I'm about to start building a new home. Right now I don't know if I will be installing AC or not. If I do, it will be a mini split unit in a couple of the rooms.

I'd like to avoid having the tubing etc. running up the outside and through the walls, instead, in case I do install the AC later, I'd like to design the house with conduit pre-installed in the walls from where the wall units will be located down to where the compressor will be.

I can't find any information on what size conduit I should install to accommodate the wiring, ducting etc for the run from the wall unit to the compressor.

Any ideas?