What size AC for North Myrtle Beach, SC? 3 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in North Myrtle Beach needs

3 tons central AC or heat pump, about 35,600 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 18% 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 675 square feet in this climate. For a single room, size by the room: 17.8 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at N Myrtle Beach (0.9 mi away). Jul is the hottest month, averaging a high of 87.6°F and a low of 73.7°F, with about 21 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 3,147 kWh a year at SEER2 14.3, or roughly $500 at South Carolina's average residential rate of 15.9¢ per kWh. Cooling runs 6 months of the year here.

What drives the load in North Myrtle Beach

Of the 35,600 BTU/hr, 12,240 comes through walls, roof and windows on a 92°F afternoon (34%), 13,000 is sun on the house (37%), 2,120 is four people and their appliances, and 8,200 is moisture the coil has to wring out of North Myrtle Beach's summer air (23%).

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 North Myrtle Beach

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,700 BTU/hr; a 350 sq ft living room needs about 6,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,700 BTU/hr.

Month by month in North Myrtle Beach

Jul alone uses 24% of the year's cooling energy. The unit runs the equivalent of 1,265 hours a year at full output.

North Myrtle Beach against nearby cities

Of 42 South Carolina cities here, North Myrtle Beach has the 39th highest cooling load. The range runs from Gaffney at 32,300 BTU/hr to Columbia at 43,100.

Where North Myrtle Beach's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is N Myrtle Beach, 0.9 miles from the center of North Myrtle Beach at 29 ft above sea level. That is close enough that the station's summers are North Myrtle Beach's summers.

1 other city uses the same station and get the same climate inputs. The closest to North Myrtle Beach: Myrtle Beach (13 mi away, 12 mi from the station). North Myrtle Beach sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over North Myrtle Beach in late July

At 33.82°N, the noon sun on 21 July stands 76.6° above the horizon over North Myrtle Beach and the day runs 13 h 55 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.

20,798 people live in North Myrtle Beach, the 27th largest of the 42 South Carolina cities sized on this site. Coordinates used: 33.8245, -78.7087.

North Myrtle Beach AC sizing questions