Jacuzzi pool heater intermittently shuts down with F9; blower may continue to run.

Safety first: Turn off power and gas if you suspect a gas supply issue. Do not attempt to adjust gas regulators yourself unless licensed.

Steps to address F9:

• Verify gas valves: Ensure all manual gas shutoff valves to the Jacuzzi heater are fully open.
• Check other appliances: Note if F9 occurs when other large gas appliances (e.g., spa heater, range, furnace) are running. This may indicate an undersized gas supply.
• Inspect gas line sizing: Compare the installed gas pipe size and length to Jacuzzi’s installation manual. Long runs or small diameter piping can cause pressure drop.
• Call gas professional: A licensed gas technician should measure static and dynamic gas pressure at the heater inlet and adjust or replace the gas regulator or piping as needed.

Do not continue to operate the heater with suspected low gas pressure; improper combustion can damage the unit and create a safety hazard.