What size AC for Lake Havasu City, AZ? 5 tons for 2,000 sq ft

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

5 tons central AC or heat pump, about 59,000 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 407 square feet in this climate. For a single room, size by the room: 29.5 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Lake Havasu City (2.8 mi away). Jul is the hottest month, averaging a high of 109.3°F and a low of 82.7°F, with about 178 days a year at 90°F or more. That gives a design temperature of 117°F against 75°F inside.

What it costs to run

About 7,105 kWh a year at SEER2 14.3, or roughly $1,091 at Arizona's average residential rate of 15.36¢ per kWh. Cooling runs 8 months of the year here.

What drives the load in Lake Havasu City

Of the 59,000 BTU/hr, 30,240 comes through walls, roof and windows on a 117°F afternoon (51%), 13,000 is sun on the house (22%), 2,120 is four people and their appliances, and 13,600 is moisture the coil has to wring out of Lake Havasu 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 45,360 BTU/hr before the moisture allowance.

Other house sizes in Lake Havasu City

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 4,400 BTU/hr; a 350 sq ft living room needs about 10,300 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 17,700 BTU/hr.

Month by month in Lake Havasu City

Jul alone uses 21% of the year's cooling energy. The unit runs the equivalent of 1,723 hours a year at full output.

Lake Havasu City against nearby cities

Of 44 Arizona cities here, Lake Havasu City has the 3rd highest cooling load. The range runs from Flagstaff at 24,000 BTU/hr to Bullhead City at 60,800.

Where Lake Havasu City's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Lake Havasu City, 2.8 miles from the center of Lake Havasu City at 449 ft above sea level. That is close enough that the station's summers are Lake Havasu City's summers.

No other city in this set uses Lake Havasu City, so this sizing is Lake Havasu City's alone.

The sun over Lake Havasu City in late July

At 34.50°N, the noon sun on 21 July stands 75.9° above the horizon over Lake Havasu City and the day runs 13 h 58 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.

59,037 people live in Lake Havasu City, the 20th largest of the 44 Arizona cities sized on this site. Coordinates used: 34.4998, -114.3109.

Lake Havasu City AC sizing questions