F2 code and water temperature overshoots setpoint significantly

Safety first: Turn off power and gas. High water temperature can cause scalding—test water at a faucet before use.

• Verify setpoint: Check the temperature setting on the Giant control. For safety, keep it around 49–54°C (120–130°F) unless higher is required and protected by mixing valves.
• Check for scale: Heavy scale around the sensor can cause delayed response. Drain and flush the tank to remove sediment.
• Inspect sensor mounting: Ensure the tank sensor or thermostat is firmly attached to the tank surface with proper insulation.
• Control board relay: If the heater continues heating after reaching setpoint, the control relay may be stuck closed. This requires replacement of the Giant electronic control board by a technician.