Pentair Challenger Impeller, 3/4 HP Full Rated / 1 HP Up Rated, High Pressure, 355187Z

The Pentair 355187Z is the impeller for the Challenger high pressure pump at 3/4 HP full rated and 1 HP up rated. It also appears under the number 355187, and it is the genuine Pentair part.

What the impeller decides

The impeller is the piece that actually moves the water. Its size and vane shape are what set the flow and the head the pump can produce, which is why impellers are matched to a specific horsepower rating rather than to the pump body. Fitting one that is not cut for your motor gives you a pump that either underperforms or works the motor harder than it should.

When to change it

Two things go wrong. Debris packs into the vanes and strangles flow, which is fixable by cleaning it out. Or the vanes wear down and break, which is not. If the basket is full of water, the filter is clean and the returns are still weak, pull the impeller and look at it.

Do it once

Pentair lists the matching high pressure diffuser, the impeller locking screw, the mechanical seal and a full pump rebuild kit as separate items. Since the pump is already open, it is worth changing the seal and the diffuser at the same time.