I'll start by saying that I know the correct answer is "consult a professional to do a load calculation", but I've consulted two professionals who are coming up with much different answers so I'm feeling stuck.
The house is 2076 square feet, new construction, two-story with most of
the square footage on the ground floor. R-19 insulation in exterior walls and ground floor joints, R-30 in ceiling. One big air return, about 12 registers. 2x4 (I'm pretty sure, a slight chance it's 2x6) frame construction. Furnace in crawl space under house. Have some large windows in great room and a glass slider in dining room but these
all face north, otherwise normal sized windows. Located in Flagstaff, AZ, elevation 6900'. Average high temperature in July (the hottest month): 82 degrees. All-time record high: 97. Humidity: tends to be quite low.... this is the Southwest. This is a town where most people don't have A/C, and the unit won't be heavily used. You can usually get by with your windows open and ceiling fans. It just gets a
little toasty now and then, which is why we want the air.
Once contractor says a 3 ton unit is the way to go, another says 5 ton.
Any opinions regarding who is right?
Tom in PA