A. Careless or improperly supplying water to the boiler, improper firing
or allowing steam to vary from high to low pressure, causing unnecessary
expansion and contraction.
52. Q. Does the stopping up of flues affect the steaming capacity of the
engine?
A. Yes; obstructed flues reduce the heating surface, reduce the steaming
capacity of the engine, and, as a rule, result in causing the flues to
leak. They also cause an increase of speed of the gases through the
remaining flues and a poor steaming engine.