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

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

2 tons central AC or heat pump, about 20,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 108% 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 1,187 square feet in this climate. For a single room, size by the room: 10.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Hayward Air Terminal (2.4 mi away). Sep is the hottest month, averaging a high of 77°F and a low of 57.6°F, with about 9 days a year at 90°F or more. That gives a design temperature of 81°F against 75°F inside.

What it costs to run

About 461 kWh a year at SEER2 14.3, or roughly $150 at California's average residential rate of 32.58¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in Hayward

Of the 20,200 BTU/hr, 4,320 comes through walls, roof and windows on a 81°F afternoon (21%), 13,000 is sun on the house (64%), 2,120 is four people and their appliances, and 800 is moisture the coil has to wring out of Hayward's summer air (4%).

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 19,440 BTU/hr before the moisture allowance.

Other house sizes in Hayward

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,500 BTU/hr; a 350 sq ft living room needs about 3,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 6,100 BTU/hr.

Month by month in Hayward

Sep alone uses 26% of the year's cooling energy. The unit runs the equivalent of 326 hours a year at full output.

Hayward against nearby cities

Of 376 California cities here, Hayward has the 323rd highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Hayward's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Hayward Air Terminal, 2.4 miles from the center of Hayward at 31 ft above sea level. That is close enough that the station's summers are Hayward's summers.

2 other cities use the same station and get the same climate inputs. The closest to Hayward: Union City (5 mi away, 6.8 mi from the station), San Leandro (6 mi away, 3.8 mi from the station). Hayward sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Hayward in late July

At 37.63°N, the noon sun on 21 July stands 72.8° above the horizon over Hayward and the day runs 14 h 13 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.

158,440 people live in Hayward, the 36th largest of the 376 California cities sized on this site. Coordinates used: 37.6268, -122.1040.

Hayward AC sizing questions