Maxair vent fan

That's reassuring to hear.  We plan to fit one in place of the Remis 400x400mm roof vent in the galley area of our Kemerton, in order to extract damp air when cooking and hopefully reduce fogging up of the windows.  Having looked at several fan options, the Maxxair appears to be the best performing and gets good reviews.

As for getting a 12v feed to it, I have removed the internal assembly of the Remis and exposed the edge of the roof lining.  I'm confident I can thread a cable behind the roof lining and into the nearest cabinet, which in my case contains the microwave, and only about 300mm away from the Maxxair location.  Beneath the microwave is the Dometic hob fan hood which is where I'll find a 12v supply.  I can connect into this and add an in-line fuse to supply the Maxxair.  I'll position the in-line fuse so it can be reached and pulled out on spare cable via the gap underneath the microwave casing.

Your installation details will no doubt be different but if you can thread cable behind the roof lining and into a high-level locker or cabinet then I imagine you should then be able to pick up a suitable 12v supply somewhere.  Whichever circuit you manage to connect into, make sure its fuse is rated to take account of the additional load imposed by the Maxxair and connect an additional fuse just for the latter as mentioned above.

Tim