Lochinvar water heater shows E010 and shuts down; may occur during high demand.

Safety: The high limit indicates an overheat condition. Allow the unit to cool completely. Turn off power and close the gas valve before servicing.

Steps:

• 1. Locate high limit: Find the manual reset high limit switch on the tank or heat exchanger outlet. It usually has a red reset button.
• 2. Reset once: Press the reset button firmly until it clicks. Do not repeatedly reset without finding the cause of overheating.
• 3. Check circulation: Ensure any system or recirculation pumps are operating and that valves are open. A failed pump can cause localized overheating.
• 4. Inspect for scale: If the heater is older or in a hard water area, schedule a professional descaling of the heat exchanger and inspection of tank surfaces.
• 5. Verify wiring: Confirm that wires to and from the high limit are tight and not heat-damaged.
• 6. Replace if nuisance tripping: If the high limit trips at normal temperatures, replace it with the correct Lochinvar high limit switch and verify operating temperatures with a thermometer.