Sorry, thinking about it the XH model may only have two terminals, permanent live and neutral. The pull switch would operate the fan and the humidistat would work independently when it needs to.
You could still use an external pull switch and disable the fans internal pull switch by cutting off the string when it's in the on position but you would lose the automatic humidistat.
If you can live with (and reach) the fans pullswitch then the VA100XH would be ideal as long as you feed it with a permanent live and neutral.
If you require an external pullswitch then it may be better going for a VA100X
You could still use an external pull switch and disable the fans internal pull switch by cutting off the string when it's in the on position but you would lose the automatic humidistat.
If you can live with (and reach) the fans pullswitch then the VA100XH would be ideal as long as you feed it with a permanent live and neutral.
If you require an external pullswitch then it may be better going for a VA100X