Unit displays E3 and stops heating; may occur when water demand is high or inlet water is very cold.

Safety: Turn OFF power at the breaker and allow the unit to cool for at least 30 minutes before servicing.

Reset and inspection:

• Remove the front cover of the Eemax heater.
• Locate the manual reset high-limit thermostat (if equipped). It is usually a small round device mounted on the heat exchanger with a red or black reset button.
• Press the reset button firmly until you feel a click. If it immediately trips again, do not continue resetting; find the cause of overheating.
• Check the inlet filter screen and any external inlet filter for debris. Clean to restore proper flow.
• Inspect the heating elements and heat exchanger for heavy scale buildup. If present, perform a descaling procedure using a pump, hoses, and a descaling solution approved for Eemax heaters.
• Verify that all hot water fixtures have properly sized flow restrictors; extremely low flow can cause overheating.
• Check the outlet thermistor wiring and sensor for damage that could cause false high readings.
• Reassemble the unit, restore water and power, and test with a hot water tap. Monitor temperature to ensure it is stable and E3 does not reappear.

If the high-limit continues to trip, the control board may be overdriving the elements or misreading sensors; contact a qualified technician.