What size AC for Yankton, SD? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 29,500 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 42% more than this climate needs. An oversized unit cools the air fast, shuts off before it pulls moisture out, and leaves the house cold and clammy.

If a contractor quotes you more than 2.5 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 812 square feet in this climate. For a single room, size by the room: 14.8 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Yankton 2 E (1.7 mi away). Jul is the hottest month, averaging a high of 87.1°F and a low of 63.8°F, with about 33 days a year at 90°F or more. That gives a design temperature of 92°F against 75°F inside.

What it costs to run

About 1,256 kWh a year at SEER2 14.3, or roughly $183 at South Dakota's average residential rate of 14.58¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Yankton

Of the 29,500 BTU/hr, 12,240 comes through walls, roof and windows on a 92°F afternoon (41%), 13,000 is sun on the house (44%), 2,120 is four people and their appliances, and 2,200 is moisture the coil has to wring out of Yankton's summer air (7%).

Sun is the biggest share here, more than heat through the walls, so shading west windows and a light roof cut the size you need more than extra insulation would. Sensible heat totals 27,360 BTU/hr before the moisture allowance.

Other house sizes in Yankton

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,200 BTU/hr; a 350 sq ft living room needs about 5,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,900 BTU/hr.

Month by month in Yankton

Jul alone uses 34% of the year's cooling energy. The unit runs the equivalent of 608 hours a year at full output.

Yankton against nearby cities

Of 14 South Dakota cities here, Yankton has the 2nd highest cooling load. The range runs from Watertown at 24,900 BTU/hr to Pierre at 31,100.

Where Yankton's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Yankton 2 E, 1.7 miles from the center of Yankton at 1,172 ft above sea level. That is close enough that the station's summers are Yankton's summers.

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

The sun over Yankton in late July

At 42.89°N, the noon sun on 21 July stands 67.5° above the horizon over Yankton and the day runs 14 h 42 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

15,670 people live in Yankton, the 6th largest of the 14 South Dakota cities sized on this site. Coordinates used: 42.8898, -97.3927.

Yankton AC sizing questions