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

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

2.5 tons central AC or heat pump, about 27,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 54% 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 882 square feet in this climate. For a single room, size by the room: 13.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Lancaster Fairfield County Airport (3.8 mi away). Jul is the hottest month, averaging a high of 84.4°F and a low of 62.2°F, with about 16 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 1,076 kWh a year at SEER2 14.3, or roughly $202 at Ohio's average residential rate of 18.81¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Lancaster

Of the 27,200 BTU/hr, 10,080 comes through walls, roof and windows on a 89°F afternoon (37%), 13,000 is sun on the house (48%), 2,120 is four people and their appliances, and 2,000 is moisture the coil has to wring out of Lancaster's summer air (7%).

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 Lancaster

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,000 BTU/hr; a 350 sq ft living room needs about 4,800 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,200 BTU/hr.

Month by month in Lancaster

Jul alone uses 32% of the year's cooling energy. The unit runs the equivalent of 565 hours a year at full output.

Lancaster against nearby cities

Of 176 Ohio cities here, Lancaster has the 108th highest cooling load. The range runs from Conneaut at 24,100 BTU/hr to Hamilton at 31,500.

Where Lancaster's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Lancaster Fairfield County Airport, 3.8 miles from the center of Lancaster at 849 ft above sea level. That is close enough that the station's summers are Lancaster's summers.

No other city in this set uses Lancaster Fairfield County Airport, so this sizing is Lancaster's alone.

The sun over Lancaster in late July

At 39.73°N, the noon sun on 21 July stands 70.7° above the horizon over Lancaster and the day runs 14 h 24 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.

41,671 people live in Lancaster, the 31st largest of the 176 Ohio cities sized on this site. Coordinates used: 39.7252, -82.6052.

Lancaster AC sizing questions