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Bellingham Heating & Cooling — Bellingham's Energy Savings Team
Ductless mini split head installed on the wall of a Bellingham living room

Ductless mini split vs. Central ducted heat pump

Ductless mini split vs. central heat pump: which one fits your house?

If you already have good ducts, go ducted. If your house has never had ducts — most pre-1950 Bellingham stock — go ductless. The rebate rules differ, and that matters.

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The short answer

Let the ductwork decide. If the house already has sound, sealed ducts in conditioned space, a ducted heat pump gives you even temperatures and no wall units. If it has never had ducts, as most pre-1950 Bellingham houses have not, ductless is far cheaper than inventing a duct system to justify one.

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Ductless mini split vs. Central ducted heat pump, line by line

Where one option is genuinely better for a Bellingham house, the cell is marked. Where it is a wash, we say so.

What you are comparing Ductless mini split Central ducted heat pump
Cost in a house with no existing ducts You are buying equipment and linesets, not carpentry. Published Bellingham ranges run roughly $3,000 to $10,000 depending on zone count. better Add duct design, soffits or a crawlspace trunk run. In a 1920s house that work can cost more than the heat pump.
Cost in a 1990s house with good ducts already You would be abandoning a duct system you already own and hanging heads on finished walls. Published Bellingham ranges for a ducted air-source heat pump run roughly $4,000 to $8,000, and the ducts are free. better
Even temperature between rooms A head heats the space it can see. Closed bedrooms at the end of a hall stay cooler unless they get their own head. A register in every room, which is why ducted still wins on a floor plan with lots of doors. better
Zoning and part-load control Every head is its own setpoint. Heat the living room and let the spare bedroom drift. better One thermostat for the whole airstream unless you pay for zone dampers.
Duct losses None. There is no duct to leak into a vented Bellingham crawlspace. better Real, and often the largest single loss in an older house where the trunk runs through an unconditioned crawl.
Appearance indoors A visible head high on the wall in each conditioned space, plus a lineset cover outside. Registers and a return grille. Nothing on the wall. better
PSE rebate eligibility Eligible for the $1,500 electric-resistance conversion rebate, but only if fully ductless. Any duct run at all, including a short run from a concealed indoor unit, disqualifies it. Eligible for the same conversion rebate, and the only option eligible for PSE’s heat-pump-to-heat-pump upgrade rebate, which excludes ductless. better
Filtration and fresh air Thin washable filters at each head. Poor platform for a serious wildfire-smoke filter. A central cabinet that will hold a deep pleated or MERV-13 filter, and an easy place to tie in an ERV. better

Rows with no mark are close enough that the difference will not decide your project.

Choose Ductless mini split if

  • The house has no ducts and never has: a 1910 bungalow, a workers’ cottage, a converted attic, an ADU over a garage.
  • You want a specific room fixed — the bonus room that bakes, the addition that never heats — rather than the whole house rebuilt.
  • You are heating and cooling a space with wildly variable use, like a rental unit or a home office you shut down at 5:30.
  • You want the DIY or partial-install path. Kits with professional commissioning exist for ductless; they do not exist for a ducted system.

Choose Central ducted heat pump if

  • You have sound ducts in conditioned space, usually a 1990s or newer house. Reusing them is the cheapest good outcome available.
  • The floor plan is a maze of closed rooms where you would need five or six heads to do what one air handler does.
  • You care about central filtration for wildfire smoke season, or you plan to add an ERV.
  • You already have a heat pump and are upgrading it. PSE’s heat-pump-to-heat-pump rebate is ducted-only, so going ductless would forfeit it.

What changes this answer in Bellingham

Bellingham splits cleanly along its construction eras on this question. The 1890s to 1930s stock was built for stoves and later got baseboard, so there is nothing to duct into and ductless is the obvious answer. The 1950s to 1970s ramblers are the genuinely ambiguous middle: some got ducted electric furnaces worth reusing, many did not. Houses built from the 1990s onward almost always have real ducts, and there the ducted heat pump is both cheaper and better. One rebate trap: PSE’s ductless rules are absolute about fully ductless operation, so the popular compromise of a concealed indoor unit with a short duct run to two bedrooms will pass inspection and still fail the rebate.

Washington's energy code puts Bellingham's outdoor heating design temperature at 19°F, against 24°F at Sea-Tac, in climate zone 4C (marine). We size from a load calculation against that number, not from the square footage of the house.

Money that moves this decision

  • $1,500

    Available now

    $2,400 with PSE Efficiency Boost for income-qualified households.

    Paperwork:
    We file it
    Deadline:
    No published end date — tariffed and subject to change
    Verified:
    2026-09-04 · source

  • $1,500

    Available now

    $2,400 with Efficiency Boost. Ducted systems only — ductless is not eligible.

    Paperwork:
    We file it
    Deadline:
    No published end date — tariffed and subject to change
    Verified:
    2026-09-04 · source

  • Midstream HVAC Equipment Discount

    Puget Sound Energy (with ICF)

    $300–$600

    Available now

    Tier 1 $300 (SEER2 ≥15.2 / HSPF2 ≥8.1, retrofit only) · Tier 2 $400 (SEER2 ≥15.2 / HSPF2 ≥8.5) · Tier 3 $600 (SEER2 ≥16 / HSPF2 ≥9.5).

    Bellingham note: Whether this discount can be combined with the $1,500 conversion rebate is unconfirmed: PSE’s conversion page says its rebate "cannot be combined with any other rebates except where noted", while PSE’s heating hub tells customers to ask their contractor. We quote it separately and confirm with a PSE Energy Advisor before counting it toward your total.

    Paperwork:
    Comes off the equipment price
    Deadline:
    No published end date
    Verified:
    2026-09-04 · source

  • Raises other PSE rebates

    Income-qualified

    Heat pump $1,500 → $2,400 · heat pump water heater $1,000 → $1,100 · smart thermostat $75 → $175.

    Paperwork:
    We file it
    Deadline:
    Ongoing
    Verified:
    2026-09-04 · source

  • Community Energy Challenge — moderate income

    Sustainable Connections + Opportunity Council

    Up to $2,000

    Income-qualified

    For a ductless heat pump upgrade. Weatherization incentives average roughly 45% of project cost. Stated by CEC to be in addition to utility rebates.

    Paperwork:
    The program files it
    Deadline:
    Ongoing
    Verified:
    2026-09-04 · source

Questions Bellingham homeowners actually ask

Can I duct a mini split to two bedrooms and still get the PSE rebate?
No. PSE’s ductless requirement is fully ductless, and it explicitly excludes systems using ducting of any length or size, including short duct runs from concealed indoor units. The install may be perfectly good engineering and still fail the rebate, so decide which you want before ordering equipment.
Are my 1965 crawlspace ducts worth keeping?
Sometimes, and it is worth an hour to find out. We look for crushed flex, disconnected boots, insulation that has fallen off, and whether the trunk is inside or outside the insulation envelope. A leaky duct system in a vented Bellingham crawlspace can throw away a serious fraction of what you paid to heat, and sealing it is cheap compared with replacing it.
How many mini split heads replace one ducted system?
Usually three to five in a typical Bellingham single-family house, depending on how many doors close. A room-by-room load calculation at the 19°F design temperature tells you the count and the capacity; guessing by square footage is how people end up with an oversized head that short-cycles in the shoulder season.
Is a ducted heat pump quieter than mini splits?
Indoors, usually yes, because the air handler is in a crawlspace, garage or closet rather than on the living room wall. Outdoors they are comparable. If indoor noise is your main concern, ducted is the safer bet, and a properly sized variable-speed system running long and low is quieter than an oversized one cycling hard.
Can I mix the two?
Yes, and it is a common Bellingham answer: keep a ducted system for the main floor and add a single ductless head for the finished basement or the addition the ducts never reached. Just know that a mixed system is not a fully ductless system for rebate purposes.

Next steps on this decision

Get this priced both ways

We will quote the option that fits your house and tell you what the other one would have cost, so the comparison is yours to make, not ours.

Or call or text (360) 592-3824. Estimates carry the standard $89.99 trip charge, refunded as company credit when you accept the bid. We do not sell or share your details.

Ready for a straight answer on your house?

Tell us what you have now and what you want it to do. We will tell you what fits, what it costs, and which rebates you actually qualify for — before anyone comes out.

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