What size AC for Abilene, TX? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 46,800 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 4 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 513 square feet in this climate. For a single room, size by the room: 23.4 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Abilene Regional Airport (4.5 mi away). Jul is the hottest month, averaging a high of 96.4°F and a low of 73.1°F, with about 102 days a year at 90°F or more. That gives a design temperature of 104°F against 75°F inside.

What it costs to run

About 4,236 kWh a year at SEER2 14.3, or roughly $679 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Abilene

Of the 46,800 BTU/hr, 20,880 comes through walls, roof and windows on a 104°F afternoon (45%), 13,000 is sun on the house (28%), 2,120 is four people and their appliances, and 10,800 is moisture the coil has to wring out of Abilene'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 36,000 BTU/hr before the moisture allowance.

Other house sizes in Abilene

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,500 BTU/hr; a 350 sq ft living room needs about 8,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 14,000 BTU/hr.

Month by month in Abilene

Jul alone uses 23% of the year's cooling energy. The unit runs the equivalent of 1,294 hours a year at full output.

Abilene against nearby cities

Of 252 Texas cities here, Abilene has the 76th highest cooling load. The range runs from Levelland at 37,300 BTU/hr to Laredo at 51,500.

Where Abilene's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Abilene Regional Airport, 4.5 miles from the center of Abilene at 1,787 ft above sea level. That is close enough that the station's summers are Abilene's summers.

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

The sun over Abilene in late July

At 32.45°N, the noon sun on 21 July stands 77.9° above the horizon over Abilene and the day runs 13 h 49 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.

130,501 people live in Abilene, the 29th largest of the 252 Texas cities sized on this site. Coordinates used: 32.4545, -99.7381.

Abilene AC sizing questions