In hot tub applications, if the Grundfos pump is installed vertically, water WILL enter where its not supposed to. I speak from experience. They unlike their competition "Laing" HAVE to be horizontal. Experiment with it, install it vertically and its guaranteed to fail within 72 hours. When it fails, remove the wiring cover, then the capacitor retaining clip, and unplug the wiring harness, water will run out of the winding compartment. The pump, once failed, is trash.