What size AC for Scottsdale, AZ? 5 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in Scottsdale needs

5 tons central AC or heat pump, about 54,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, which falls short here. On a design day the unit runs flat out and the house still drifts above 75°F by late afternoon.

If a contractor quotes you more than 5 tons for an average 2,000 sq ft house here, ask to see the Manual J load calculation behind it before you sign. That works out to one ton per 442 square feet in this climate. For a single room, size by the room: 27.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Scottsdale Municipal Airport (6.1 mi away). Jul is the hottest month, averaging a high of 104.1°F and a low of 82.6°F, with about 161 days a year at 90°F or more. That gives a design temperature of 112°F against 75°F inside.

What it costs to run

About 6,550 kWh a year at SEER2 14.3, or roughly $1,006 at Arizona's average residential rate of 15.36¢ per kWh. Cooling runs 9 months of the year here.

What drives the load in Scottsdale

Of the 54,300 BTU/hr, 26,640 comes through walls, roof and windows on a 112°F afternoon (49%), 13,000 is sun on the house (24%), 2,120 is four people and their appliances, and 12,500 is moisture the coil has to wring out of Scottsdale's summer air (23%).

Heat through the shell is the biggest share here, so insulation and air sealing cut the size you need more than shading would. Sensible heat totals 41,760 BTU/hr before the moisture allowance.

Other house sizes in Scottsdale

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 4,100 BTU/hr; a 350 sq ft living room needs about 9,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 16,300 BTU/hr.

Month by month in Scottsdale

Jul alone uses 21% of the year's cooling energy. The unit runs the equivalent of 1,725 hours a year at full output.

Scottsdale against nearby cities

Of 44 Arizona cities here, Scottsdale has the 21st highest cooling load. The range runs from Flagstaff at 24,000 BTU/hr to Bullhead City at 60,800.

Where Scottsdale's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Scottsdale Municipal Airport, 6.1 miles from the center of Scottsdale at 1,431 ft above sea level. That is close enough that the station's summers are Scottsdale's summers.

2 other cities use the same station and get the same climate inputs. The closest to Scottsdale: Fountain Hills (9 mi away, 10.6 mi from the station), Paradise Valley (11 mi away, 4.7 mi from the station). Scottsdale is farther from the station than 1 of them.

The sun over Scottsdale in late July

At 33.68°N, the noon sun on 21 July stands 76.7° above the horizon over Scottsdale and the day runs 13 h 55 min from sunrise to sunset. A lower noon sun puts more of the day's heat on east and west walls than on the roof, which is why shading west glass pays off here. Shorter days give the house a longer night to shed the day's heat.

246,170 people live in Scottsdale, the 7th largest of the 44 Arizona cities sized on this site. Coordinates used: 33.6843, -111.8614.

Scottsdale AC sizing questions