F14 error appears intermittently; heater may operate but occasionally lock out.

Safety first: Turn off power at the breaker before opening the electrical compartment. Only qualified persons should work on line voltage.

• Inspect power connections: Remove the electrical access cover and check the line (L1/L2) terminals on the Nirvana power block. Tighten any loose screws and look for discoloration or heat damage.
• Check breaker and wiring: Verify the heater is on a dedicated circuit with the correct breaker size and wire gauge per the installation manual.
• Measure voltage: With power on (exercise caution), measure incoming voltage at the heater and compare to the nameplate rating. Low or fluctuating voltage can cause F14.
• Transformer test: With power off, inspect the Nirvana control transformer. With power on, measure secondary voltage to ensure it is within spec (e.g., 24 VAC). Replace if output is low or intermittent.
• Correct supply issues: If house voltage is unstable, consult an electrician. Persistent F14 after correcting supply may indicate a failing control board.