A ductless mini-split is a heat pump in two parts: an outdoor unit and one or more indoor units, joined by refrigerant lines, a drain and a power cable that pass through a small hole in the wall. In Tiburon, Belvedere and Mill Valley it is the usual answer when a home has no ducts, when an addition or converted garage was never connected to the central system, or when a view room with west-facing glass overheats on sunny afternoons while the rest of the house is fine.
Where mini-splits fit
- Homes without ducts. Houses heated by radiant floors, baseboards or wall heaters can add cooling and efficient heating without opening walls for ductwork.
- Additions, garages and studios. Stretching old ducts to a new space rarely works well; a dedicated unit does.
- Rooms that never match the thermostat. An upstairs bedroom or a glass-walled living room gets its own control.
- Older homes with little spare space. No room for a furnace, or for ducts in a shallow crawlspace? A wall unit needs neither.
Choosing indoor units
| Type | Where it works | Trade-offs |
|---|---|---|
| Wall-mounted | Bedrooms, living rooms, offices | Simplest and most efficient; visible on the wall |
| Floor console | Under windows, rooms with sloped ceilings | Good for heating; takes a little floor space |
| Ceiling cassette | Rooms with an accessible cavity above the ceiling | Discreet; needs space overhead |
| Ducted (concealed) | Two or three nearby rooms, or where no unit should show | Only grilles are visible; needs room in a closet, attic or soffit |
Ducted mini-splits are worth a look in finished rooms where a wall unit would feel out of place.
Sizing and zones
Each indoor unit is sized for its own room, from the floor area, windows, exposure and insulation. A large unit in a small bedroom is a common mistake: it overshoots, cycles and is noisier than it needs to be. With several rooms, the choice is between one multi-zone outdoor unit and separate single-zone systems. Multi-zone needs one outdoor location and less wall space outside; single-zone systems keep each room independent, so one outdoor failure does not take out every room. When a home could go either way, we lay out both.
Routing lines and placing the outdoor unit
The refrigerant lines, drain and cable leave each indoor unit through the wall and run to the outdoor unit, inside a wall or attic where possible or in a paintable line-set cover outside. The condensate needs a path downhill or a small pump. The outdoor unit goes where it has airflow, a solid pad or wall bracket and room for service, and where its sound will not bother bedrooms or neighbors. Homeowner associations on the peninsula often have rules about exterior equipment, so the location is agreed before installation day.
How the installation goes
- Assessment. We look at the rooms, walls, electrical panel and outdoor locations with you.
- Design. Unit types, sizes and line routes, laid out for your approval.
- Proposal. A detailed written proposal with the price upfront.
- Install. Units mounted, lines run and pressure-tested, the system evacuated with a vacuum pump and started. Most homes take one to two days.
- Training. We show you the remote’s modes and schedules and how to rinse the filters.
Local notes
Mill Valley’s older houses, built from the early 1900s to the 1960s, often have crawlspace ducts never sized for cooling, or no ducts at all, so mini-splits and heat pumps are the common upgrade there. On the Tiburon peninsula, outdoor units near the water do better in a spot sheltered from the salt wind. See mini-split installation in Mill Valley, Tiburon and Belvedere, compare with a central heat pump installation, and for systems you already own see mini-split repair. Brand pages such as Mitsubishi and Fujitsu cover individual equipment lines.