Ductless or ducted: which retrofit fits your house?
This is the retrofit decision framework — not the side-by-side hardware table on our compare page. The fork is really about your ducts: homes with sound (or repairable) ductwork usually do best reusing it with a ducted heat pump; homes without ducts — or with ducts not worth saving — usually do best going ductless. Building new ductwork into a finished house is the expensive third path that rarely wins. Add Seattle inputs: pre-war housing stock, panel capacity for ducted vs ductless electrical draw, SCL vs PSE rebate mechanics, and how long you'll stay once you've paid for distribution.
The quick answer
- Have decent ducts? Ducted reuse is usually cheapest per room served
- No ducts (pre-war, baseboard, wall heaters)? Ductless skips a $5,000–$15,000 duct problem
- Duct condition is testable — leakage around 15% is the WA code action threshold
- Aesthetics honesty: ducted is invisible; heads are visible. Decide how much that matters
The case for ducted (when ducts exist)
One indoor unit serves every room through registers you already own, nothing visible changes in the rooms, and filtration/IAQ upgrades (media cabinets, UV) mount centrally. If a duct test shows the system is tight — or sealable — the incremental cost of conditioning every room is low: the distribution is already bought.
The prerequisite is honesty about the ducts: 50-year-old, crushed, or 20–30%-leaky ductwork hands its problems to any equipment attached. Test, then seal (our sheet metal shop rebuilds runs when needed), then size — in that order.
Eastside and North Seattle tract homes from the 1980s–2000s often land here: decent metal trunks, accessible crawlspaces, and owners planning to stay long enough for whole-home comfort to matter. SCL customers with existing gas furnaces frequently price dual-fuel or full heat-pump replacement in the same duct footprint — PSE customers file conversion rebates after install when gas heat is displaced.
The case for ductless
No ducts to inherit means no duct losses, no crawl-space surgery, and installation measured in days: heads where the load is, line sets through 3-inch penetrations. Zoning comes free — each head is its own thermostat, which suits how households actually occupy rooms. For pre-war Seattle stock, baseboard homes, and townhomes, this is the standard path for good reason.
It's also the incremental path: start with the rooms that hurt (bonus room, upstairs bedrooms), extend later. Ducted retrofits don't do 'partial' gracefully.
Owners comparing SCL instant discounts vs PSE conversion rebates should pick configuration first — ductless models often post the highest HSPF2 tiers on program lists, but a ducted reuse on tight ducts still beats four heads you don't need.
The third path: compact ducted hybrids
Slim-duct cassettes — mini-split indoor units feeding short concealed duct runs — split the difference for clusters of small rooms: one hidden unit in a closet or attic serves two or three bedrooms through small grilles. Equipment like the Daikin FIT line extends the same idea at whole-home scale. Worth knowing before assuming the choice is binary.
Hybrid layouts shine in Seattle four-bedroom ramblers where open living areas want one head but bedrooms need doors closed — fewer visible heads, better load match than head-count maximalism.
What does it cost in the Seattle area?
Sourced Seattle-area ranges for the paths:
Ducted heat pump installation
$8,000 – $16,000 typical ~$10,200
All-electric heating + cooling using your existing ductwork
Sources: HVAC Project Cost — Seattle, WA (citing Angi 2026) (2026) · WattFax — 113 WA homeowner quotes (2026)
Ductless mini-split (single zone)
$3,500 – $6,000
One outdoor unit + one indoor head — equipment, labor, electrical, permit
Sources: Seattle Mini Split Pros cost guide (2026) · Angi — ductless mini-split cost, Seattle WA (2026)
Ductless mini-split (multi-zone)
$6,000 – $15,000
One or more outdoor units serving 2–4+ rooms
Sources: Seattle Mini Split Pros cost guide (2026) · Angi — ductless mini-split cost, Seattle WA (2026)
- Ducted range assumes usable ducts — add sealing/repairs where the test says so
- Ductless pricing scales with zone count and line-set routing
- Building NEW ducts into a finished home typically adds $5,000–$15,000 (regional installer figures) — the option that makes the other two look good
- Utility rebates apply to qualifying heat pumps on either path
These are typical Seattle-area market ranges compiled from published cost guides (Angi, HomeGuide, and Seattle-area 2025–2026 cost studies) — market context, not a quote from Glendale Heating & Air Conditioning. Your home's size, equipment, ductwork, electrical, and permits change the number. National figures are marked; Seattle-area labor typically runs above national averages.
The honest trade-offs
Ducted heat pump (reuse ducts)
- Every room served, nothing visible
- Central filtration/IAQ mounting point
- Lowest cost per room when ducts are sound
- Inherits duct condition — test first
- One zone unless dampers added
- Needs mechanical space for the air handler
Ductless mini-splits
- No ducts needed or lost energy through them
- Per-room zoning by default
- Fast, low-demolition install; incremental-friendly
- Heads are visible in rooms
- Per-head filtration is basic — no central media cabinet
- Many zones can out-price ducted reuse
Where retrofits disappoint
Attaching new equipment to untested old ducts — the new system faithfully reproduces the old comfort problems, now with a warranty argument. Skipping the duct test to save a step is the falsest economy in the trade.
On the ductless side: head-count maximalism (a head in every room regardless of load — see the multi-zone guide) and aesthetic surprise (nobody told the owner what a head looks like until install day). Both are design-conversation failures, not equipment failures.
Seattle-specific disappointments: forcing ducted reuse in pre-war homes with 40-year-old flex in unconditioned crawlspaces; or ductless on a tight Queen Anne lot without a noise conversation when the outdoor unit sits under a bedroom window. SCL vs PSE doesn't change the duct question, but it changes which efficiency tier earns rebates once you've picked the path — model numbers belong in the bid, not hand-waved.
Stay-horizon traps: building new ducts into a finished Craftsman you'll sell in three years; or going ductless whole-home when sound ducts and a decade of ownership would have made ducted reuse cheaper per room. This framework walks the fork — the comparison table quantifies ranges after you've chosen a path.
Questions Seattle homeowners ask
How do I know if my ducts are worth reusing?
A duct-pressure test quantifies leakage (WA code treats ~15% as the action threshold at replacement), and a visual crawl assesses routing, crushing, and insulation. Sound ducts are an asset worth thousands; bad ducts are a liability that sealing sometimes rescues. Measure before deciding — we do.
Is ductless cheaper than ducted?
Per the sourced ranges: a single zone ($3,500–$6,000) is far cheaper than a ducted system; a 4-zone whole-home ductless ($10,000–$15,000) overlaps the ducted range ($8,000–$16,000). With sound existing ducts, ducted reuse usually wins whole-home economics; without ducts, ductless wins by not buying a duct system.
Can I mix: ducted downstairs, ductless upstairs?
Yes — hybrid layouts are common and often optimal in Seattle two-stories and expanded homes: the ducted system carries the original footprint, heads serve the addition or the stratified upstairs. It's a load-map decision; the estimate draws it.
Which path do rebates favor?
Neither inherently — SCL and PSE qualify by equipment efficiency, and both ducted and ductless heat pumps populate the lists (ductless models often post the highest HSPF2 numbers, e.g. PSE's ductless threshold is ≥9.5 for gas conversions). The configuration should follow your house; the rebate follows the model number. PSE conversion rebates require network-qualified installers from April 2026 — verify that line in the bid, not on a comparison table row.
Continue exploring
How we know this
Duct thresholds per WA State Energy Code practice; retrofit-cost context from regional installer published figures; path economics from Glendale retrofit work across Greater Seattle housing stock since 1938.
Reviewed by the Glendale Heating & Air Conditioning team · Last updated 2026-07-15
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