HL
Evolution Spas High-Limit Sensor Trip / Over-Temperature at Heater

Display shows HL or HLo, spa stops heating and may disable pumps until reset.

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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

Scale buildup inside heater tube, Poor water flow across heater, Faulty high-limit sensor, Heater relay sticking closed on control board

How to Fix / Troubleshooting

Safety: Turn off power at the GFCI breaker before inspecting the heater area.

  • Allow spa to cool: Open the cover and let the water cool down. Do not add cold water directly into the heater area.
  • Clean filter and check flow: Remove and rinse the filter cartridge. Confirm strong water flow from heater return jets when the circulation pump or low-speed pump is running.
  • Inspect heater tube: Look for signs of scale or mineral buildup on the stainless heater tube. Heavy scaling can cause hot spots and high-limit trips.
  • Reset power: After cooling and restoring flow, turn power back on and monitor operation. If HL reappears quickly, the high-limit sensor or heater assembly may need replacement.

Because high-limit issues can be related to electrical faults in the heater relay, contact a qualified technician if basic flow corrections do not resolve the problem.

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Repair Difficulty

Hard 4/5

Required Part

Heater Assembly
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