Richmond Flow Detection / Demand Signal Failure

Richmond tankless water heater display is on but shows no error; unit does not fire when hot water is demanded.

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.

Possible Causes

Faulty flow sensor, Stuck water control valve, Loose sensor wiring, Extremely low flow rate

Safety first: Standard hot water precautions apply.

Verify demand: Open a hot water tap fully and check the display for flow indication (gpm). If it shows zero, the flow sensor is not detecting flow.
Clean inlet filter: Remove and clean the cold water inlet screen to ensure full flow to the unit.
Service flow sensor: Remove, clean, and if necessary replace the flow sensor as described in the E8 entry.
Check wiring: Inspect and reseat the flow sensor wiring harness at both the sensor and control board.

Medium 3/5

Water Flow Sensor

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