Our 5er is set up for a 2nd AC unit up front including a 50 amp service and dedicated 20 circuit with 12 ga wire in the ceiling near the front ceiling vent. I'm thinking about installing the 2nd unit ...
We had a second unit 13.5K unit installed by the dealer. Plus a Fantastik in the bathroom which is on the top level. This is set to blow the rising warm air out of the unit. For a little overkill we have a desk top fan sitting by the bedroom door blowing cool air back down the stairs. So for much of the time we only have one unit on... but for max cooling we turn both on. All is good for us. GPG