What is the purpose of controlling total dissolved solids (TDS) in boiler water?

• A. To maximize carryover.
• B. To enhance corrosion.
• C. To avoid carryover and scaling.
• D. To reduce energy input.

Answer: (C)

Controlling total dissolved solids in boiler water aims to keep minerals from concentrating enough to cause problems in the system. When boiler water is heated, dissolved minerals stay behind as the water turns to steam, so their concentration rises. If it becomes too high, those minerals can precipitate as scale on the boiler tubes, which blocks heat transfer, raises tube temperatures, and can lead to premature equipment failure. At the same time, some dissolved solids can be carried with the steam into piping and turbines, causing downstream deposits and damage. Keeping TDS within a safe range, with proper feedwater treatment and controlled blowdown, prevents both of these issues. The other options don’t fit because increasing carryover is harmful, promoting corrosion is undesirable, and the goal isn’t to reduce energy input—preventing scale and carryover actually helps maintain efficiency and reliability.