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For a mini-split installation in San Francisco County, the contractor's load calculation starts and ends with heat. Homes in San Francisco County, CA have essentially no cooling season — no month of the year is warm enough to call for it. The compressor and refrigerant circuit will run in heating mode through the cold months, and the outdoor unit's low-temperature capacity sets the floor on what size will actually keep the house comfortable. Cooling capacity on the spec sheet is nearly irrelevant here. A contractor who quotes a system without doing a proper heating-load calculation for this specific address is guessing, and the homeowner ends up with a unit that either short-cycles or runs flat out on cold nights.
Older wiring in a house carries a fixed capacity, and a mini-split draw that fits easily on a newer panel can run right up against what a prewar service box will give. Half the homes in San Francisco County, California were built in 1946 or earlier (2020-2024 ACS 5-year). That puts the electrical assessment ahead of equipment selection on most jobs here: a contractor who skips it will quote a unit and then discover the panel work changes the price. Ductwork is not a factor with mini-splits, but the electrical infrastructure behind the walls is, and in stock like this it gets opened and measured first.
What a Mini-split Looks Like Once It's In
The indoor unit mounts high on an interior wall of the room being served, blowing conditioned air directly into that space. The outdoor unit sits on the ground or on a bracket fixed to an exterior wall, housing the compressor and the components that do the heavy mechanical work of the system.
A conduit bundled with refrigerant lines, a power cable, and a condensate drain runs through a small hole in the wall to connect the two units. Where a home takes more than one indoor unit, each connects back to the same outdoor unit through its own conduit run.
The drawing shows a typical layout, and a licensed contractor determines exactly how the system fits the construction of this particular house.
Get matched in San Francisco CountySan Francisco County, by the numbers
66 severe weather events were recorded in San Francisco County, California between 2015 and 2024.
NOAA National Centers for Environmental Information, Storm Events Database, bulk CSV export, events 2015-01-01 through 2024-12-31.Half the homes in San Francisco County, California were built in 1946 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesSan Francisco County, California holds 414,602 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 38.2% of the occupied homes in San Francisco County, California (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesCodes & Standards for Mini-Split Installation in San Francisco County, California1 sourced rules & standards
Licensing and Legal Requirements in San Francisco County, California
California requires a state contractor license: it is a misdemeanour to engage in the business of, or act in the capacity of, a contractor in California without one, unless the work is exempt.
Severe Weather Events in San Francisco County
Extreme weather puts real demands on heating and cooling equipment, and those demands vary by where you live. A mini-split sized and installed for local conditions handles the work San Francisco County actually throws at it.
66 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.