Heater will not start; display shows SPH1 immediately after call for heat

Warning: High limit trips indicate overheating. Do not repeatedly reset without finding the cause.

• Check water flow: Ensure the pool pump is running at normal speed and the filter is clean. Backwash or clean cartridges if pressure is high.
• Verify valves: Confirm that inlet and outlet isolation valves to the SmartPool heater are fully open and that bypass valves are correctly positioned per the installation manual.
• Inspect for scale: If your water is hard and the heater is older, internal scale may be restricting flow. Look for unusually hot outlet plumbing or frequent SPH1 trips. This typically requires professional descaling of the SmartPool heat exchanger.
• Reset (if manual type): Some SmartPool models have a manual reset high limit on the water header. With power off, remove the front panel and press the red reset button if present. If it trips again, stop using the heater and schedule service.