What size AC for Stuart, FL? 3.5 tons for 2,000 sq ft

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

3.5 tons central AC or heat pump, about 41,200 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.4 tons. This is one of the climates the chart was written for.

If a contractor quotes you more than 3.5 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 583 square feet in this climate. For a single room, size by the room: 20.6 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Stuart (0.5 mi away). Jul is the hottest month, averaging a high of 90.9°F and a low of 75.5°F, with about 81 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 6,352 kWh a year at SEER2 14.3, or roughly $973 at Florida's average residential rate of 15.32¢ per kWh. Cooling runs 12 months of the year here.

What drives the load in Stuart

Of the 41,200 BTU/hr, 16,560 comes through walls, roof and windows on a 98°F afternoon (40%), 13,000 is sun on the house (32%), 2,120 is four people and their appliances, and 9,500 is moisture the coil has to wring out of Stuart'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 31,680 BTU/hr before the moisture allowance.

Other house sizes in Stuart

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 3,100 BTU/hr; a 350 sq ft living room needs about 7,200 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 12,400 BTU/hr.

Month by month in Stuart

Jul alone uses 14% of the year's cooling energy. The unit runs the equivalent of 2,206 hours a year at full output.

Stuart against nearby cities

Of 173 Florida cities here, Stuart has the 95th highest cooling load. The range runs from Miami Shores at 36,500 BTU/hr to Plant City at 44,900.

Where Stuart's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Stuart, 0.5 miles from the center of Stuart at 13 ft above sea level. That is close enough that the station's summers are Stuart's summers.

No other city in this set uses Stuart, so this sizing is Stuart's alone.

The sun over Stuart in late July

At 27.20°N, the noon sun on 21 July stands 83.2° above the horizon over Stuart and the day runs 13 h 28 min from sunrise to sunset. With the sun that close to overhead, the roof takes most of the heat at midday and the west wall takes the rest after 3 pm. Shorter days give the house a longer night to shed the day's heat.

19,566 people live in Stuart, the 125th largest of the 173 Florida cities sized on this site. Coordinates used: 27.1953, -80.2441.

Stuart AC sizing questions