UV
Raypak Undervoltage Supply Fault

Raypak variable‑speed pump or control shows UV or UNDERVOLT; pump may not start or may run erratically.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loose line connections at pump terminal block, Undersized wiring causing voltage drop, Low utility voltage, Faulty breaker or disconnect

How to Fix / Troubleshooting

Safety first: Turn off power at the main panel before tightening any electrical connections.

  • Measure voltage: With a multimeter and power on (only if you are qualified), measure voltage at the pump terminals while the pump is trying to run. It should be within ±10% of the rated voltage.
  • Inspect connections: Turn power off and remove the Raypak pump wiring cover. Tighten all lugs and ensure no copper is exposed. Check the bonding wire as well.
  • Check wire size and length: Compare installed wire gauge and run length to Raypak installation requirements. Long runs with small wire can cause UV; upgrading wire may be necessary.
  • Test breaker/disconnect: Replace any breaker or disconnect that feels loose, overheats, or shows signs of arcing.
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Repair Difficulty

Medium 3/5

Required Part

Pump Power Wiring Harness
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