What size AC for Clinton, IA? 2.5 tons for 2,000 sq ft

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

2.5 tons central AC or heat pump, about 28,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 49% 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 853 square feet in this climate. For a single room, size by the room: 14.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Clinton #1 (3.5 mi away). Jul is the hottest month, averaging a high of 83.9°F and a low of 64.8°F, with about 15 days a year at 90°F or more. That gives a design temperature of 88°F against 75°F inside.

What it costs to run

About 1,276 kWh a year at SEER2 14.3, or roughly $186 at Iowa's average residential rate of 14.55¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Clinton

Of the 28,200 BTU/hr, 9,360 comes through walls, roof and windows on a 88°F afternoon (33%), 13,000 is sun on the house (46%), 2,120 is four people and their appliances, and 3,700 is moisture the coil has to wring out of Clinton'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 24,480 BTU/hr before the moisture allowance.

Other house sizes in Clinton

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,100 BTU/hr; a 350 sq ft living room needs about 4,900 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,500 BTU/hr.

Month by month in Clinton

Jul alone uses 32% of the year's cooling energy. The unit runs the equivalent of 648 hours a year at full output.

Clinton against nearby cities

Of 41 Iowa cities here, Clinton has the 23rd highest cooling load. The range runs from Dubuque at 24,900 BTU/hr to Council Bluffs at 34,300.

Where Clinton's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Clinton #1, 3.5 miles from the center of Clinton at 585 ft above sea level. That is close enough that the station's summers are Clinton's summers.

No other city in this set uses Clinton #1, so this sizing is Clinton's alone.

The sun over Clinton in late July

At 41.84°N, the noon sun on 21 July stands 68.6° above the horizon over Clinton and the day runs 14 h 36 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

24,118 people live in Clinton, the 22nd largest of the 41 Iowa cities sized on this site. Coordinates used: 41.8424, -90.2428.

Clinton AC sizing questions