What size AC for Boaz, AL? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 30,600 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 37% 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 783 square feet in this climate. For a single room, size by the room: 15.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Gadsden 19 N (12.5 mi away). Jul is the hottest month, averaging a high of 86.5°F and a low of 66.7°F, with about 26 days a year at 90°F or more. That gives a design temperature of 91°F against 75°F inside.

What it costs to run

About 1,793 kWh a year at SEER2 14.3, or roughly $296 at Alabama's average residential rate of 16.51¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Boaz

Of the 30,600 BTU/hr, 11,520 comes through walls, roof and windows on a 91°F afternoon (38%), 13,000 is sun on the house (42%), 2,120 is four people and their appliances, and 4,000 is moisture the coil has to wring out of Boaz's summer air (13%).

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 26,640 BTU/hr before the moisture allowance.

Other house sizes in Boaz

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,300 BTU/hr; a 350 sq ft living room needs about 5,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,200 BTU/hr.

Month by month in Boaz

Jul alone uses 28% of the year's cooling energy. The unit runs the equivalent of 837 hours a year at full output.

Boaz against nearby cities

Of 66 Alabama cities here, Boaz has the lowest cooling load. The range runs from Boaz at 30,600 BTU/hr to Montgomery at 44,000.

Where Boaz's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Gadsden 19 N, 12.5 miles from the center of Boaz at 1,152 ft above sea level. That is close enough that the station's summers are Boaz's summers.

1 other city uses the same station and get the same climate inputs. The closest to Boaz: Albertville (5 mi away, 14.3 mi from the station). Boaz sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Boaz in late July

At 34.20°N, the noon sun on 21 July stands 76.2° above the horizon over Boaz 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.

10,473 people live in Boaz, the 63rd largest of the 66 Alabama cities sized on this site. Coordinates used: 34.1990, -86.1552.

Boaz AC sizing questions