E20 error, unit may not respond to user inputs or external controls.

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

Damaged communication cable, Faulty remote controller, Incorrect wiring polarity, PCB communication port failure

Safety: Isolate power before working on low-voltage wiring.

Check remote wiring: Inspect the two-core or bus cable between the water heater and Chaffoteaux remote controller. Look for breaks, loose terminals, or reversed polarity.
Test without remote: Disconnect the remote controller and operate the heater using the onboard controls (if available). If E20 clears, the remote may be faulty.
Replace remote: Fit a known-good Chaffoteaux remote controller and test.
PCB check: If communication still fails, the PCB communication interface may be defective.

Medium 3/5

Remote Control / User Interface Module

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