Heater shuts off when pump speed is reduced on a variable-speed pump.

Safety first: Do not operate the heater with inadequate flow.

• Adjust pump speed: Increase the variable-speed pump RPM during heater operation until the heater runs steadily without flow errors.
• Check bypass: Ensure any heater bypass valve is not diverting too much flow away from the heater.
• Pressure switch: If adjustable, have a technician fine-tune the water pressure switch to the correct setting per Jandy specifications.