Ariston DHW Temperature Sensor Fault

Boiler shows 701, DHW temperature unstable or too hot, CH may be normal

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 DHW NTC sensor, Limescale on DHW heat exchanger affecting readings, Loose sensor connection, PCB sensor input fault

Safety: Isolate power and water before removing covers.

Locate DHW NTC: Find the DHW temperature sensor on the domestic hot water outlet or plate heat exchanger.
Inspect and reseat: Check the sensor is firmly attached and wiring is intact. Reseat the connector.
Resistance test: With power off, measure sensor resistance and compare to Ariston's chart. Replace if out of range.
Descale plate heat exchanger: Heavy limescale can cause temperature spikes. A professional can remove and chemically descale the DHW plate heat exchanger.

Hard 4/5

DHW Temperature Sensor (NTC)

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