Can the power of Gialix be reduced ?

Refer to your GIALIX manual.

• Power adjustment can be done either by wiring inside the boiler, by setting in the control system, or by wiring + setting. Instructions for this operation are specific to each model of GIALIX and should be carried out by a qualified professional.

By setting: use parameter 22 (refer to the manual).

Attention!
In order to supply the boiler with a reduced section cable and protect it with a lower-rated circuit breaker, reducing power by setting alone is insufficient: it is imperative to disconnect part of the heating elements (see technical manual).