What size AC for Pampa, TX? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 37,300 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 644 square feet in this climate. For a single room, size by the room: 18.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Pampa #2 (0.7 mi away). Jul is the hottest month, averaging a high of 92.8°F and a low of 66.9°F, with about 72 days a year at 90°F or more. That gives a design temperature of 99°F against 75°F inside.

What it costs to run

About 2,224 kWh a year at SEER2 14.3, or roughly $356 at Texas's average residential rate of 16.03¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Pampa

Of the 37,300 BTU/hr, 17,280 comes through walls, roof and windows on a 99°F afternoon (46%), 13,000 is sun on the house (35%), 2,120 is four people and their appliances, and 4,900 is moisture the coil has to wring out of Pampa's summer air (13%).

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 32,400 BTU/hr before the moisture allowance.

Other house sizes in Pampa

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 6,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,200 BTU/hr.

Month by month in Pampa

Jul alone uses 29% of the year's cooling energy. The unit runs the equivalent of 853 hours a year at full output.

Pampa against nearby cities

Of 252 Texas cities here, Pampa has the 248th highest cooling load. The range runs from Levelland at 37,300 BTU/hr to Laredo at 51,500.

Where Pampa's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Pampa #2, 0.7 miles from the center of Pampa at 3,150 ft above sea level. That is close enough that the station's summers are Pampa's summers.

No other city in this set uses Pampa #2, so this sizing is Pampa's alone.

The sun over Pampa in late July

At 35.55°N, the noon sun on 21 July stands 74.9° above the horizon over Pampa and the day runs 14 h 03 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.

16,487 people live in Pampa, the 181st largest of the 252 Texas cities sized on this site. Coordinates used: 35.5479, -100.9650.

Pampa AC sizing questions