What size AC for Oroville, CA? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 40,600 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.4 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 3.5 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 592 square feet in this climate. For a single room, size by the room: 20.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Oroville Municipal Airport (3.3 mi away). Jul is the hottest month, averaging a high of 95.8°F and a low of 65.2°F, with about 93 days a year at 90°F or more. That gives a design temperature of 103°F against 75°F inside.

What it costs to run

About 2,428 kWh a year at SEER2 14.3, or roughly $791 at California's average residential rate of 32.58¢ per kWh. Cooling runs 6 months of the year here.

What drives the load in Oroville

Of the 40,600 BTU/hr, 20,160 comes through walls, roof and windows on a 103°F afternoon (50%), 13,000 is sun on the house (32%), 2,120 is four people and their appliances, and 5,300 is moisture the coil has to wring out of Oroville's summer air (13%).

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 35,280 BTU/hr before the moisture allowance.

Other house sizes in Oroville

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,000 BTU/hr; a 350 sq ft living room needs about 7,100 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,200 BTU/hr.

Month by month in Oroville

Jul alone uses 27% of the year's cooling energy. The unit runs the equivalent of 856 hours a year at full output.

Oroville against nearby cities

Of 376 California cities here, Oroville has the 49th highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Oroville's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Oroville Municipal Airport, 3.3 miles from the center of Oroville at 187 ft above sea level. That is close enough that the station's summers are Oroville's summers.

No other city in this set uses Oroville Municipal Airport, so this sizing is Oroville's alone.

The sun over Oroville in late July

At 39.50°N, the noon sun on 21 July stands 70.9° above the horizon over Oroville and the day runs 14 h 23 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.

19,712 people live in Oroville, the 298th largest of the 376 California cities sized on this site. Coordinates used: 39.4952, -121.5599.

Oroville AC sizing questions