Jandy Short Cycling Operation

Heater starts and runs for a short time, then shuts off and restarts repeatedly (short cycling).

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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

Thermostat sensor placement issue, Flow fluctuations from variable-speed pump, Oversized heater for small body of water, Intermittent safety switch opening

How to Fix / Troubleshooting

Safety first: Turn off power before accessing internal components.

  • Check setpoint: Ensure the water temperature setpoint is not very close to actual water temperature, which can cause frequent cycling.
  • Flow stability: If using a variable-speed pump, set a constant RPM high enough to maintain stable flow while the heater runs.
  • Inspect sensors and switches: Wiggle wiring to pressure switch, high limits, and temperature sensor while the heater is off to check for loose connections that could open intermittently.
  • Professional evaluation: If short cycling persists, a technician should check gas pressure, sensor calibration, and system sizing.
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Repair Difficulty

Medium 3/5
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