What size AC for Bangor, ME? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 24,100 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 74% 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 996 square feet in this climate. For a single room, size by the room: 12.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Bangor International Airport (2.6 mi away). Jul is the hottest month, averaging a high of 80.4°F and a low of 58.6°F, with about 6 days a year at 90°F or more. That gives a design temperature of 85°F against 75°F inside.

What it costs to run

About 495 kWh a year at SEER2 14.3, or roughly $150 at Maine's average residential rate of 30.23¢ per kWh. Cooling runs 3 months of the year here.

What drives the load in Bangor

Of the 24,100 BTU/hr, 7,200 comes through walls, roof and windows on a 85°F afternoon (30%), 13,000 is sun on the house (54%), 2,120 is four people and their appliances, and 1,800 is moisture the coil has to wring out of Bangor'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 22,320 BTU/hr before the moisture allowance.

Other house sizes in Bangor

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,800 BTU/hr; a 350 sq ft living room needs about 4,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,300 BTU/hr.

Month by month in Bangor

Jul alone uses 41% of the year's cooling energy. The unit runs the equivalent of 294 hours a year at full output.

Bangor against nearby cities

Of 11 Maine cities here, Bangor has the 2nd highest cooling load. The range runs from Waterville at 23,300 BTU/hr to Sanford at 24,900.

Where Bangor's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Bangor International Airport, 2.6 miles from the center of Bangor at 147 ft above sea level. That is close enough that the station's summers are Bangor's summers.

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

The sun over Bangor in late July

At 44.83°N, the noon sun on 21 July stands 65.6° above the horizon over Bangor and the day runs 14 h 54 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.

32,446 people live in Bangor, the 3rd largest of the 11 Maine cities sized on this site. Coordinates used: 44.8296, -68.7888.

Bangor AC sizing questions