What size AC for Longview, WA? 2 tons for 2,000 sq ft

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

2 tons central AC or heat pump, about 23,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 81% 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 1,034 square feet in this climate. For a single room, size by the room: 11.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Longview (0.9 mi away). Aug is the hottest month, averaging a high of 80.4°F and a low of 53.3°F, with about 10 days a year at 90°F or more. That gives a design temperature of 85°F against 75°F inside.

What it costs to run

About 305 kWh a year at SEER2 14.3, or roughly $44 at Washington's average residential rate of 14.42¢ per kWh. Cooling runs 2 months of the year here.

What drives the load in Longview

Of the 23,200 BTU/hr, 7,200 comes through walls, roof and windows on a 85°F afternoon (31%), 13,000 is sun on the house (56%), 2,120 is four people and their appliances, and 900 is moisture the coil has to wring out of Longview'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 22,320 BTU/hr before the moisture allowance.

Other house sizes in Longview

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 1,700 BTU/hr; a 350 sq ft living room needs about 4,100 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 7,000 BTU/hr.

Month by month in Longview

Aug alone uses 37% of the year's cooling energy. The unit runs the equivalent of 188 hours a year at full output.

Longview against nearby cities

Of 91 Washington cities here, Longview has the 24th highest cooling load. The range runs from Burlington at 15,700 BTU/hr to Kennewick at 32,900.

Where Longview's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Longview, 0.9 miles from the center of Longview at 11 ft above sea level. That is close enough that the station's summers are Longview's summers.

1 other city uses the same station and get the same climate inputs. The closest to Longview: Kelso (4 mi away, 4.6 mi from the station). Longview sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Longview in late July

At 46.15°N, the noon sun on 21 July stands 64.3° above the horizon over Longview and the day runs 15 h 02 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. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

38,294 people live in Longview, the 33rd largest of the 91 Washington cities sized on this site. Coordinates used: 46.1457, -122.9643.

Longview AC sizing questions