Unit attempts to start but quickly shuts down with E03 on the display.

Safety: Turn off the heater before working on pool plumbing. Do not run the heater without proper water flow.

What to check:

• Pool pump and filter: Ensure the circulation pump is running. Clean or backwash the filter. Check pump basket and skimmer baskets for debris.
• Valves: Confirm that the inlet and outlet valves to the Fairland heater are fully open. If a bypass is installed, adjust it so that sufficient flow passes through the heater.
• Air in system: If plumbing was recently serviced, bleed air from high points or open a return line briefly to purge air.
• Flow switch: Locate the Fairland flow switch on the water inlet line (usually a small tee with wires). Inspect for kinks or damage to the cable.

If E03 persists:

• A technician should test and, if necessary, replace the water flow switch and verify correct plumbing configuration and flow rate.