What size AC for Moncks Corner, SC? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 43,100 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.6 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 557 square feet in this climate. For a single room, size by the room: 21.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Moncks Corner 4 N (3 mi away). Jul is the hottest month, averaging a high of 93.1°F and a low of 73.7°F, with about 85 days a year at 90°F or more. That gives a design temperature of 100°F against 75°F inside.

What it costs to run

About 3,885 kWh a year at SEER2 14.3, or roughly $618 at South Carolina's average residential rate of 15.9¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Moncks Corner

Of the 43,100 BTU/hr, 18,000 comes through walls, roof and windows on a 100°F afternoon (42%), 13,000 is sun on the house (30%), 2,120 is four people and their appliances, and 9,900 is moisture the coil has to wring out of Moncks Corner's summer air (23%).

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 33,120 BTU/hr before the moisture allowance.

Other house sizes in Moncks Corner

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 7,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,900 BTU/hr.

Month by month in Moncks Corner

Jul alone uses 23% of the year's cooling energy. The unit runs the equivalent of 1,290 hours a year at full output.

Moncks Corner against nearby cities

Of 42 South Carolina cities here, Moncks Corner has the 3rd highest cooling load. The range runs from Gaffney at 32,300 BTU/hr to Columbia at 43,100.

Where Moncks Corner's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Moncks Corner 4 N, 3 miles from the center of Moncks Corner at 49 ft above sea level. That is close enough that the station's summers are Moncks Corner's summers.

No other city in this set uses Moncks Corner 4 N, so this sizing is Moncks Corner's alone.

The sun over Moncks Corner in late July

At 33.20°N, the noon sun on 21 July stands 77.2° above the horizon over Moncks Corner and the day runs 13 h 53 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.

18,359 people live in Moncks Corner, the 30th largest of the 42 South Carolina cities sized on this site. Coordinates used: 33.1998, -79.9866.

Moncks Corner AC sizing questions