Display shows F2 and heater does not operate, spa may run pumps but water will not heat

Safety first: Turn off power at the breaker before removing the equipment bay panel or touching heater wiring.

• 1. Power cycle: Turn breaker OFF for 5 minutes to allow the heater and sensors to cool. Turn ON and see if F2 clears.
• 2. Verify water level and flow:
  • Ensure water level is above all jets and skimmer opening.
  • Remove and clean filters; try running without filters temporarily.
  • Confirm that the circulation pump is running and that you feel water returning to the spa from the heater return.
• 3. Inspect heater area:
  • With power OFF, locate the stainless steel heater tube in the equipment bay.
  • Check for kinks or closed valves on plumbing entering/exiting the heater.
  • Look for signs of scale or mineral buildup on unions; heavy scale may indicate internal restriction.
• 4. Reset high-limit (if equipped):
  • Some Wellis heater assemblies have a manual reset button on the high-limit; press gently if accessible.
  • If it immediately trips again, do not continue resetting—there is an underlying flow or heater issue.
• 5. If F2 returns quickly: The high-limit sensor or heater assembly may be faulty, or the circulation pump is not providing adequate flow. Contact a qualified spa technician to test sensors, heater resistance, and pump performance.