Heater shows F16 and will not start; may occur after incorrect wiring or power issues.

Safety first: Turn off power at the breaker and lock it out if possible. Only qualified persons should test live voltage.

• Verify supply voltage: Using a multimeter, confirm that the voltage at the heater’s input terminals matches the nameplate rating (e.g., 120V or 240V).
• Check connections: Tighten all line, neutral, and ground screws in the heater’s junction box. Look for signs of overheating or discoloration.
• Polarity and grounding: Ensure hot and neutral are not reversed and that the unit is properly grounded per Thermeau instructions.
• Inspect internal fuse: Some models include an internal fuse on the control board. Check and replace with the same rating if blown, but investigate the cause of failure.
• Replace control board: If supply power is correct but F16 persists, the board’s internal power supply may be damaged and the board should be replaced.