Atlantic water heater shows E4 and stops heating; may occur during filling or after maintenance.

Safety: Turn off power before attempting to refill or bleed the heater. Never energize an Atlantic heater with an empty tank.

• Close the electrical supply and open a nearby hot water tap fully.
• Open the cold water inlet valve to the heater and allow water to run until a steady stream (no sputtering air) flows from the hot tap. This ensures the tank is completely full.
• Check the dielectric unions and inlet group for any blockage that could restrict filling.
• If your Atlantic model uses a flow or level sensor, inspect its wiring and connector on the control board. Clean any scale or debris from the sensor body.
• Verify that the heating element is correctly seated with its gasket and not trapping air at the top of the element pocket.
• Once the tank is confirmed full and all air is purged, restore power and clear the error by cycling power or using the reset function on the control panel (if available).