Whirlpool WPSUM50 1/2 HP Submersible Sump Pump

Whirlpool WPSUM50 -- high-capacity protection for flood-prone basements

The WPSUM50 scales up to 1/2 HP for basements with a history of rapid water rise during heavy rain events. At 4,500 GPH, it delivers 50 percent more flow than the WPSUM33 at the same discharge head -- a meaningful difference during the peak flow rate of a 50-year storm event. The stainless steel motor shaft is the key material upgrade over the WPSUM33: in continuous-duty applications where the pump cycles frequently (several times per hour during multi-hour rain events), the stainless shaft resists the surface pitting that eventually causes shaft seal failure in carbon steel alternatives.

Wide float actuation range for large inflow events

The WPSUM50 float activates at 8 inches of water depth and shuts off at 2.5 inches -- a 5.5-inch working range, 1.5 inches wider than the WPSUM33. This wider range is intentional: in a basement experiencing rapid inflow, a shorter actuation range causes the pump to cycle on and off rapidly as inflow closely matches pump output. The wider range allows the pump to run longer per cycle, clearing more water before shutoff and reducing the thermal stress of frequent motor starts.

Upgrade compatibility with WPSUM33 installations

The WPSUM50 uses the same 1.5-inch NPT discharge fitting as the WPSUM33. Homeowners upgrading from a WPSUM33 can reuse all existing discharge piping, the check valve, and the discharge cover at the exterior without modification -- only the pump itself is swapped. This upgrade-in-place capability means no discharge pipe plumbing cost at the time of the pump upgrade.