E08
Riello Low Water / Flow Fault

Display shows E08, indicating low water or flow fault on hydronic Riello furnace/boiler

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Safety Warning

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.

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Possible Causes

Low system water pressure, Faulty low water cutoff, Air trapped in system, Circulator pump failure

How to Fix / Troubleshooting

Safety: Turn off power and allow system to cool before opening any valves. Hot water under pressure can cause burns.

Steps:

  • Check pressure gauge: Verify system pressure is within the recommended range. Add water via the fill valve if low, following manufacturer instructions.
  • Bleed air: Bleed radiators or air vents to remove trapped air that can stop flow.
  • Test circulator: Ensure the circulator pump runs when there is a call for heat. Replace if seized or noisy.
  • Check low water cutoff: Test and, if necessary, replace the low water cutoff device.

Hydronic safety faults should be handled by a qualified heating technician.

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Repair Difficulty

Professional Required 5/5

Required Part

Low Water Cutoff
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