Zodiac pool heater cycles on and off frequently without maintaining a stable temperature.

Safety: Turn off power before adjusting internal controls or sensors.

• Verify setpoint and differential: Check the heater's thermostat settings. Some models allow adjustment of temperature differential; a very tight differential can cause frequent cycling.
• Check flow consistency: Ensure the pump speed (for variable-speed pumps) is not changing frequently and that valves are not being adjusted while heating.
• Review automation programming: If connected to a Zodiac automation system, verify that schedules and temperature setpoints are not causing rapid on/off commands.
• Inspect temperature sensor location: Ensure the water temperature sensor is properly immersed in flowing water and not near a dead leg or heater outlet where temperature swings are extreme.
• Adjust system design: In cases of severe oversizing, consult a pool professional about flow adjustments or control strategies to reduce cycling.