Control panel displays OH and spa shuts down; water in the AquaRest spa feels excessively hot, often above 108°F (42°C).

Safety first: Disconnect power at the GFCI breaker before opening any access panels. Extremely hot water can cause burns—do not enter the spa until temperature is safe.

• Step 1 – Verify actual water temperature: Use a separate thermometer to confirm the water temperature. If the display shows OH but water is not actually very hot, suspect a sensor or control issue.
• Step 2 – Remove spa cover and cool the water: Remove the cover to allow heat to escape. Run the jets with the air controls open (if the spa will run) to help cool the water. Do not add ice directly to the shell; use sealed containers if needed.
• Step 3 – Check water level and filters: Ensure the water level is above all suction fittings. Remove the AquaRest filter cartridge from the skimmer/weir housing and run the spa briefly without the filter to see if the OH clears after a reset. A clogged filter can restrict flow and cause overheating.
• Step 4 – Bleed air from the system: If the spa was recently drained/refilled, loosen the union nuts on the pump and heater manifold slightly to let trapped air escape, then retighten. Restore power and see if circulation improves.
• Step 5 – Inspect circulation pump operation: With the equipment compartment open and power restored, verify that the dedicated circulation pump (if equipped) or low-speed of the primary pump is running when the spa calls for heat. If the pump is hot, noisy, or not moving water, it may be failing.
• Step 6 – Reset and test: Turn power off at the breaker for 5 minutes, then back on. If OH returns quickly with normal water temperature, the high-limit sensor or control board heater relay may be faulty and should be tested/replaced by a qualified technician.

Do not bypass safety sensors or relays. If overheating persists, contact a spa technician.