What size AC for South River, NJ? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 30,600 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 37% 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 783 square feet in this climate. For a single room, size by the room: 15.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at New Brunswick 3 Se (3 mi away). Jul is the hottest month, averaging a high of 86.5°F and a low of 65.6°F, with about 24 days a year at 90°F or more. That gives a design temperature of 91°F against 75°F inside.

What it costs to run

About 1,441 kWh a year at SEER2 14.3, or roughly $347 at New Jersey's average residential rate of 24.09¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in South River

Of the 30,600 BTU/hr, 11,520 comes through walls, roof and windows on a 91°F afternoon (38%), 13,000 is sun on the house (42%), 2,120 is four people and their appliances, and 4,000 is moisture the coil has to wring out of South River's summer air (13%).

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 26,640 BTU/hr before the moisture allowance.

Other house sizes in South River

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,300 BTU/hr; a 350 sq ft living room needs about 5,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,200 BTU/hr.

Month by month in South River

Jul alone uses 33% of the year's cooling energy. The unit runs the equivalent of 673 hours a year at full output.

South River against nearby cities

Of 116 New Jersey cities here, South River has the 75th highest cooling load. The range runs from Hackettstown at 26,400 BTU/hr to Camden at 34,300.

Where South River's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is New Brunswick 3 Se, 3 miles from the center of South River at 111 ft above sea level. That is close enough that the station's summers are South River's summers.

No other city in this set uses New Brunswick 3 Se, so this sizing is South River's alone.

The sun over South River in late July

At 40.45°N, the noon sun on 21 July stands 70.0° above the horizon over South River and the day runs 14 h 28 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.

16,392 people live in South River, the 60th largest of the 116 New Jersey cities sized on this site. Coordinates used: 40.4457, -74.3785.

South River AC sizing questions