What size AC for Bethany, OK? 4 tons for 2,000 sq ft

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

4 tons central AC or heat pump, about 44,000 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.7 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 4 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 546 square feet in this climate. For a single room, size by the room: 22 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Oklahoma City Wiley Post Airport (2.4 mi away). Jul is the hottest month, averaging a high of 94.7°F and a low of 73.1°F, with about 76 days a year at 90°F or more. That gives a design temperature of 101°F against 75°F inside.

What it costs to run

About 3,404 kWh a year at SEER2 14.3, or roughly $470 at Oklahoma's average residential rate of 13.81¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Bethany

Of the 44,000 BTU/hr, 18,720 comes through walls, roof and windows on a 101°F afternoon (43%), 13,000 is sun on the house (30%), 2,120 is four people and their appliances, and 10,200 is moisture the coil has to wring out of Bethany's summer air (23%).

Heat through the shell is the biggest share here, so insulation and air sealing cut the size you need more than shading would. Sensible heat totals 33,840 BTU/hr before the moisture allowance.

Other house sizes in Bethany

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,300 BTU/hr; a 350 sq ft living room needs about 7,700 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 13,200 BTU/hr.

Month by month in Bethany

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 1,107 hours a year at full output.

Bethany against nearby cities

Of 45 Oklahoma cities here, Bethany has the 10th highest cooling load. The range runs from Miami at 35,600 BTU/hr to Ardmore at 44,900.

Where Bethany's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Oklahoma City Wiley Post Airport, 2.4 miles from the center of Bethany at 1,280 ft above sea level. That is close enough that the station's summers are Bethany's summers.

2 other cities use the same station and get the same climate inputs. The closest to Bethany: Warr Acres (2 mi away, 1.9 mi from the station), Yukon (7 mi away, 6.9 mi from the station). Bethany is farther from the station than 1 of them.

The sun over Bethany in late July

At 35.51°N, the noon sun on 21 July stands 74.9° above the horizon over Bethany and the day runs 14 h 03 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.

20,421 people live in Bethany, the 26th largest of the 45 Oklahoma cities sized on this site. Coordinates used: 35.5072, -97.6417.

Bethany AC sizing questions