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

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

3.5 tons central AC or heat pump, about 37,400 BTU/hr of load

Here the 20 BTU per square foot chart lands close: 3.5 tons against a load of 3.1 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 641 square feet in this climate. For a single room, size by the room: 18.7 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Miami WSO City (6.9 mi away). Aug is the hottest month, averaging a high of 88.7°F and a low of 79.1°F, with about 29 days a year at 90°F or more. That gives a design temperature of 94°F against 75°F inside.

What it costs to run

About 7,233 kWh a year at SEER2 14.3, or roughly $1,108 at Florida's average residential rate of 15.32¢ per kWh. Cooling runs 12 months of the year here.

What drives the load in Palmetto Bay

Of the 37,400 BTU/hr, 13,680 comes through walls, roof and windows on a 94°F afternoon (37%), 13,000 is sun on the house (35%), 2,120 is four people and their appliances, and 8,600 is moisture the coil has to wring out of Palmetto Bay'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 28,800 BTU/hr before the moisture allowance.

Other house sizes in Palmetto Bay

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,800 BTU/hr; a 350 sq ft living room needs about 6,500 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 11,200 BTU/hr.

Month by month in Palmetto Bay

Jul alone uses 13% of the year's cooling energy. The unit runs the equivalent of 2,763 hours a year at full output.

Palmetto Bay against nearby cities

Of 173 Florida cities here, Palmetto Bay has the 161st highest cooling load. The range runs from Miami Shores at 36,500 BTU/hr to Plant City at 44,900.

Where Palmetto Bay's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Miami WSO City, 6.9 miles from the center of Palmetto Bay at 15 ft above sea level. That is close enough that the station's summers are Palmetto Bay's summers.

4 other cities use the same station and get the same climate inputs. The closest to Palmetto Bay: Pinecrest (3 mi away, 3.8 mi from the station), Coral Gables (6 mi away, 2.7 mi from the station), South Miami (6 mi away, 0.9 mi from the station), Key Biscayne (11 mi away, 7.5 mi from the station). Palmetto Bay is farther from the station than 3 of them.

The sun over Palmetto Bay in late July

At 25.62°N, the noon sun on 21 July stands 84.8° above the horizon over Palmetto Bay and the day runs 13 h 22 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.

25,402 people live in Palmetto Bay, the 103rd largest of the 173 Florida cities sized on this site. Coordinates used: 25.6217, -80.3189.

Palmetto Bay AC sizing questions