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

What size AC a 2,000 sq ft house in Guthrie 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 Guthrie Municipal Airport (1.7 mi away). Jul is the hottest month, averaging a high of 94°F and a low of 72.3°F, with about 83 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 3,287 kWh a year at SEER2 14.3, or roughly $454 at Oklahoma's average residential rate of 13.81¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Guthrie

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 Guthrie'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 Guthrie

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 Guthrie

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 1,069 hours a year at full output.

Guthrie against nearby cities

Of 45 Oklahoma cities here, Guthrie has the 13th highest cooling load. The range runs from Miami at 35,600 BTU/hr to Ardmore at 44,900.

Where Guthrie's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Guthrie Municipal Airport, 1.7 miles from the center of Guthrie at 1,065 ft above sea level. That is close enough that the station's summers are Guthrie's summers.

1 other city uses the same station and get the same climate inputs. The closest to Guthrie: Edmond (14 mi away, 12.3 mi from the station). Guthrie sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Guthrie in late July

At 35.88°N, the noon sun on 21 July stands 74.5° above the horizon over Guthrie and the day runs 14 h 05 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.

11,682 people live in Guthrie, the 41st largest of the 45 Oklahoma cities sized on this site. Coordinates used: 35.8765, -97.4087.

Guthrie AC sizing questions