E8
Giant
High Limit / Overheat Lockout
E8 displayed, unit locks out and will not restart until power is cycled
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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
Tripped high‑limit thermostat, Excessive scale on heating surfaces, Blocked flue causing heat buildup, Failed circulation in indirect or hybrid models
How to Fix / Troubleshooting
Safety first: Turn off power and gas. Allow the water heater to cool completely. Do not reset repeatedly without finding the cause.
- Reset high limit: Access the thermostat/ECO or high‑limit reset button on the Giant heater (often behind an access panel). Press the red reset button until it clicks.
- Check for scale and sediment: Drain several gallons from the tank drain valve. If water is dirty or contains heavy sediment, perform a full tank flush. Scale can cause localized overheating.
- Inspect venting and airflow: Ensure the combustion air openings and vent system are clear. Blocked vents can cause excessive heat in the combustion chamber.
- Indirect/hybrid circulation: For Giant indirect or hybrid models, verify the circulation pump is operating and that valves are open.
- Service if recurring: If E8 returns frequently, have a technician inspect the burner, flue baffle, and thermostat/ECO assembly for proper operation.
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Repair Difficulty
Hard
4/5
Required Part
Giant High‑Limit Thermostat/ECO
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