Ductless Mini-Split

Perfect for older Bay Area homes that can’t run new ductwork

Brands we service: Mitsubishi Electric See all brands we service →

For an existing unit with a fault, see mini-split repair.

A ductless mini-split is a heat pump that skips the ducts. The outdoor condenser connects to one or more indoor air handlers through a small refrigerant line set. Each handler controls its own zone. For a 1940s Oakland bungalow, a 1960s Berkeley Craftsman, or a Danville bonus room, this is usually the right answer.

If you’re looking at this because a room stays stuffy, or allergies:

Here’s the honest version, not the sales version. A ducted system pushes air through ductwork that often runs through an attic or crawlspace; any leak in that ductwork pulls in dust, insulation fibers, and outside air along the way. A mini-split skips that: air moves inside the room, through the indoor unit’s washable filter, and back into the room, with no duct run to leak through. That does not make it a medical air purifier and we are not going to claim it cures allergies, but it does give that room a cleaner, closed loop, and you can run the fan to keep air moving without heating or cooling the rest of the house to do it. Zoning also means if one bedroom is the problem room, you size and run just that zone, not the whole house’s system.

What installation actually looks like, day by day:

For a single-zone job, most installs finish in one day: morning is mounting the indoor unit and running the line set; midday the outdoor unit goes in and gets its electrical connection, then we vacuum and leak-test the line set before any refrigerant goes in; by afternoon the system is charged, tested, and we walk you through the remote and filter access before we leave. For 2 or more zones, plan on a second day: day one covers the outdoor unit, electrical, and line sets to each indoor location, and day two is mounting the remaining indoor units followed by the same vacuum, charge, and test sequence.

How an inverter mini-split holds a room steady:

The reason a good mini-split keeps a room within a degree comes down to the inverter. Instead of a compressor that slams on at full power and then shuts off, the outdoor unit runs a variable-speed DC compressor that modulates from roughly 30 percent up to 100 percent. Sensors on the indoor coil, the room, the outdoor coil, and the compressor discharge feed the inverter board, which trims output continuously. You get small, steady corrections instead of the temperature swings you feel from a single-stage furnace and AC. That same modulation is why these systems run quiet and why they sip power at part load, which is most of the time.

Indoor styles and crossover options:

A mini-split is not only a wall unit. The same outdoor condenser can drive a high-wall head, a ceiling cassette, a slim floor console, or a compact ducted air handler tucked into a closet or soffit. On a crossover setup we can also pair an inverter outdoor unit with a furnace coil through a low-voltage interface, so a home keeps its existing ductwork and still gains inverter heating and cooling. We match the indoor style to each room at the estimate.

Common use cases:

• Historic homes with plaster walls
• Rooms that existing HVAC can’t reach (upstairs bedrooms, bonus rooms, additions, garages, ADUs)
• One room that matters more than the rest: a home office, a nursery, the primary bedroom, a garage gym, a sunroom or a finished attic
• Whole-home solution for houses without existing ductwork
• Climate zoning so different rooms can hold different temperatures
• Rebate-eligible heat pump replacement strategy

Pricing:

A Mitsubishi Electric ductless system usually runs about $5,500 to $9,000 for each room or zone, depending on the home. The number of indoor units, total capacity, panel capacity, line-set routing, the series (Hyper-Heat models cost more) and the controls you choose all move it.

The on-site assessment for a ductless installation or replacement is free and takes about 60 to 90 minutes. We confirm the number of zones, equipment, line-set routing, and electrical scope, then provide a written project estimate after the visit. If more than one person makes the decision, it helps to have everyone there.

On running costs, Mitsubishi Electric says its zoned systems are up to 40% more efficient than conventional heating and air conditioning systems. Your savings depend on the house and how you run it, so we don’t promise a number.

More answers on cost, noise, cold-weather heating and the assessment are in our Mitsubishi ductless FAQ. How the 5, 10 and 12-year warranty levels work is in our Mitsubishi warranty guide.

Multi-zone design notes:

A multi-zone mini-split is not just one outdoor unit with more lines. Total indoor capacity should not exceed outdoor capacity by more than 130 percent; go higher and the system short-cycles. Pipe lengths matter too. Long horizontal runs need oil traps. Vertical drops over 23 feet need additional consideration. We size and route every install to manufacturer spec, not by rule of thumb.

New mini-splits are moving off R-410A to lower-GWP refrigerants, R-454B or R-32 depending on the equipment line, so we check the data plate before we charge anything. We charge each system to manufacturer weight, then verify it by superheat or subcooling and leak-test the line set before we call an install finished.

Why a mini-split install lives or dies on the details:

A mini-split does not braze together the way a central system does. The indoor and outdoor units join through flare fittings, and a flare that is over-tightened, under-tightened, or cut sloppily will weep refrigerant for years. We cut and seat every flare clean, torque it to the manufacturer’s spec, then pull a deep vacuum and confirm it holds with a micron gauge and a standing vacuum test before any refrigerant goes in. Skip that and you trap moisture in the line set, and moisture is what turns into acid and kills a compressor.

The outdoor unit also ships pre-charged for a standard line length. Run the line set longer and the system needs additional refrigerant weighed in by the foot. Plenty of bargain installs skip that top-off, which is exactly why a brand-new mini-split can run weak from day one. We measure the actual run and charge for it.

Electrical reality:

A single-zone install often runs on existing 220V capacity if the house has a free breaker. Larger multi-zone systems (3+ zones) usually want a dedicated 30A or 50A circuit. Older Bay Area homes (1940s to 60s) sometimes max out their panel before HVAC is added. We include an electrical capacity check at the estimate. If a sub-panel is needed, we coordinate with a licensed electrician.

Noise expectations:

Indoor-unit sound levels depend on the model and fan setting. We compare the Mitsubishi Electric model specifications for the rooms we are sizing. Outdoor condensers start around 46 dB(A) and climb with load, which matters for HOA-restricted yards and shared walls. We talk through placement at the estimate.

Before your service visit

• Mitsubishi Mini-Split Repair: What Each Symptom Points To
• Daikin Mini Split Flashing Blue Light: Identify the Lamp First
• Mitsubishi Operation Light Blinking: Standby or a Fault?
• Mitsubishi Mini Split Leaking Water Indoors: Stop and Check the Location

Plan your Mitsubishi installation

• Replacing a furnace and AC
• Finished garage
• Detached ADU, studio or shed office
• Refinished basement
• Indoor unit styles
• intelli-HEAT with a gas furnace

What makes us different

Mitsubishi Electric Diamond Contractor. We install Mitsubishi Electric ductless systems and register eligible M-Series and P-Series equipment for the manufacturer's limited warranty. We also repair and service existing mini-splits from other brands.

Proper zone sizing. We size every zone based on heat loss calculation, not rule of thumb. Properly sized systems run quieter, last longer, and control humidity better.

Owner reviews every install. Every estimate gets my personal review before it reaches you. For installations and complex service, I meet you on-site. For routine calls, our trained technicians arrive with my license number on the invoice.

What to expect

Every job, repair or install, follows the same rhythm. No upsells dressed as "package tiers." No "today only" pricing. If the answer is "wait six months and re-evaluate," that is what we will say.

1. 01
   Assess the installation

   An on-site installation assessment is free. We review the existing equipment, space, ductwork, and electrical capacity for the proposed system.

2. 02
   Review the written quote

   The itemized quote identifies the equipment and installation scope, based on the home measurements and load calculation. Confirm any incentive eligibility before approving the project.

3. 03
   Plan and install

   After approval, we confirm equipment availability, schedule the work, and arrange required permits. Changes to the agreed scope need your approval.

4. 04
   Commission the system

   We check operation and explain the controls. Eligible Mitsubishi M-Series and P-Series systems registered through a Diamond Contractor receive 12-year parts and compressor coverage; HM, WR, HX and WX are limited to 10 years. See the Mitsubishi FAQ below for registration and eligibility terms. Our 2-year labor warranty extends to 10 years with an active maintenance plan, subject to its written terms. Manufacturer coverage excludes labor.

The diagnostic is ninety-nine dollars and we credit it toward the repair. If the answer is ‘your system is fine, here are the logs, call us next year,’ that is what the estimate will say.

Ductless Mini-Split: common questions

Cities where we do this work

Tier-1 service area for ductless mini-split: Danville · San Ramon · Alamo · Blackhawk · Pleasanton · Dublin · Walnut Creek · Lafayette · Alameda · Piedmont · Pleasant Hill · Atherton · Hillsborough · Los Altos Hills · Burlingame · Millbrae .

Also across the Bay Area: Livermore · Concord · Orinda · Moraga · Martinez · San Jose · Santa Clara · Cupertino · Los Gatos · Saratoga · Sunnyvale · Mountain View · Palo Alto · Los Altos · Menlo Park · Oakland · Berkeley · Richmond · El Cerrito · Albany · Fremont · Hayward · Union City · Newark · San Leandro · Castro Valley · Milpitas · Woodside · Portola Valley · Daly City · South San Francisco · San Bruno · Pacifica · San Mateo · Foster City · Belmont · San Carlos · Redwood City · East Palo Alto · Half Moon Bay · Vallejo · Benicia · Hercules · Pinole · Rodeo · El Sobrante · San Pablo · Emeryville · Clayton . See full service area.