Sanding large areas

[paulmagno]

I have to repaint 6 garage doors I painted some years ago with Weathershield. I would like to use a power Sander as don't fancy hand sanding this large area.
Ideas as to the best power sander. The build is tongue and groove verticals

 

[MrTinker]

I'm guessing you don't want to take it back to bare timber, just sand down to re-coat, if so I would use a 6" random orbital sander, by far the best for this type of work.
The sanding disks for these are very expensive from diy sheds, I get mine from a car bodyshop/paint supplier, much cheeper, also i'd use a 80 grit to take the rough stuff off, and finish with a 120 grit.