What size AC for Swansea, IL? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 34,800 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 21% 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 690 square feet in this climate. For a single room, size by the room: 17.4 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Belleville Siu Research (7.9 mi away). Jul is the hottest month, averaging a high of 90.2°F and a low of 67.8°F, with about 53 days a year at 90°F or more. That gives a design temperature of 96°F against 75°F inside.

What it costs to run

About 2,194 kWh a year at SEER2 14.3, or roughly $422 at Illinois's average residential rate of 19.23¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Swansea

Of the 34,800 BTU/hr, 15,120 comes through walls, roof and windows on a 96°F afternoon (43%), 13,000 is sun on the house (37%), 2,120 is four people and their appliances, and 4,500 is moisture the coil has to wring out of Swansea's summer air (13%).

Heat through the shell is the biggest share here, so insulation and air sealing cut the size you need more than shading would. Sensible heat totals 30,240 BTU/hr before the moisture allowance.

Other house sizes in Swansea

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,600 BTU/hr; a 350 sq ft living room needs about 6,100 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,400 BTU/hr.

Month by month in Swansea

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 902 hours a year at full output.

Swansea against nearby cities

Of 225 Illinois cities here, Swansea has the 16th highest cooling load. The range runs from Fox Lake at 24,900 BTU/hr to Granite City at 36,000.

Where Swansea's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Belleville Siu Research, 7.9 miles from the center of Swansea at 450 ft above sea level. That is close enough that the station's summers are Swansea's summers.

5 other cities use the same station and get the same climate inputs. The closest to Swansea: Belleville (2 mi away, 7.7 mi from the station), Shiloh (4 mi away, 4.3 mi from the station), O'Fallon (5 mi away, 6.7 mi from the station), Troy (13 mi away, 14.5 mi from the station), Highland (22 mi away, 19.3 mi from the station). Swansea is farther from the station than 3 of them.

The sun over Swansea in late July

At 38.55°N, the noon sun on 21 July stands 71.8° above the horizon over Swansea and the day runs 14 h 18 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.

14,445 people live in Swansea, the 171st largest of the 225 Illinois cities sized on this site. Coordinates used: 38.5518, -89.9875.

Swansea AC sizing questions