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

What size AC a 2,000 sq ft house in Frankfort 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 Frankfort Capital City Airport (2.2 mi away). Jul is the hottest month, averaging a high of 87.6°F and a low of 66.8°F, with about 28 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 1,851 kWh a year at SEER2 14.3, or roughly $263 at Kentucky's average residential rate of 14.2¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Frankfort

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 Frankfort'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 Frankfort

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 Frankfort

Jul alone uses 28% of the year's cooling energy. The unit runs the equivalent of 820 hours a year at full output.

Frankfort against nearby cities

Of 42 Kentucky cities here, Frankfort has the 19th highest cooling load. The range runs from Versailles at 29,000 BTU/hr to Paducah at 36,900.

Where Frankfort's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Frankfort Capital City Airport, 2.2 miles from the center of Frankfort at 777 ft above sea level. That is close enough that the station's summers are Frankfort's summers.

No other city in this set uses Frankfort Capital City Airport, so this sizing is Frankfort's alone.

The sun over Frankfort in late July

At 38.20°N, the noon sun on 21 July stands 72.2° above the horizon over Frankfort and the day runs 14 h 16 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.

28,610 people live in Frankfort, the 14th largest of the 42 Kentucky cities sized on this site. Coordinates used: 38.1950, -84.8659.

Frankfort AC sizing questions