Zodiac pool heater shuts off when the pump speed is reduced on a variable-speed pump.

Safety: Turn off power before adjusting the pressure switch. Do not operate the heater with inadequate flow.

• Increase pump speed: Raise the variable-speed pump RPM during heater operation to meet Zodiac's minimum flow requirements.
• Clean filtration: Backwash or clean filters and baskets to reduce system resistance and improve flow.
• Check bypass: Ensure any heater bypass valve is not diverting too much water away from the heater.
• Adjust pressure switch (if allowed): Following the service manual, make small adjustments to the pressure switch to allow operation at the desired flow, ensuring that the switch still opens when the pump is off.