What size AC for Poway, CA? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 33,400 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 26% 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 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 718 square feet in this climate. For a single room, size by the room: 16.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Ramona Airport (7 mi away). Aug is the hottest month, averaging a high of 90.8°F and a low of 58.7°F, with about 62 days a year at 90°F or more. That gives a design temperature of 97°F against 75°F inside.

What it costs to run

About 1,249 kWh a year at SEER2 14.3, or roughly $407 at California's average residential rate of 32.58¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Poway

Of the 33,400 BTU/hr, 15,840 comes through walls, roof and windows on a 97°F afternoon (47%), 13,000 is sun on the house (39%), 2,120 is four people and their appliances, and 2,500 is moisture the coil has to wring out of Poway'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 30,960 BTU/hr before the moisture allowance.

Other house sizes in Poway

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,500 BTU/hr; a 350 sq ft living room needs about 5,800 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,000 BTU/hr.

Month by month in Poway

Aug alone uses 32% of the year's cooling energy. The unit runs the equivalent of 534 hours a year at full output.

Poway against nearby cities

Of 376 California cities here, Poway has the 149th highest cooling load. The range runs from Corte Madera at 15,700 BTU/hr to Palm Desert at 59,000.

Where Poway's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Ramona Airport, 7 miles from the center of Poway at 1,385 ft above sea level. That is close enough that the station's summers are Poway's summers.

1 other city uses the same station and get the same climate inputs. The closest to Poway: Escondido (10 mi away, 11.3 mi from the station). Poway sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Poway in late July

At 32.99°N, the noon sun on 21 July stands 77.4° above the horizon over Poway and the day runs 13 h 52 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.

49,435 people live in Poway, the 181st largest of the 376 California cities sized on this site. Coordinates used: 32.9877, -117.0218.

Poway AC sizing questions