Richmond tankless heater displays E8 and shuts down; may occur during long hot water draws.

Safety first: Turn OFF power and close the cold water supply valve. Relieve pressure by opening a hot water tap.

• Clean inlet filter: Remove and clean the cold water inlet screen or filter. Rinse under running water to remove sand, rust, and debris. Reinstall.
• Locate flow sensor: The flow sensor is usually installed on the cold water inlet manifold. Disconnect its wiring connector and remove the sensor body according to the service manual.
• Inspect and clean sensor: Check the internal turbine or paddle for scale or debris. Rinse with clean water and gently free any stuck parts. Do not use harsh chemicals or tools that could damage the sensor.
• Reassemble and test: Reinstall the flow sensor, restore water and power, and open a hot tap fully. Observe if the unit now detects flow and fires without E8.
• Replace if needed: If the error persists and flow is adequate at fixtures, the flow sensor may be defective and should be replaced with a Richmond-compatible part.