Heater will not start; E03 appears immediately after call for heat

Safety: Turn off power to the heater before opening any panels. Do not run the heater without proper water flow.

• Check pool circulation: Ensure the pool pump is running and primed. Verify that the pump basket is full of water and not cavitating.
• Inspect valves: Confirm that all valves leading to and from the Sta-Rite heater (inlet and outlet) are fully open.
• Clean filter: If system pressure is low or flow is weak, backwash or clean the pool filter. A dirty filter is a common cause of low flow.
• Check pressure switch: Locate the Sta-Rite water pressure switch on the water manifold. Inspect the tubing (if equipped) for kinks or blockages. With power off, disconnect the switch leads and test continuity with a multimeter while the pump is running; it should close (show continuity) when there is adequate flow.
• Adjust or replace switch: Some pressure switches are adjustable; follow the Sta-Rite service manual to fine-tune. If the switch does not close under proper flow, replace the pressure switch.