When placing a shell-and-tube heat exchanger such as a jacket water cooler into service, to insure optimal heat transfer what statement represents the correct operating procedure?

Correct Answer: Option A — Both the water box and shell vent valves should be opened to expel any entrapped air and then reclosed.

Air pockets in heat exchangers act as insulators, significantly reducing the effective heat transfer surface area. Opening vent valves allows entrapped air to escape, ensuring the tubes are fully wetted by the cooling medium. This is essential for maintaining design heat transfer coefficients and preventing localized hot spots.