Boiler displays E17, may be associated with very low return temperatures or cold radiators.

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

Return NTC out of range, Incorrect hydraulic balancing, Undersized system flow, Faulty mixing valve (on system boilers with buffer tank)

Safety: Ensure the system is cool before adjusting valves.

Check radiator valves: Make sure enough radiators are open to allow proper flow. Closing too many can cause low return temperatures and protection faults.
Balance the system: Slightly open lockshield valves on cold radiators to improve return temperature.
Inspect mixing valve (if fitted): On Atlantic system setups with a mixing valve, ensure it is not stuck in a cold position.
Professional service: A technician should verify sensor readings and adjust system hydraulics if necessary.

Medium 3/5

Hydraulic Mixing Valve

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