Quick answer
Choose ductless when you lack ducts, need room-by-room control, or you're cooling an addition or a few problem rooms; choose central AC when you have sound, well-sized ductwork and want whole-home cooling from one hidden system. Seattle's short but hotter-every-year cooling season makes both viable — and because nearly every ductless unit sold here is a heat pump, the ductless quote is often really a heating-and-cooling upgrade in disguise.
- No ducts, or leaky undersized ones? Ductless wins — it skips duct construction entirely and cools (and heats) the rooms you actually use.
- Sound existing ductwork? Central AC — or a ducted heat pump using the same ducts — is usually the cheaper route to whole-home cooling.
- Ductless units double as heat pumps, which unlocks rebates a cooling-only central AC never sees.
- Past three or four ductless heads, a ducted system usually wins on both price and looks — design matters more than brand.
Use this guide when
You're holding both a ductless and a central AC quote for the same comfort problem, you're adding cooling to a Seattle home that never had it, or you're conditioning an addition, ADU, or upstairs bedroom that bakes every July. The right answer depends on your home's bones, not on which system the estimator prefers to sell.
What actually drives the decision
Three things: whether usable ductwork exists (and honestly, whether it's sized and sealed well enough to trust), whether you want one thermostat or room-by-room control, and whether you'd benefit from the heating side of a ductless heat pump — homes on electric baseboard heat almost always do. A load calculation should back either choice.
Compare your options
Ductless wins when
There are no existing ducts, you're replacing electric baseboard or wall heaters, you need to condition specific rooms (bonus room, ADU, home office), or you want independent zone control. Because ductless units are heat pumps, PSE customers replacing electric heat can qualify for utility rebates up to about $1,500, and Seattle City Light offers instant discounts on qualifying heat pump equipment — cooling-only central AC earns neither.
Central AC wins when
Your duct system is sized and sealed, you want the whole house cooled from one outdoor unit with nothing on the walls, and you prefer a single thermostat. If your furnace is also aging, price the ducted heat pump at the same visit — it reuses the same ducts, heats and cools, and opens the door to WA HEAR discounts of up to $8,000 for income-eligible households.
The hybrid answer
Plenty of Seattle homes land on central delivery for the main floors plus one ductless head for the stubborn room the ducts never reached. It costs more than either pure option but solves comfort problems a single system can't — worth pricing when one room drives the whole project.
Key terms and context
This guide is written for heating & air decisions in the Puget Sound. It uses the same terminology you'll hear from inspectors, technicians, and permit offices.
Too many ductless heads
Solving a whole house with five or six heads can cost more than a ducted system, clutter every wall, and leave you maintaining six filters instead of one. Past a point — usually three to four zones — ducted wins on price, looks, and simplicity. If a quote stacks heads room after room, ask for the ducted comparison before signing.
Bolting central AC onto bad ducts
A new central system pushing air through leaky, undersized crawlspace ducts loses a chunk of its capacity before the air reaches a register — you paid for cooling the crawlspace gets. Duct inspection, sealing, and sizing belong in any honest central AC quote; a bid that never mentions the ducts is incomplete.
How we build this guidance
- Both options are sized to your home's calculated load — never by square footage alone.
- We check rebate eligibility (Seattle City Light, PSE, WA HEAR) before recommending equipment, because it changes the honest answer.
- If your ducts aren't worth reusing — or ductless is overkill — we'll say so and show you why.
Methodology: Decision framework from Eco load calculations, duct assessments, and 2026 Washington rebate program rules (Seattle City Light, PSE, WA HEAR). Install ranges align with Eco's published Puget Sound cost guide.
Last updated: 2026-07-05
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Common questions
Can ductless heat too, or is it cooling only?
Nearly every ductless mini-split sold in the Puget Sound is a heat pump, so it heats and cools year-round. That's a real budget factor: a ductless quote replaces your cooling problem AND can replace baseboard heat, while a central AC quote solves cooling only.
How many ductless heads does my house need?
Fewer than most people expect. Open floor plans often do well with one or two well-placed heads rather than one per room — a load calculation and honest airflow assessment decide it. When the design creeps past three or four heads, we price the ducted alternative alongside it, because that's usually the crossover point.
Which is cheaper to install in Seattle?
With sound existing ducts, central is usually cheaper — you're only buying the equipment, not the delivery system. With no ducts, ductless for the key living areas typically beats building ductwork from scratch. Whole-home ductless with many heads is where the price advantage flips back to ducted.
Do any rebates apply to air conditioning?
Cooling-only AC gets little rebate support in Washington — the programs reward heat pumps. Ductless heat pumps replacing electric heat can earn PSE rebates up to about $1,500, Seattle City Light offers instant discounts on qualifying heat pumps, and income-eligible households can access WA HEAR point-of-sale discounts up to $8,000. If rebates matter to your budget, that alone can settle the ductless-vs-AC question.