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

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

3 tons central AC or heat pump, about 33,900 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 24% 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 707 square feet in this climate. For a single room, size by the room: 17 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Fayetteville Drake Field (5 mi away). Jul is the hottest month, averaging a high of 89.2°F and a low of 66.5°F, with about 41 days a year at 90°F or more. That gives a design temperature of 95°F against 75°F inside.

What it costs to run

About 1,879 kWh a year at SEER2 14.3, or roughly $258 at Arkansas's average residential rate of 13.74¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Farmington

Of the 33,900 BTU/hr, 14,400 comes through walls, roof and windows on a 95°F afternoon (42%), 13,000 is sun on the house (38%), 2,120 is four people and their appliances, and 4,400 is moisture the coil has to wring out of Farmington'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 29,520 BTU/hr before the moisture allowance.

Other house sizes in Farmington

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,600 BTU/hr; a 350 sq ft living room needs about 6,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,200 BTU/hr.

Month by month in Farmington

Jul alone uses 29% of the year's cooling energy. The unit runs the equivalent of 792 hours a year at full output.

Farmington against nearby cities

Of 39 Arkansas cities here, Farmington has the 38th highest cooling load. The range runs from Harrison at 33,100 BTU/hr to Fort Smith at 44,000.

Where Farmington's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Fayetteville Drake Field, 5 miles from the center of Farmington at 1,237 ft above sea level. That is close enough that the station's summers are Farmington's summers.

1 other city uses the same station and get the same climate inputs. The closest to Farmington: Fayetteville (5 mi away, 4.2 mi from the station). Farmington is farther from the station than 1 of them.

The sun over Farmington in late July

At 36.04°N, the noon sun on 21 July stands 74.4° above the horizon over Farmington and the day runs 14 h 06 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.

10,473 people live in Farmington, the 37th largest of the 39 Arkansas cities sized on this site. Coordinates used: 36.0366, -94.2525.

Farmington AC sizing questions