F24 error; heater may not detect water flow correctly even when pump is running.

Safety first: Turn off power before adjusting the pressure switch.

• Verify system pressure: Check the filter pressure gauge with the pump running. Very low pressure may indicate pump or suction issues.
• Adjust pressure switch: Locate the water pressure switch on the heater manifold. Following the Aquacomfort service manual, make small adjustments to the set screw so the switch closes only when adequate flow is present.
• Do not over-adjust: Never set the switch so low that it closes with minimal or no flow; this defeats the safety function.
• Replace if needed: If the switch cannot be calibrated properly, replace it with an Aquacomfort-approved part.