What size AC for New Castle, PA? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 28,800 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 46% 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 834 square feet in this climate. For a single room, size by the room: 14.4 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at New Castle 1 N (1.7 mi away). Jul is the hottest month, averaging a high of 85.9°F and a low of 60.4°F, with about 21 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 1,019 kWh a year at SEER2 14.3, or roughly $215 at Pennsylvania's average residential rate of 21.13¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in New Castle

Of the 28,800 BTU/hr, 11,520 comes through walls, roof and windows on a 91°F afternoon (40%), 13,000 is sun on the house (45%), 2,120 is four people and their appliances, and 2,100 is moisture the coil has to wring out of New Castle's summer air (7%).

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 New Castle

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,200 BTU/hr; a 350 sq ft living room needs about 5,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,600 BTU/hr.

Month by month in New Castle

Jul alone uses 33% of the year's cooling energy. The unit runs the equivalent of 506 hours a year at full output.

New Castle against nearby cities

Of 68 Pennsylvania cities here, New Castle has the 25th highest cooling load. The range runs from St. Marys at 21,700 BTU/hr to Philadelphia at 34,300.

Where New Castle's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is New Castle 1 N, 1.7 miles from the center of New Castle at 825 ft above sea level. That is close enough that the station's summers are New Castle's summers.

No other city in this set uses New Castle 1 N, so this sizing is New Castle's alone.

The sun over New Castle in late July

At 41.00°N, the noon sun on 21 July stands 69.4° above the horizon over New Castle and the day runs 14 h 31 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

21,332 people live in New Castle, the 27th largest of the 68 Pennsylvania cities sized on this site. Coordinates used: 40.9956, -80.3458.

New Castle AC sizing questions