Pool heater runs but occasionally shuts down with no code, then restarts later on its own.

Safety first: Turn off power before tightening connections or opening panels.

• Stabilize water flow: Ensure the pump runs continuously during heating and that filters are clean. Adjust bypass to maintain steady flow.
• Check for overheating: Confirm that ventilation around the unit is adequate and that the evaporator coil and fan are clean.
• Tighten terminals: Inspect and tighten main power and control wiring terminals on the terminal block and PCB.
• Review external controls: Check any external timers or pool automation systems to ensure they are not cycling power too frequently.