significance of the Stack Temperature of the Boiler ?

The Stack temperature of the boiler is a very important parameter in Boiler design.  The stack temperature is the temperature of the flue gases when they reach the stack or the chimney.

A low temperature of the stack temperature indicates that little heat is carried away by the flue gases and that the boiler is operating efficiently.  The stack temperature is a very important specification at the time of boiler purchase.

If the temperature is too low, it can result in cold corrosion. 

The Stack temperature will vary with the time of the year as it is also dependent on ambient temperature.