What size AC for Boulder City, NV? 5 tons for 2,000 sq ft

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

5 tons central AC or heat pump, about 55,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, which falls short here. On a design day the unit runs flat out and the house still drifts above 75°F by late afternoon.

If a contractor quotes you more than 5 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 435 square feet in this climate. For a single room, size by the room: 27.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Mccarran International Airport (21.1 mi away). Jul is the hottest month, averaging a high of 104.5°F and a low of 82°F, with about 137 days a year at 90°F or more. That gives a design temperature of 113°F against 75°F inside.

What it costs to run

About 5,844 kWh a year at SEER2 14.3, or roughly $781 at Nevada's average residential rate of 13.36¢ per kWh. Cooling runs 7 months of the year here.

What drives the load in Boulder City

Of the 55,200 BTU/hr, 27,360 comes through walls, roof and windows on a 113°F afternoon (50%), 13,000 is sun on the house (24%), 2,120 is four people and their appliances, and 12,700 is moisture the coil has to wring out of Boulder City's summer air (23%).

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 42,480 BTU/hr before the moisture allowance.

Other house sizes in Boulder City

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 4,100 BTU/hr; a 350 sq ft living room needs about 9,700 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 16,600 BTU/hr.

Month by month in Boulder City

Jul alone uses 24% of the year's cooling energy. The unit runs the equivalent of 1,513 hours a year at full output.

Boulder City against nearby cities

Of 10 Nevada cities here, Boulder City has the 2nd highest cooling load. The range runs from Carson at 30,700 BTU/hr to Henderson at 55,200.

Where Boulder City's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Mccarran International Airport, 21.1 miles from the center of Boulder City at 2,175 ft above sea level. That is close enough that the station's summers are Boulder City's summers.

1 other city uses the same station and get the same climate inputs. The closest to Boulder City: Henderson (13 mi away, 8.8 mi from the station). Boulder City is farther from the station than 1 of them.

The sun over Boulder City in late July

At 35.84°N, the noon sun on 21 July stands 74.6° above the horizon over Boulder City and the day runs 14 h 05 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.

15,029 people live in Boulder City, the 10th largest of the 10 Nevada cities sized on this site. Coordinates used: 35.8438, -114.9116.

Boulder City AC sizing questions