Dash - Funny how you don’t pay attention to these things until it’s too late. From what I recall the unit ran quite a bit and struggled to keep up late in the day when the thermal loads are peaking. Recall that a couple of the estimators believed the return was significantly undersized so I don’t know what effect this would have had. I do remember that the estimator said the load calc indicator the need for slightly over 3.5 tons. I believe he said he went up to the 4 tons because of large cathedral area (20 ft ceilings) and the fact that the Carrier Infinity 16 and the Lennox XP-19 didn’t come in half ton sizes.
The other units (I have in total, ugh!) are 2 tons each. I’m not the original owner but the house is a ranch style built in 1979 and originally had ~ 2400 sq ft. The great room with cathedral ceilings split the house in two and I’m assuming since it was hard to run duct work through the great room that they put in 2 systems. The 3.5 ton cools the kitchen area and great room (~ 1260 sq ft) and a 2 ton cools 3 bedrooms, 2 baths and hall (~ 1140 sq ft). An 800 sq ft master suite and bath was added in the early 90’s. It’s serviced by another separate 2 ton unit. End result I have 3 units (total 7.5 tons) to cool 3200 sq ft.