What size AC for Alexander City, AL? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 37,800 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.1 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 3.5 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 635 square feet in this climate. For a single room, size by the room: 18.9 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Alexander City (1.5 mi away). Jul is the hottest month, averaging a high of 91.2°F and a low of 69.7°F, with about 62 days a year at 90°F or more. That gives a design temperature of 97°F against 75°F inside.

What it costs to run

About 2,805 kWh a year at SEER2 14.3, or roughly $463 at Alabama's average residential rate of 16.51¢ per kWh. Cooling runs 6 months of the year here.

What drives the load in Alexander City

Of the 37,800 BTU/hr, 15,840 comes through walls, roof and windows on a 97°F afternoon (42%), 13,000 is sun on the house (34%), 2,120 is four people and their appliances, and 6,800 is moisture the coil has to wring out of Alexander City's summer air (18%).

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 30,960 BTU/hr before the moisture allowance.

Other house sizes in Alexander City

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,800 BTU/hr; a 350 sq ft living room needs about 6,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,300 BTU/hr.

Month by month in Alexander City

Jul alone uses 25% of the year's cooling energy. The unit runs the equivalent of 1,062 hours a year at full output.

Alexander City against nearby cities

Of 66 Alabama cities here, Alexander City has the 39th highest cooling load. The range runs from Boaz at 30,600 BTU/hr to Montgomery at 44,000.

Where Alexander City's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Alexander City, 1.5 miles from the center of Alexander City at 660 ft above sea level. That is close enough that the station's summers are Alexander City's summers.

No other city in this set uses Alexander City, so this sizing is Alexander City's alone.

The sun over Alexander City in late July

At 32.92°N, the noon sun on 21 July stands 77.5° above the horizon over Alexander City 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.

14,439 people live in Alexander City, the 52nd largest of the 66 Alabama cities sized on this site. Coordinates used: 32.9167, -85.9406.

Alexander City AC sizing questions