Boiler displays E20; no heating; cylinder icon may flash on system/heat-only models

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

Failed Dimplex cylinder NTC sensor, Faulty wired cylinder thermostat connected to Dimplex boiler, Loose sensor pocket or poor contact with cylinder

Safety first: Isolate power before accessing cylinder wiring or sensors. Hot water cylinders can be very hot.

User checks:

Cylinder stat setting: Ensure the mechanical cylinder thermostat (if fitted) is set to an appropriate temperature (typically 60°C).
Reset: After adjusting, reset the Dimplex boiler and check if E20 clears.

Professional repair:

Test and replace the Dimplex cylinder NTC sensor or thermostat.
Ensure the sensor is fully inserted into the cylinder pocket with good thermal contact.

Medium 3/5

Dimplex cylinder NTC sensor / thermostat

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