A plumber is installing a new bathtub/shower combination valve. The manufacturer's instructions specify a minimum water pressure of 140 kPa (20 psi) for proper operation. During rough-in, the static pressure at the incoming water main is 450 kPa (65 psi). What fitting is most likely required to ensure optimal performance and prevent potential damage to the fixtures?

Question: A plumber is installing a new bathtub/shower combination valve. The manufacturer's instructions specify a minimum water pressure of 140 kPa (20 psi) for proper operation. During rough-in, the static pressure at the incoming water main is 450 kPa (65 psi). What fitting is most likely required to ensure optimal performance and prevent potential damage to the fixtures?

Answer options:

• A check valve ✅ A pressure reducing valve (PRV)
• A backflow preventer
• A thermal expansion tank

Correct answer: A pressure reducing valve (PRV)

Explanation: Given the high incoming static pressure (450 kPa) exceeding the fixture's recommended operating pressure (140 kPa), a pressure reducing valve (PRV) is necessary to lower and regulate the water pressure to a safe and efficient level for the fixtures. A check valve prevents backflow, a backflow preventer protects the potable water supply, and a thermal expansion tank addresses pressure increases due to water heating, none of which directly solve the high incoming static pressure issue.