Hi, its a vent axia 100LT
Thanks. It has the look of an older design, the casing is large, the electric usage and the noise are both greater than modern designs with ball-bearing motors. However, the air throughput (if running well) is good at around 100 cu.m/hr.
Does it sound like it is running well, and is the delay timer set to max?
If yes, and extraction is poor, probably due to the duct, you will need a more powerful one. Can you get at the duct? An inline fan can be around three times as powerful.
If the noise is a nuisance, we can easily find a quieter one
You need fresh air to enter, preferably through the gap under the bathroom door, since water vapour is lighter than air so will rise towards the ceiling.
If it is a steamy bathroom with a shower, you need a more powerful fan. The one you gave is fine for a WC, and adequate for a room with a bath if you run it consistently and long enough. Having the fan automatically start with the light switch defeats people who dislike ventilation.
A cold bathroom, with uninsulated walls, is very prone to condensation, so needs extra ventilation, and preferably improved insulation. Heating a cold room is expensive.