What size AC for Harrison, AR? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 33,100 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 27% 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 3 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 725 square feet in this climate. For a single room, size by the room: 16.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Harrison Boone County Airport (2.8 mi away). Jul is the hottest month, averaging a high of 89.1°F and a low of 67.9°F, with about 41 days a year at 90°F or more. That gives a design temperature of 94°F against 75°F inside.

What it costs to run

About 2,049 kWh a year at SEER2 14.3, or roughly $282 at Arkansas's average residential rate of 13.74¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Harrison

Of the 33,100 BTU/hr, 13,680 comes through walls, roof and windows on a 94°F afternoon (41%), 13,000 is sun on the house (39%), 2,120 is four people and their appliances, and 4,300 is moisture the coil has to wring out of Harrison'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 28,800 BTU/hr before the moisture allowance.

Other house sizes in Harrison

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,500 BTU/hr; a 350 sq ft living room needs about 5,800 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,000 BTU/hr.

Month by month in Harrison

Jul alone uses 28% of the year's cooling energy. The unit runs the equivalent of 885 hours a year at full output.

Harrison against nearby cities

Of 39 Arkansas cities here, Harrison has the lowest cooling load. The range runs from Harrison at 33,100 BTU/hr to Fort Smith at 44,000.

Where Harrison's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Harrison Boone County Airport, 2.8 miles from the center of Harrison at 1,371 ft above sea level. That is close enough that the station's summers are Harrison's summers.

No other city in this set uses Harrison Boone County Airport, so this sizing is Harrison's alone.

The sun over Harrison in late July

At 36.24°N, the noon sun on 21 July stands 74.2° above the horizon over Harrison and the day runs 14 h 07 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.

13,723 people live in Harrison, the 28th largest of the 39 Arkansas cities sized on this site. Coordinates used: 36.2426, -93.1176.

Harrison AC sizing questions