What size AC for Cincinnati, OH? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 30,600 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 37% 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 2.5 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 783 square feet in this climate. For a single room, size by the room: 15.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Cincinnati Municipal Airport Lunken Field (5.4 mi away). Jul is the hottest month, averaging a high of 86.6°F and a low of 65.3°F, with about 27 days a year at 90°F or more. That gives a design temperature of 91°F against 75°F inside.

What it costs to run

About 1,564 kWh a year at SEER2 14.3, or roughly $294 at Ohio's average residential rate of 18.81¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Cincinnati

Of the 30,600 BTU/hr, 11,520 comes through walls, roof and windows on a 91°F afternoon (38%), 13,000 is sun on the house (42%), 2,120 is four people and their appliances, and 4,000 is moisture the coil has to wring out of Cincinnati'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 26,640 BTU/hr before the moisture allowance.

Other house sizes in Cincinnati

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,300 BTU/hr; a 350 sq ft living room needs about 5,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,200 BTU/hr.

Month by month in Cincinnati

Jul alone uses 30% of the year's cooling energy. The unit runs the equivalent of 730 hours a year at full output.

Cincinnati against nearby cities

Of 176 Ohio cities here, Cincinnati has the 11th highest cooling load. The range runs from Conneaut at 24,100 BTU/hr to Hamilton at 31,500.

Where Cincinnati's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Cincinnati Municipal Airport Lunken Field, 5.4 miles from the center of Cincinnati at 475 ft above sea level. That is close enough that the station's summers are Cincinnati's summers.

9 other cities use the same station and get the same climate inputs. The closest to Cincinnati: Norwood (3 mi away, 4.3 mi from the station), Newport (4 mi away, 4 mi from the station), Fort Thomas (5 mi away, 2.7 mi from the station), Reading (7 mi away, 8.2 mi from the station), Covington (7 mi away, 7.4 mi from the station). Cincinnati is farther from the station than 3 of them.

The sun over Cincinnati in late July

At 39.14°N, the noon sun on 21 July stands 71.3° above the horizon over Cincinnati and the day runs 14 h 21 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.

314,915 people live in Cincinnati, the 3rd largest of the 176 Ohio cities sized on this site. Coordinates used: 39.1402, -84.5058.

Cincinnati AC sizing questions