(Note that the appearance of the IP box varies, but the function described is the same)
Digital thermostat settings and thermostat errors can cause the heater to not function. Below is a description of the function and possible causes of disturbances and how thermostat errors can be temporarily resolved.
According to the instructions, the knob on the mechanical thermostat must always be set to the maximum position if a digital thermostat is used. The function can be checked by turning the thermostat knob between minimum and maximum. If a faint click is then heard, the thermostat is OK. If no click is heard, the thermostat may be out of order and needs to be replaced. BUT, if there is also a digital thermostat, the heater's own thermostat is not needed and it can be bypassed.
Explanation of connections for digital thermostat
Connect power directly to heater.