What size AC for Brigham City, UT? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 31,500 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 34% 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 763 square feet in this climate. For a single room, size by the room: 15.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Brigham City Waste Plt (1.3 mi away). Jul is the hottest month, averaging a high of 91°F and a low of 57.5°F, with about 45 days a year at 90°F or more. That gives a design temperature of 96°F against 75°F inside.

What it costs to run

About 884 kWh a year at SEER2 14.3, or roughly $117 at Utah's average residential rate of 13.19¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in Brigham City

Of the 31,500 BTU/hr, 15,120 comes through walls, roof and windows on a 96°F afternoon (48%), 13,000 is sun on the house (41%), 2,120 is four people and their appliances, and 1,200 is moisture the coil has to wring out of Brigham City'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 30,240 BTU/hr before the moisture allowance.

Other house sizes in Brigham City

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,400 BTU/hr; a 350 sq ft living room needs about 5,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 9,400 BTU/hr.

Month by month in Brigham City

Jul alone uses 41% of the year's cooling energy. The unit runs the equivalent of 402 hours a year at full output.

Brigham City against nearby cities

Of 67 Utah cities here, Brigham City has the 65th highest cooling load. The range runs from Heber at 30,700 BTU/hr to St. George at 49,200.

Where Brigham City's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Brigham City Waste Plt, 1.3 miles from the center of Brigham City at 4,240 ft above sea level. That is close enough that the station's summers are Brigham City's summers.

No other city in this set uses Brigham City Waste Plt, so this sizing is Brigham City's alone.

The sun over Brigham City in late July

At 41.51°N, the noon sun on 21 July stands 68.9° above the horizon over Brigham City and the day runs 14 h 34 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.

20,319 people live in Brigham City, the 47th largest of the 67 Utah cities sized on this site. Coordinates used: 41.5059, -112.0514.

Brigham City AC sizing questions