What size AC do I need in Altamonte Springs?
Size comes from a room-by-room load calculation (ACCA Manual J), not from square feet per ton. It matters more here than in a dry climate: at about 75% average humidity, an oversized system short-cycles and leaves a home cold and clammy. The citywide median living area is only 1,325 sq ft.
Not by square foot per ton
Ask for the Manual JThe rule of thumb you will be quoted — so many square feet per ton — is a sales tool, not a calculation. It ignores orientation, glazing, insulation, infiltration, ceiling height, duct location and internal gains, all of which vary enormously across a city whose housing was built over five decades.
The method is a room-by-room load calculation (ACCA Manual J) and equipment selection against it (Manual S). Ask which was done and ask to see the output. A contractor who sized your system by walking the house and naming a tonnage has guessed.
What the parcel record says about the homes here
Seminole County Property AppraiserWhat can be stated from the record is the size of the stock the calculation gets applied to. Across all 13,253 improved residential parcels in the city, the median living area is 1,325 sq ft. That is small, and it is small because 61.65% of the city's units are multi-family.
The spread inside the twenty largest platted communities runs from a median of 496 sq ft at Waterside at Cranes Roost to 1,849 sq ft in the Spring Oaks units. Those are not variations on one job. They are different machines in different places.
Seminole County Property Appraiser CAMA extract (Parcels.csv, 5 September 2026), tax district A1 — Altamonte Springs. 13,253 improved residential parcels: single-family, townhome and condominium. Apartments and manufactured homes excluded.
Oversizing is the local failure mode
Latent load needs run timeIn a dry climate an oversized system is merely wasteful. Here it is a comfort problem, because removing humidity takes run time. Average relative humidity runs about 75% and rainfall about 51.5 inches a year. A system with too much capacity satisfies the thermostat quickly, shuts off, and never runs long enough to pull the latent load out of the air.
The result is a house or a unit that is cold and clammy rather than dry — and a homeowner who turns the thermostat down further, which makes it worse. Small attached units are the most exposed to this, and small attached units are the majority of this city's housing.
NOAA 1991–2020 US Climate Normals, Orlando International Airport (USW00012815).
Duct changes the answer
Test first, size secondA load calculation tells you what the house needs. The duct decides what actually arrives. In a city where 34.59% of housing was built in the 1970s and 37.11% in the 1980s, the trunk line is frequently older than the last two systems put together.
Sizing new equipment up to compensate for leaking duct is the wrong fix and makes the humidity problem worse. Test the duct — Duke Energy lists an instant rebate of up to $450 for duct test and repair — then size the equipment.
City of Altamonte Springs CITY PLAN 2030, Housing Element DIA, Table 3.4. Duke figure: Duke Energy news release, 9 June 2025.