What size AC for Pasco, WA? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 32,900 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 27% 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 728 square feet in this climate. For a single room, size by the room: 16.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Pasco Tri Cities Airport (0.3 mi away). Jul is the hottest month, averaging a high of 92.5°F and a low of 56.9°F, with about 55 days a year at 90°F or more. That gives a design temperature of 98°F against 75°F inside.

What it costs to run

About 990 kWh a year at SEER2 14.3, or roughly $143 at Washington's average residential rate of 14.42¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in Pasco

Of the 32,900 BTU/hr, 16,560 comes through walls, roof and windows on a 98°F afternoon (50%), 13,000 is sun on the house (40%), 2,120 is four people and their appliances, and 1,300 is moisture the coil has to wring out of Pasco's summer air (4%).

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 31,680 BTU/hr before the moisture allowance.

Other house sizes in Pasco

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 9,900 BTU/hr.

Month by month in Pasco

Jul alone uses 39% of the year's cooling energy. The unit runs the equivalent of 430 hours a year at full output.

Pasco against nearby cities

Of 91 Washington cities here, Pasco has the 2nd highest cooling load. The range runs from Burlington at 15,700 BTU/hr to Kennewick at 32,900.

Where Pasco's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Pasco Tri Cities Airport, 0.3 miles from the center of Pasco at 400 ft above sea level. That is close enough that the station's summers are Pasco's summers.

3 other cities use the same station and get the same climate inputs. The closest to Pasco: Kennewick (5 mi away, 5.7 mi from the station), Richland (8 mi away, 8.5 mi from the station), West Richland (13 mi away, 13.2 mi from the station). Pasco sits closer to the station than any of them, so its numbers are the best measured of the group.

The sun over Pasco in late July

At 46.27°N, the noon sun on 21 July stands 64.1° above the horizon over Pasco and the day runs 15 h 03 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.

81,724 people live in Pasco, the 17th largest of the 91 Washington cities sized on this site. Coordinates used: 46.2661, -119.1214.

Pasco AC sizing questions