Jacuzzi pool heater short cycles: starts, heats briefly, then shuts off and restarts frequently.

Safety first: Turn off power before accessing internal components.

Steps to reduce short cycling:

• Check water flow and filter: Ensure the pump is running continuously during heating and that the filter is clean. Restricted flow can cause high limit trips.
• Verify setpoint and sensor: Compare displayed water temperature to an external thermometer. If the heater thinks the water is at setpoint too quickly, the sensor may be misreading and should be tested/replaced.
• Review automation settings: If using pool automation, ensure it is not turning the heater on and off rapidly due to tight temperature differentials.
• Hydraulic review: Confirm that the heater is plumbed per Jacuzzi guidelines and that there is no excessive bypass around the heater.