Drazice combined heater shows F4; priority switching between electric and coil heating does not work correctly.

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

Incorrect configuration of priority mode, firmware glitch, defective control board, stuck relay contacts

Safety: Disconnect power before accessing the control panel.

Steps:

Consult the Drazice manual to enter the installer or advanced settings menu.
Verify that the priority mode (electric vs. coil) is set according to your installation requirements.
Restore factory settings for control parameters if the manual allows.
Power-cycle the unit by switching OFF/ON at the breaker.
If F4 persists and the heater does not switch modes correctly, the control board may have a hardware fault and should be replaced by an authorized technician.

Professional Required 5/5

Main Control PCB

Check Price on Amazon

We may earn a commission from links on this page.