What size AC for Show Low, AZ? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 28,000 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 50% more than this climate needs. An oversized unit cools the air fast, shuts off before it pulls moisture out, and leaves the house cold and clammy.

If a contractor quotes you more than 2.5 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 857 square feet in this climate. For a single room, size by the room: 14 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Show Low Airport (1.8 mi away). Jul is the hottest month, averaging a high of 85.3°F and a low of 59.2°F, with about 20 days a year at 90°F or more. That gives a design temperature of 90°F against 75°F inside.

What it costs to run

About 801 kWh a year at SEER2 14.3, or roughly $123 at Arizona's average residential rate of 15.36¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in Show Low

Of the 28,000 BTU/hr, 10,800 comes through walls, roof and windows on a 90°F afternoon (39%), 13,000 is sun on the house (46%), 2,120 is four people and their appliances, and 2,100 is moisture the coil has to wring out of Show Low's summer air (8%).

Sun is the biggest share here, more than heat through the walls, so shading west windows and a light roof cut the size you need more than extra insulation would. Sensible heat totals 25,920 BTU/hr before the moisture allowance.

Other house sizes in Show Low

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,100 BTU/hr; a 350 sq ft living room needs about 4,900 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,400 BTU/hr.

Month by month in Show Low

Jul alone uses 37% of the year's cooling energy. The unit runs the equivalent of 409 hours a year at full output.

Show Low against nearby cities

Of 44 Arizona cities here, Show Low has the 43rd highest cooling load. The range runs from Flagstaff at 24,000 BTU/hr to Bullhead City at 60,800.

Where Show Low's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Show Low Airport, 1.8 miles from the center of Show Low at 6,411 ft above sea level. That is close enough that the station's summers are Show Low's summers.

No other city in this set uses Show Low Airport, so this sizing is Show Low's alone.

The sun over Show Low in late July

At 34.27°N, the noon sun on 21 July stands 76.1° above the horizon over Show Low and the day runs 13 h 57 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.

12,366 people live in Show Low, the 43rd largest of the 44 Arizona cities sized on this site. Coordinates used: 34.2651, -110.0383.

Show Low AC sizing questions