What size AC for South Burlington, VT? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 25,700 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 64% 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 935 square feet in this climate. For a single room, size by the room: 12.8 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Burlington International Airport (2.7 mi away). Jul is the hottest month, averaging a high of 82.4°F and a low of 62.4°F, with about 8 days a year at 90°F or more. That gives a design temperature of 87°F against 75°F inside.

What it costs to run

About 856 kWh a year at SEER2 14.3, or roughly $205 at Vermont's average residential rate of 23.93¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in South Burlington

Of the 25,700 BTU/hr, 8,640 comes through walls, roof and windows on a 87°F afternoon (34%), 13,000 is sun on the house (51%), 2,120 is four people and their appliances, and 1,900 is moisture the coil has to wring out of South Burlington'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 23,760 BTU/hr before the moisture allowance.

Other house sizes in South Burlington

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,900 BTU/hr; a 350 sq ft living room needs about 4,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,700 BTU/hr.

Month by month in South Burlington

Jul alone uses 36% of the year's cooling energy. The unit runs the equivalent of 477 hours a year at full output.

South Burlington against nearby cities

Of 4 Vermont cities here, South Burlington has the 2nd highest cooling load. The range runs from Rutland at 22,500 BTU/hr to Burlington at 25,700.

Where South Burlington's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Burlington International Airport, 2.7 miles from the center of South Burlington at 332 ft above sea level. That is close enough that the station's summers are South Burlington's summers.

2 other cities use the same station and get the same climate inputs. The closest to South Burlington: Burlington (5 mi away, 4.7 mi from the station), Essex Junction (5 mi away, 2.3 mi from the station). South Burlington is farther from the station than 1 of them.

The sun over South Burlington in late July

At 44.44°N, the noon sun on 21 July stands 66.0° above the horizon over South Burlington and the day runs 14 h 51 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.

21,713 people live in South Burlington, the 2nd largest of the 4 Vermont cities sized on this site. Coordinates used: 44.4366, -73.1811.

South Burlington AC sizing questions