F12
Nirvana
Mode Valve / External Control Fault
F12 error; heater may start but shuts down when switching between pool and spa modes.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect wiring from automation system, Faulty pool/spa mode sensor, Misconfigured external control input, Defective mode relay on control board
How to Fix / Troubleshooting
Safety first: Turn off power before working on control wiring.
- Check control mode: Verify whether the Nirvana heater is set to internal thermostat control or external automation control. Refer to the user menu.
- Inspect wiring: Open the control compartment and inspect the low-voltage terminal strip where external controls connect. Ensure pool/spa and fireman’s switch connections are tight and correctly landed.
- Automation settings: If connected to a pool automation system, verify that the heater type and mode are correctly configured in the automation controller.
- Mode sensor: Some Nirvana models use a pool/spa mode sensor or switch. Check for proper operation and continuity when switching modes.
- Test standalone: Temporarily disconnect external control wires and set the heater to standalone mode. If F12 disappears, the issue is with external wiring or automation.
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Repair Difficulty
Medium
3/5
Required Part
Nirvana Control Board (Mode Input Circuit)
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