Heatrae Sadia digital water heater displays E08 and shuts down shortly after opening a hot tap.

Safety first: Isolate electrical power before attempting to purge air or open pipework. Hot water and steam can cause burns.

Steps to address E08:

• 1. Confirm water supply: Check that the main stopcock and any local isolation valves to the heater are fully open.
• 2. Bleed air from system: Open the nearest hot tap fully and leave it running until a steady stream of water (without sputtering) flows. On some models, there may be a manual air bleed screw on the heater—follow the manufacturer’s instructions if present.
• 3. Clean inlet filter: Isolate water, remove the inlet filter or strainer, clean debris, and refit.
• 4. Check flow sensor: If the heater still reports E08 despite good flow, inspect and test the flow sensor as described for E01. Replace if faulty.
• 5. Reset and test: Restore power and run a hot tap. If E08 persists, contact a qualified engineer to check internal hydraulics and sensors.