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

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

2.5 tons central AC or heat pump, about 29,000 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 45% 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 828 square feet in this climate. For a single room, size by the room: 14.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Piqua Wwtp (1.2 mi away). Jul is the hottest month, averaging a high of 84.3°F and a low of 64.5°F, with about 17 days a year at 90°F or more. That gives a design temperature of 89°F against 75°F inside.

What it costs to run

About 1,324 kWh a year at SEER2 14.3, or roughly $249 at Ohio's average residential rate of 18.81¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Piqua

Of the 29,000 BTU/hr, 10,080 comes through walls, roof and windows on a 89°F afternoon (35%), 13,000 is sun on the house (45%), 2,120 is four people and their appliances, and 3,800 is moisture the coil has to wring out of Piqua'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 25,200 BTU/hr before the moisture allowance.

Other house sizes in Piqua

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,200 BTU/hr; a 350 sq ft living room needs about 5,100 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,700 BTU/hr.

Month by month in Piqua

Jul alone uses 31% of the year's cooling energy. The unit runs the equivalent of 653 hours a year at full output.

Piqua against nearby cities

Of 176 Ohio cities here, Piqua has the 76th highest cooling load. The range runs from Conneaut at 24,100 BTU/hr to Hamilton at 31,500.

Where Piqua's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Piqua Wwtp, 1.2 miles from the center of Piqua at 853 ft above sea level. That is close enough that the station's summers are Piqua's summers.

No other city in this set uses Piqua Wwtp, so this sizing is Piqua's alone.

The sun over Piqua in late July

At 40.15°N, the noon sun on 21 July stands 70.3° above the horizon over Piqua and the day runs 14 h 26 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.

20,940 people live in Piqua, the 81st largest of the 176 Ohio cities sized on this site. Coordinates used: 40.1471, -84.2435.

Piqua AC sizing questions