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

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

4 tons central AC or heat pump, about 44,900 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.7 tons. This is one of the climates the chart was written for.

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 534 square feet in this climate. For a single room, size by the room: 22.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Athens (2.7 mi away). Aug is the hottest month, averaging a high of 95.1°F and a low of 72.3°F, with about 92 days a year at 90°F or more. That gives a design temperature of 102°F against 75°F inside.

What it costs to run

About 3,972 kWh a year at SEER2 14.3, or roughly $637 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Athens

Of the 44,900 BTU/hr, 19,440 comes through walls, roof and windows on a 102°F afternoon (43%), 13,000 is sun on the house (29%), 2,120 is four people and their appliances, and 10,400 is moisture the coil has to wring out of Athens'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 34,560 BTU/hr before the moisture allowance.

Other house sizes in Athens

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,400 BTU/hr; a 350 sq ft living room needs about 7,900 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 13,500 BTU/hr.

Month by month in Athens

Aug alone uses 23% of the year's cooling energy. The unit runs the equivalent of 1,264 hours a year at full output.

Athens against nearby cities

Of 252 Texas cities here, Athens has the 171st highest cooling load. The range runs from Levelland at 37,300 BTU/hr to Laredo at 51,500.

Where Athens's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Athens, 2.7 miles from the center of Athens at 448 ft above sea level. That is close enough that the station's summers are Athens's summers.

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

The sun over Athens in late July

At 32.20°N, the noon sun on 21 July stands 78.2° above the horizon over Athens and the day runs 13 h 48 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.

13,575 people live in Athens, the 207th largest of the 252 Texas cities sized on this site. Coordinates used: 32.2026, -95.8308.

Athens AC sizing questions