What size AC for Franklin, KY? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 36,000 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 17% 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 666 square feet in this climate. For a single room, size by the room: 18 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Bowling Green Warren County Airport (18.6 mi away). Jul is the hottest month, averaging a high of 89.7°F and a low of 69.7°F, with about 47 days a year at 90°F or more. That gives a design temperature of 95°F against 75°F inside.

What it costs to run

About 2,470 kWh a year at SEER2 14.3, or roughly $351 at Kentucky's average residential rate of 14.2¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Franklin

Of the 36,000 BTU/hr, 14,400 comes through walls, roof and windows on a 95°F afternoon (40%), 13,000 is sun on the house (36%), 2,120 is four people and their appliances, and 6,500 is moisture the coil has to wring out of Franklin's summer air (18%).

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 29,520 BTU/hr before the moisture allowance.

Other house sizes in Franklin

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 6,300 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,800 BTU/hr.

Month by month in Franklin

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 981 hours a year at full output.

Franklin against nearby cities

Of 42 Kentucky cities here, Franklin has the 5th highest cooling load. The range runs from Versailles at 29,000 BTU/hr to Paducah at 36,900.

Where Franklin's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Bowling Green Warren County Airport, 18.6 miles from the center of Franklin at 523 ft above sea level. That is close enough that the station's summers are Franklin's summers.

1 other city uses the same station and get the same climate inputs. The closest to Franklin: Bowling Green (19 mi away, 1 mi from the station). Franklin is farther from the station than 1 of them.

The sun over Franklin in late July

At 36.72°N, the noon sun on 21 July stands 73.7° above the horizon over Franklin and the day runs 14 h 09 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.

10,524 people live in Franklin, the 41st largest of the 42 Kentucky cities sized on this site. Coordinates used: 36.7180, -86.5576.

Franklin AC sizing questions