Jacuzzi pool heater ignites briefly then shuts down; display shows F2.

Safety first: Turn off electrical power and gas supply before servicing. Allow the heater to cool fully.

Steps to address F2:

• Check water flow: Confirm the pool pump is running at full prime and that all valves to and from the heater are fully open. Clean skimmer and pump baskets.
• Clean or backwash filter: High filter pressure or very dirty cartridges can reduce flow and cause localized overheating. Clean/backwash until pressure returns to normal.
• Inspect plumbing bypass: If there is an external bypass around the Jacuzzi heater, ensure it is not diverting too much flow away from the heater. Follow Jacuzzi’s plumbing diagram for correct valve positions.
• Inspect high limit switches: Locate the high limit switches on the water manifold. Check for loose or corroded connectors. With power off, test continuity at room temperature; an open switch at normal temperature indicates a failed component.
• Descale heat exchanger (advanced): If the heater is older or used with hard water, internal scale can cause hot spots. A professional should chemically descale or replace the heat exchanger as needed.

If F2 recurs after restoring proper flow and verifying switches, schedule service with a qualified Jacuzzi pool heater technician.