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

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

3.5 tons central AC or heat pump, about 36,500 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 15% 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 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 657 square feet in this climate. For a single room, size by the room: 18.3 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Placerville (2.8 mi away). Jul is the hottest month, averaging a high of 94.1°F and a low of 60.7°F, with about 74 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 1,697 kWh a year at SEER2 14.3, or roughly $553 at California's average residential rate of 32.58¢ per kWh. Cooling runs 6 months of the year here.

What drives the load in Placerville

Of the 36,500 BTU/hr, 18,720 comes through walls, roof and windows on a 101°F afternoon (51%), 13,000 is sun on the house (36%), 2,120 is four people and their appliances, and 2,700 is moisture the coil has to wring out of Placerville's summer air (7%).

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 Placerville

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,700 BTU/hr; a 350 sq ft living room needs about 6,400 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,000 BTU/hr.

Month by month in Placerville

Jul alone uses 30% of the year's cooling energy. The unit runs the equivalent of 664 hours a year at full output.

Placerville against nearby cities

Of 376 California cities here, Placerville has the 131st highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Placerville's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Placerville, 2.8 miles from the center of Placerville at 1,850 ft above sea level. That is close enough that the station's summers are Placerville's summers.

No other city in this set uses Placerville, so this sizing is Placerville's alone.

The sun over Placerville in late July

At 38.73°N, the noon sun on 21 July stands 71.7° above the horizon over Placerville and the day runs 14 h 19 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.

10,695 people live in Placerville, the 368th largest of the 376 California cities sized on this site. Coordinates used: 38.7311, -120.7977.

Placerville AC sizing questions