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

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

2.5 tons central AC or heat pump, about 26,400 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 59% 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 908 square feet in this climate. For a single room, size by the room: 13.2 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Washington 3 Ne (3.1 mi away). Jul is the hottest month, averaging a high of 83.4°F and a low of 61.7°F, with about 6 days a year at 90°F or more. That gives a design temperature of 88°F against 75°F inside.

What it costs to run

About 995 kWh a year at SEER2 14.3, or roughly $210 at Pennsylvania's average residential rate of 21.13¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Washington

Of the 26,400 BTU/hr, 9,360 comes through walls, roof and windows on a 88°F afternoon (35%), 13,000 is sun on the house (49%), 2,120 is four people and their appliances, and 2,000 is moisture the coil has to wring out of Washington's summer air (8%).

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 24,480 BTU/hr before the moisture allowance.

Other house sizes in Washington

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,000 BTU/hr; a 350 sq ft living room needs about 4,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,900 BTU/hr.

Month by month in Washington

Jul alone uses 31% of the year's cooling energy. The unit runs the equivalent of 538 hours a year at full output.

Washington against nearby cities

Of 68 Pennsylvania cities here, Washington has the 54th highest cooling load. The range runs from St. Marys at 21,700 BTU/hr to Philadelphia at 34,300.

Where Washington's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Washington 3 Ne, 3.1 miles from the center of Washington at 1,300 ft above sea level. That is close enough that the station's summers are Washington's summers.

No other city in this set uses Washington 3 Ne, so this sizing is Washington's alone.

The sun over Washington in late July

At 40.17°N, the noon sun on 21 July stands 70.2° above the horizon over Washington 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.

13,334 people live in Washington, the 47th largest of the 68 Pennsylvania cities sized on this site. Coordinates used: 40.1742, -80.2468.

Washington AC sizing questions