Display shows HL or HLo and spa shuts down or disables heater

Safety: Turn off power at the GFCI breaker before working in the equipment bay.

• Verify water level: Confirm the spa is filled to the recommended level, typically above the highest jet or skimmer opening.
• Clean or remove filters: Take out all filters and rinse thoroughly. For diagnosis, run the spa briefly without filters to see if HL clears (do not operate long-term without filters).
• Check valves: In the equipment bay, ensure all slice valves (gate valves) on suction and return lines are fully open and not partially closed.
• Inspect circulation: With power restored, verify strong flow from the heater return and circulation jets. Weak or no flow indicates a circulation pump or flow restriction issue.
• Bleed air: Loosen pump unions slightly to release trapped air, then retighten once water flows steadily.
• Reset: After correcting flow issues, power cycle the spa. If HL returns, the high-limit sensor may be overly sensitive or failing and should be tested or replaced.

Persistent HL trips after flow corrections usually require a technician to evaluate the circulation pump, heater manifold, and sensors.