What size AC for Pittsfield, MA? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 22,600 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 86% 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 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 1,064 square feet in this climate. For a single room, size by the room: 11.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Pittsfield Municipal Airport (2.3 mi away). Jul is the hottest month, averaging a high of 79.3°F and a low of 58°F, with about 3 days a year at 90°F or more. That gives a design temperature of 83°F against 75°F inside.

What it costs to run

About 449 kWh a year at SEER2 14.3, or roughly $136 at Massachusetts's average residential rate of 30.19¢ per kWh. Cooling runs 3 months of the year here.

What drives the load in Pittsfield

Of the 22,600 BTU/hr, 5,760 comes through walls, roof and windows on a 83°F afternoon (25%), 13,000 is sun on the house (58%), 2,120 is four people and their appliances, and 1,700 is moisture the coil has to wring out of Pittsfield'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 20,880 BTU/hr before the moisture allowance.

Other house sizes in Pittsfield

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,700 BTU/hr; a 350 sq ft living room needs about 4,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 6,800 BTU/hr.

Month by month in Pittsfield

Jul alone uses 39% of the year's cooling energy. The unit runs the equivalent of 285 hours a year at full output.

Pittsfield against nearby cities

Of 58 Massachusetts cities here, Pittsfield has the lowest cooling load. The range runs from Pittsfield at 22,600 BTU/hr to Framingham at 28,000.

Where Pittsfield's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Pittsfield Municipal Airport, 2.3 miles from the center of Pittsfield at 1,152 ft above sea level. That is close enough that the station's summers are Pittsfield's summers.

No other city in this set uses Pittsfield Municipal Airport, so this sizing is Pittsfield's alone.

The sun over Pittsfield in late July

At 42.45°N, the noon sun on 21 July stands 67.9° above the horizon over Pittsfield and the day runs 14 h 39 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.

43,121 people live in Pittsfield, the 32nd largest of the 58 Massachusetts cities sized on this site. Coordinates used: 42.4518, -73.2607.

Pittsfield AC sizing questions