SunHeater Spa Mode Control / Sensor Fault

Heater will not fire when using spa mode, but works in pool mode

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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

Faulty spa temperature sensor, Incorrect valve actuator position, Misconfigured spa mode settings, Broken spa thermostat knob (analog models)

How to Fix / Troubleshooting

Safety: Turn off power before adjusting wiring or actuators.

  • Check valve positions: Ensure that the pool/spa suction and return valves are correctly directing flow only to the spa when in spa mode.
  • Verify spa sensor: Locate the Spa Temperature Sensor and test its resistance. Replace if open or shorted.
  • Confirm mode settings: On the SunHeater control, verify that spa mode is enabled and that the spa setpoint is above current spa temperature.
  • Test without automation: If using a pool controller, switch to local control and test spa mode directly from the heater. If it works locally, recheck automation programming.
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Repair Difficulty

Medium 3/5

Required Part

Spa Temperature Sensor
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