A ductless mini-split pairs an outdoor heat pump with one or more indoor units mounted in the rooms they serve. A refrigerant line set, a power and control cable and a condensate drain run between them through a hole about three inches across, so there is no ductwork to build. In San Leandro, San Lorenzo and Castro Valley the most common reasons to install one are a room addition, a converted garage, a home office or an upstairs room the original ducts never reached.
Where a mini-split makes sense
- No ductwork. Homes heated by a wall furnace or baseboard heaters, or with no cooling at all, can add heating and cooling one room at a time.
- Room additions. Extending the existing ducts often means weak airflow at the end of a long run or a furnace that was never sized for the extra space. A separate zone avoids both.
- Hot or cold rooms. A bedroom over the garage or a hillside room with big west-facing windows can get its own control instead of overheating or overcooling the rest of the house.
- Home offices. Cool the room you work in all day without running the whole-house system.
- Garages and workshops. A mini-split works well here once the walls, ceiling and door are reasonably insulated and sealed; without that, any system struggles.
Single-zone or multi-zone
| Single-zone | Multi-zone | |
|---|---|---|
| Setup | One outdoor unit, one indoor unit | One outdoor unit feeding two or more indoor units |
| Best for | One room or one open area | Several rooms where outdoor space is limited |
| If the outdoor unit fails | Only that room is affected | Every room on it loses heating and cooling |
| Sizing | Matched to one room | Each indoor unit matched to its room, and the outdoor unit to the combination |
Indoor unit styles
- Wall-mounted units are the most common and usually the least expensive. They sit high on the wall.
- Floor consoles sit low on the wall, which helps under windows, in rooms with sloped ceilings and for heating.
- Ceiling cassettes are recessed into the ceiling and need attic space above.
- Concealed ducted units hide in a ceiling or crawlspace and use short duct runs to serve two or three small rooms from one unit.
Sizing comes first
An oversized unit cycles on and off, removes less moisture and wears faster. An undersized one runs flat out on the warmest afternoons and still falls behind. We size each indoor unit from the room itself: floor area and ceiling height, insulation, the size and direction of the windows, and how the room is used. A square-footage rule of thumb misses the west-facing glass that makes one bedroom the hottest in the house.
What the installation includes
- Plan. Where each indoor unit goes, the line set route, the outdoor unit location on a ground pad or wall bracket, and whether the electrical panel has room for a new circuit.
- Mounting. The indoor unit is hung level on its mounting plate, the wall hole slopes outward so condensate drains, and the line set runs in a protective cover on the outside wall.
- Electrical. A dedicated circuit and an outdoor disconnect for the system.
- Leak test and vacuum. Flare connections are tightened to specification, the lines are pressure-tested with nitrogen and evacuated with a vacuum pump before the refrigerant is released. EPA-certified technicians handle the refrigerant.
- Start-up. We run both heating and cooling, check temperatures and drainage, and show you the remote and how to clean the filters.
What affects the price
Installed mini-splits typically run $2,500 to $6,000 per zone. Where a job lands depends on the capacity and style of the indoor unit (a cassette or concealed unit costs more than a wall unit), the length and route of the line set, whether the panel needs a new circuit or more space, wall-bracket mounting, and whether a condensate pump is needed where gravity drainage is not possible. You see the price before any work starts, and financing is available for installations. The HVAC installation cost guide covers installed costs more broadly.
Mini-split or a central heat pump?
If the house already has sound ductwork, a ducted heat pump can serve every room with one system. Mini-splits make the most sense where ducts are missing, too small or not worth extending, and many homes end up with both: central heating and cooling for the main floor and a mini-split for the addition. If you are comparing equipment, see our notes on Mitsubishi, Daikin, Fujitsu and LG.
Looking after it
Rinse the washable filters in each indoor unit every few weeks during heavy use, keep plants and debris clear of the outdoor unit, and book a yearly cleaning of the coil and blower wheel. Musty smells, water dripping from the indoor unit or a blinking error light are signs it needs mini-split repair.
Local notes
Mornings near the bay are often cool and foggy, the warmest afternoons arrive in late summer and early fall, and heating is needed mostly from November to March. That mild range suits mini-splits well. Hillside homes, including those in Bay-O-Vista, often have one or two sun-loaded rooms that a single central thermostat cannot keep comfortable, and that is where a ductless zone pays off most.