Poolex pool heat pump will not start; display shows F1 shortly after power-up.

Safety first: Turn off the Poolex pool heater at the disconnect and circuit breaker before opening any panels. Refrigerant work must be done by an F‑gas/EPA-certified technician.

Step-by-step checks (user level):

• Verify water flow: Ensure the pool circulation pump is running and that all valves to and from the Poolex unit are fully open. Low water flow can cause low refrigerant pressure due to poor heat transfer.
• Clean water filter and skimmer baskets: A clogged sand filter or cartridge filter can reduce flow through the Poolex titanium heat exchanger. Backwash or clean filters and re-test.
• Inspect evaporator coil: Remove leaves, dust, and debris from the large finned coil on the air side using a soft brush and low-pressure water spray (from inside out). Do not bend fins.
• Reset power: After improving water and air flow, turn power back on and clear the error by switching the unit off/on from the control panel. Observe if F1 reappears.

Technician-level checks:

• Check refrigerant pressures with gauges to confirm low suction pressure.
• Leak-test the Poolex titanium heat exchanger, service valves, and brazed joints; repair leaks and recharge with the specified refrigerant (e.g., R32/R410A depending on model).
• Test/replace the low-pressure switch or pressure transducer if readings are incorrect.

If F1 returns repeatedly after basic flow and cleaning checks, stop using the heater and contact a qualified pool heat pump technician.