If your home already has working ductwork, sealing or repairing it is almost always cheaper than ripping it out for a ductless system. If your home was never built with ducts at all — think Cupertino’s Eichler tract homes — ductless usually wins by default, because there’s nothing to connect a central system to in the first place.
Ductwork is a network of sheet-metal or flexible ducts that carries conditioned air from one central air handler to every room in the house. Ductless — also called a mini-split — skips the ducts entirely: one outdoor condenser connects by refrigerant line to one or more wall-mounted indoor units, each independently controlled. Neither is universally better; the right one depends on what’s already in your walls.
Key Takeaways
- If your ductwork already exists and is in reasonable shape, sealing or repairing it is almost always cheaper than switching to ductless.
- If your home has no ductwork at all — like the Eichler tract homes concentrated in Cupertino, Sunnyvale, Palo Alto, and Mountain View — ductless is usually the only realistic retrofit option.
- Ductless gives you independent room-by-room control; ducted systems distribute one setting per zone from a central air handler.
- Duct sealing typically runs $1,000-$2,500; a single-zone ductless install typically runs $4,500-$9,000 — the right comparison depends on what you’re actually replacing.
Not sure which applies to your home? Call (408) 733-2000 for a quick assessment.
Table of contents
- What’s actually different
- When ductwork wins
- When ductless wins
- Cost comparison
- Why Cupertino’s Eichler homes almost always go ductless
- FAQs
What’s actually different
Ductwork is the circulatory system of a central HVAC setup — sheet-metal or flexible ducts running through your attic, walls, or crawl space, carrying air from one central air handler to a supply vent in every room. It’s invisible once installed, and it’s what lets one thermostat manage the whole house.
A ductless mini-split skips all of that. One outdoor condenser connects via a thin refrigerant line — usually run through a small hole in an exterior wall — to one or more wall-mounted (or ceiling-cassette) indoor units. Each indoor unit uses inverter technology (a variable-speed compressor that modulates output to match demand) and has its own remote or thermostat, so a bedroom and a living room can run at completely different temperatures off the same outdoor unit.
When ductwork wins
- You already have ducts in decent shape: sealing leaks and adding a modern air handler is almost always cheaper than tearing out a working system.
- You want zero visible equipment indoors: vents are far less noticeable than wall-mounted indoor units in every room.
- You’re planning whole-home filtration upgrades: adding a MERV 13 filter or a whole-home air cleaner is simpler when there’s already a duct system to build it into.
When ductless wins
- Your home has no ductwork to begin with: retrofitting full ducts into a home never built for them is invasive and expensive — ductless sidesteps the problem entirely.
- You’re cooling a room addition or ADU: extending existing ductwork to a detached or newly built space is often impractical; a dedicated ductless unit is simpler.
- You want real room-by-room control: a multi-zone ductless setup lets each room run independently — see our multi-zone vs. single-zone comparison for how to size that out.
Cost comparison
| Approach | Typical cost | Best for |
|---|---|---|
| Duct sealing / repair | $1,000-$2,500 | Existing ducts with leaks, not full failure |
| Full duct replacement | Varies widely by home size and access | Ducts that are damaged, undersized, or contaminated beyond repair |
| Single-zone ductless | $4,500-$9,000 | One room, ADU, or addition with no ducts |
| Multi-zone ductless (2-3 zones) | $9,500-$16,000 | A home with no ducts needing several rooms covered |
Full duct-replacement cost depends heavily on your home’s size, attic or crawl-space access, and how much of the existing system can be reused — it’s not a number we’ll guess at here. Our full ductwork cost guide breaks down the real line items, and rebate eligibility for either path is worth checking on our current rebate guide before you commit either way. Want an exact estimate for your home? Call (408) 733-2000 — we’ll price it out with no obligation.
Not Sure Which Fits Your Home?
Why Cupertino’s Eichler homes almost always go ductless
Eichler homes — the mid-century tract homes concentrated in Cupertino, along with pockets of Sunnyvale, Palo Alto, and Mountain View — were built on a concrete slab with radiant floor heat, not a forced-air furnace. That means there’s no attic ductwork run and often no attic space to retrofit one into at all. When an Eichler homeowner in Cupertino wants air conditioning for the first time, ductless isn’t the “alternative” option — for most of these homes, it’s the only realistic one.
This is also why ENERGY STAR’s overview of ductless systems specifically calls out slab-on-grade homes without existing ducts as a strong fit for mini-splits. Our own Mitsubishi ductless install in a Sunnyvale Eichler home walks through exactly this scenario — open floor plan, no ducts, and a mini-split that solved both problems without touching the slab.
For over 25 years, Air & Plumbing Systems (CSLB #901246) has installed both ducted and ductless systems across the Bay Area, so the recommendation you get is based on your home’s actual construction — not which system happens to be easier for us to quote.
FAQs
Not automatically — it depends on what you’re comparing. Sealing existing, working ductwork ($1,000-$2,500) is almost always cheaper than a ductless install. But if your ductwork needs full replacement, or doesn’t exist at all, ductless often ends up the more cost-effective path since you’re not paying to tear out and rebuild a duct system.
Yes — this is common for a room addition, a converted garage, or a bonus room that the existing ducted system can’t reach well. You keep central ducted comfort for the main house and add a dedicated ductless unit just for the problem room.
You can reach our team at (408) 733-2000 for a free, no-obligation assessment. We’ll take a look at your existing setup — or lack of one — and recommend whether sealing your ducts or switching to ductless makes more sense for your home.
A single-zone install typically takes about a day; a multi-zone system covering several rooms usually takes 2-3 days, depending on how many indoor units are involved and how the refrigerant lines need to be routed around the home’s slab construction.
Both are possible. A single-zone system covers one room well. A multi-zone system connects one outdoor unit to several indoor units — up to 5-8 on residential systems — and can cover an entire home when it’s properly sized to the total square footage.
Generally yes — most California cities require a mechanical and electrical permit for a ductless install, tied to Title 24 (California’s building energy code).
Phone: (408) 733-2000 | Email: info@airandplumbing.com
Whether your home needs a duct-sealing tune-up or a full ductless retrofit, our heat pump and ductless installation team can size the right system for your actual home instead of a one-size-fits-all pitch. Call (408) 733-2000 for a free estimate, or book online in just a few clicks.
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