What size AC for Vincennes, IN? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 32,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 30% 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 743 square feet in this climate. For a single room, size by the room: 16.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Lawrenceville Vincennes International A (7.5 mi away). Jul is the hottest month, averaging a high of 87.6°F and a low of 67.2°F, with about 41 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 1,917 kWh a year at SEER2 14.3, or roughly $327 at Indiana's average residential rate of 17.04¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Vincennes

Of the 32,300 BTU/hr, 12,960 comes through walls, roof and windows on a 93°F afternoon (40%), 13,000 is sun on the house (40%), 2,120 is four people and their appliances, and 4,200 is moisture the coil has to wring out of Vincennes's summer air (13%).

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 Vincennes

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,400 BTU/hr; a 350 sq ft living room needs about 5,600 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,700 BTU/hr.

Month by month in Vincennes

Jul alone uses 28% of the year's cooling energy. The unit runs the equivalent of 849 hours a year at full output.

Vincennes against nearby cities

Of 88 Indiana cities here, Vincennes has the 7th highest cooling load. The range runs from Auburn at 24,100 BTU/hr to Jasper at 36,400.

Where Vincennes's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Lawrenceville Vincennes International A, across the line in Illinois, 7.5 miles from the center of Vincennes at 427 ft above sea level. That is close enough that the station's summers are Vincennes's summers.

No other city in this set uses Lawrenceville Vincennes International A, so this sizing is Vincennes's alone.

The sun over Vincennes in late July

At 38.68°N, the noon sun on 21 July stands 71.7° above the horizon over Vincennes and the day runs 14 h 19 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.

16,506 people live in Vincennes, the 55th largest of the 88 Indiana cities sized on this site. Coordinates used: 38.6766, -87.5100.

Vincennes AC sizing questions