What size AC for Philadelphia, PA? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 34,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 23% 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 701 square feet in this climate. For a single room, size by the room: 17.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Ne Phila Airport (8 mi away). Jul is the hottest month, averaging a high of 88.2°F and a low of 69.4°F, with about 29 days a year at 90°F or more. That gives a design temperature of 93°F against 75°F inside.

What it costs to run

About 2,027 kWh a year at SEER2 14.3, or roughly $428 at Pennsylvania's average residential rate of 21.13¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Philadelphia

Of the 34,300 BTU/hr, 12,960 comes through walls, roof and windows on a 93°F afternoon (38%), 13,000 is sun on the house (38%), 2,120 is four people and their appliances, and 6,200 is moisture the coil has to wring out of Philadelphia's summer air (18%).

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 28,080 BTU/hr before the moisture allowance.

Other house sizes in Philadelphia

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 10,300 BTU/hr.

Month by month in Philadelphia

Jul alone uses 31% of the year's cooling energy. The unit runs the equivalent of 846 hours a year at full output.

Philadelphia against nearby cities

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

Where Philadelphia's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Ne Phila Airport, 8 miles from the center of Philadelphia at 108 ft above sea level. That is close enough that the station's summers are Philadelphia's summers.

1 other city uses the same station and get the same climate inputs. The closest to Philadelphia: Burlington (16 mi away, 8.5 mi from the station). Philadelphia sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Philadelphia in late July

At 40.01°N, the noon sun on 21 July stands 70.4° above the horizon over Philadelphia and the day runs 14 h 26 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.

1,573,916 people live in Philadelphia, the largest of the 68 Pennsylvania cities sized on this site. Coordinates used: 40.0094, -75.1333.

Philadelphia AC sizing questions