What size AC for Durant, OK? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 42,200 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.5 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 569 square feet in this climate. For a single room, size by the room: 21.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Durant (1.4 mi away). Aug is the hottest month, averaging a high of 95.2°F and a low of 70.3°F, with about 82 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 3,217 kWh a year at SEER2 14.3, or roughly $444 at Oklahoma's average residential rate of 13.81¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Durant

Of the 42,200 BTU/hr, 19,440 comes through walls, roof and windows on a 102°F afternoon (46%), 13,000 is sun on the house (31%), 2,120 is four people and their appliances, and 7,600 is moisture the coil has to wring out of Durant'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 34,560 BTU/hr before the moisture allowance.

Other house sizes in Durant

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,200 BTU/hr; a 350 sq ft living room needs about 7,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,700 BTU/hr.

Month by month in Durant

Aug alone uses 25% of the year's cooling energy. The unit runs the equivalent of 1,091 hours a year at full output.

Durant against nearby cities

Of 45 Oklahoma cities here, Durant has the 20th highest cooling load. The range runs from Miami at 35,600 BTU/hr to Ardmore at 44,900.

Where Durant's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Durant, 1.4 miles from the center of Durant at 600 ft above sea level. That is close enough that the station's summers are Durant's summers.

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

The sun over Durant in late July

At 34.00°N, the noon sun on 21 July stands 76.4° above the horizon over Durant and the day runs 13 h 56 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.

20,908 people live in Durant, the 24th largest of the 45 Oklahoma cities sized on this site. Coordinates used: 33.9952, -96.3925.

Durant AC sizing questions