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

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

5 tons central AC or heat pump, about 57,100 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 420 square feet in this climate. For a single room, size by the room: 28.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Casa Grande (3.1 mi away). Jul is the hottest month, averaging a high of 106.8°F and a low of 78.1°F, with about 184 days a year at 90°F or more. That gives a design temperature of 115°F against 75°F inside.

What it costs to run

About 6,225 kWh a year at SEER2 14.3, or roughly $956 at Arizona's average residential rate of 15.36¢ per kWh. Cooling runs 8 months of the year here.

What drives the load in Casa Grande

Of the 57,100 BTU/hr, 28,800 comes through walls, roof and windows on a 115°F afternoon (50%), 13,000 is sun on the house (23%), 2,120 is four people and their appliances, and 13,200 is moisture the coil has to wring out of Casa Grande'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 43,920 BTU/hr before the moisture allowance.

Other house sizes in Casa Grande

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 4,300 BTU/hr; a 350 sq ft living room needs about 10,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 17,100 BTU/hr.

Month by month in Casa Grande

Jul alone uses 21% of the year's cooling energy. The unit runs the equivalent of 1,559 hours a year at full output.

Casa Grande against nearby cities

Of 44 Arizona cities here, Casa Grande has the 13th highest cooling load. The range runs from Flagstaff at 24,000 BTU/hr to Bullhead City at 60,800.

Where Casa Grande's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Casa Grande, 3.1 miles from the center of Casa Grande at 1,400 ft above sea level. That is close enough that the station's summers are Casa Grande's summers.

No other city in this set uses Casa Grande, so this sizing is Casa Grande's alone.

The sun over Casa Grande in late July

At 32.91°N, the noon sun on 21 July stands 77.5° above the horizon over Casa Grande and the day runs 13 h 51 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.

68,927 people live in Casa Grande, the 18th largest of the 44 Arizona cities sized on this site. Coordinates used: 32.9068, -111.7634.

Casa Grande AC sizing questions