The most likely cause of condenser water pump cavitation is:

• A. A clogged air filter in the building
• B. A faulty cooling tower water level controller
• C. A stuck discharge valve
• D. Too high condensate drain

Answer: (B)

Condenser water pump cavitation occurs when the suction pressure at the pump inlet drops below the water’s vapor pressure, causing vapor bubbles to form and collapse as they move through the impeller. The most likely cause in this loop is a faulty cooling tower water level controller, which can let the tower basin run low or fluctuate and starve the pump of adequate suction head. When the pump isn’t drawing enough water, the inlet pressure falls and cavitation can start.

The other options don’t directly create the low suction condition needed for cavitation. A clogged air filter in the building affects air systems, not the condenser water loop. A stuck discharge valve increases resistance on the discharge side but doesn’t typically lower the inlet pressure to cause cavitation. A too-high condensate drain relates to condensate handling and isn’t a driver of cavitation in the condenser water pump.