What size AC for Lewisburg, TN? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 35,600 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 18% 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 674 square feet in this climate. For a single room, size by the room: 17.8 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Lewisburg Experiment Station (2.8 mi away). Jul is the hottest month, averaging a high of 91°F and a low of 66.6°F, with about 58 days a year at 90°F or more. That gives a design temperature of 97°F against 75°F inside.

What it costs to run

About 2,179 kWh a year at SEER2 14.3, or roughly $301 at Tennessee's average residential rate of 13.8¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Lewisburg

Of the 35,600 BTU/hr, 15,840 comes through walls, roof and windows on a 97°F afternoon (44%), 13,000 is sun on the house (37%), 2,120 is four people and their appliances, and 4,600 is moisture the coil has to wring out of Lewisburg'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 30,960 BTU/hr before the moisture allowance.

Other house sizes in Lewisburg

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,700 BTU/hr; a 350 sq ft living room needs about 6,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,700 BTU/hr.

Month by month in Lewisburg

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 875 hours a year at full output.

Lewisburg against nearby cities

Of 65 Tennessee cities here, Lewisburg has the 33rd highest cooling load. The range runs from Crossville at 27,300 BTU/hr to Memphis at 41,200.

Where Lewisburg's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Lewisburg Experiment Station, 2.8 miles from the center of Lewisburg at 787 ft above sea level. That is close enough that the station's summers are Lewisburg's summers.

No other city in this set uses Lewisburg Experiment Station, so this sizing is Lewisburg's alone.

The sun over Lewisburg in late July

At 35.45°N, the noon sun on 21 July stands 74.9° above the horizon over Lewisburg and the day runs 14 h 03 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.

13,473 people live in Lewisburg, the 49th largest of the 65 Tennessee cities sized on this site. Coordinates used: 35.4516, -86.7907.

Lewisburg AC sizing questions