that it would not be wise to pump cold water into a boiler since that would decrease the
temperature of the water already in the boiler and so reduce the rate at which steam was
being made. Also, the introduction of cold water might set up strains in the boiler by virtue of the great temperature difference. It, therefore, becomes expedient to heat the water to as high a temperature as possible before pumping it into the boiler. So, it is run through a feedwater heater