What size AC for San Clemente, CA? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 25,700 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 64% 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 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 935 square feet in this climate. For a single room, size by the room: 12.8 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Camp Pendleton Mcas (17.9 mi away). Aug is the hottest month, averaging a high of 82.7°F and a low of 61.3°F, with about 18 days a year at 90°F or more. That gives a design temperature of 87°F against 75°F inside.

What it costs to run

About 948 kWh a year at SEER2 14.3, or roughly $309 at California's average residential rate of 32.58¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in San Clemente

Of the 25,700 BTU/hr, 8,640 comes through walls, roof and windows on a 87°F afternoon (34%), 13,000 is sun on the house (51%), 2,120 is four people and their appliances, and 1,900 is moisture the coil has to wring out of San Clemente'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 23,760 BTU/hr before the moisture allowance.

Other house sizes in San Clemente

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,900 BTU/hr; a 350 sq ft living room needs about 4,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,700 BTU/hr.

Month by month in San Clemente

Aug alone uses 30% of the year's cooling energy. The unit runs the equivalent of 528 hours a year at full output.

San Clemente against nearby cities

Of 376 California cities here, San Clemente has the 248th highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where San Clemente's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Camp Pendleton Mcas, 17.9 miles from the center of San Clemente at 70 ft above sea level. That is close enough that the station's summers are San Clemente's summers.

No other city in this set uses Camp Pendleton Mcas, so this sizing is San Clemente's alone.

The sun over San Clemente in late July

At 33.45°N, the noon sun on 21 July stands 77.0° above the horizon over San Clemente and the day runs 13 h 54 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.

62,627 people live in San Clemente, the 143rd largest of the 376 California cities sized on this site. Coordinates used: 33.4491, -117.6131.

San Clemente AC sizing questions