Quick answer
If you're adding cooling to a Seattle home, choose the heat pump in most cases. A central AC only cools; a heat pump is the same machine with a reversing valve, so it cools identically in July and takes over your heating the rest of the year. The installed premium is modest — and 2026 Washington rebates apply to heat pumps, not straight AC, which often shrinks or erases the difference.
- Mechanically, an AC is a heat pump that only runs one direction — the cooling performance you feel in August is the same either way.
- The heat pump's premium buys a second function: it displaces most or all of your furnace's work at two to four units of heat per unit of electricity.
- WA HEAR (up to $8,000, income-eligible) and PSE rebates ($500–$1,500, plus a possible fuel-switch bonus) apply to heat pumps only — a straight AC earns nothing.
- Smoke season is a cooling argument, too: sealed windows plus a running system and a good filter beat a box fan in an open window every time.
- Either machine needs correctly sized ducts and a Manual J load calculation — cooling exposes duct problems heating hides.
What does each option cost installed in the Seattle area?
A Ballard Craftsman owner adding cooling to a gas-furnace home faces almost this exact quote sheet. The two systems share the outdoor unit, line set, electrical circuit, and most of the labor — what you're really pricing is the reversing valve and controls against a rebate check and years of cheaper heating.
| Option | Typical installed range | What that covers |
|---|---|---|
| Central air conditioner (added to existing furnace) | $9,000–$15,000 | Outdoor condenser, indoor coil on your furnace, line set, and circuit. Cools only; your existing furnace keeps doing 100% of the heating. |
| Cold-climate heat pump system | $12,000–$20,000 | Same cooling hardware plus heating capability — before rebates. Can run alongside your gas furnace (dual fuel) or replace it outright. |
What changes the price
- Rebates flow one way: heat pumps qualify for WA HEAR point-of-sale discounts and PSE utility rebates in 2026; a cooling-only AC qualifies for neither.
- Existing furnace age: pairing a heat pump with a healthy gas furnace (dual fuel) versus replacing everything changes the scope significantly.
- Duct sizing: many Seattle homes have heating-only ducts that are marginal for cooling airflow — an inspection belongs in every bid.
- Electrical: both need a dedicated 240V circuit; panel work, if required, is the same cost either way.
- Permits: mechanical and electrical permits apply to both, and Washington energy code treats the heat pump favorably at inspection time.
Ranges are representative Seattle / Puget Sound installed prices, not a quote — your home's specifics set the real number. Eco gives you an upfront price before any work begins.
How do they work differently?
How a central air conditioner works
Refrigerant absorbs heat from your indoor air at the coil above the furnace, gets compressed, and dumps that heat outside through the condenser. It is strictly a one-way heat conveyor: inside to outside. When October arrives, the machine goes dormant for eight months while your furnace carries the load alone.
How a heat pump works
Identical refrigeration circuit, plus one part — a reversing valve — that lets the heat flow either direction. Summer: it moves indoor heat outside, exactly like the AC. Winter: it runs backward, harvesting heat from outdoor air and delivering two to four units of warmth per unit of electricity. One outdoor unit, twelve months of work instead of four.
Pros and cons, honestly
Heat pump
Pros
- Same summer cooling as an AC, plus efficient heating the other eight months
- Only option of the two with 2026 rebate support in Washington
- Can slash gas or electric heating costs immediately, especially paired with time-of-use awareness
- One system to maintain instead of an AC plus an aging furnace
- Cleanest path if whole-home electrification is anywhere in your plans
Cons
- Higher installed cost before rebates land
- Runs year-round, so it accumulates hours faster than a summer-only AC
- Slightly more complex controls, especially in dual-fuel setups
Central air conditioner
Pros
- Lower sticker price for the cooling-only mission
- Leaves a newer, well-working gas furnace to do what it does well
- Simple, familiar equipment with decades of service history
- Fewer annual run hours can mean a long service life
Cons
- Solves only the summer problem — your heating costs don't change at all
- No Washington rebate support in 2026
- When your furnace eventually dies, you'll buy a second major system anyway
- At resale, an AC-plus-old-furnace combo reads as one more project for the buyer
Which one should you choose?
Choose a heat pump when
Your furnace is past the middle of its life, your summer comfort problem is real, and you'd rather solve heating and cooling in one project. The math is most lopsided for homes heating with electricity or oil, where the heating savings are largest and Seattle-area rebate programs are most generous. It's also the right call if you expect to electrify the house eventually — buying a cooling-only AC now means paying for the same outdoor hardware twice.
Choose a central air conditioner when
Your gas furnace is under roughly eight years old, running flawlessly, and you see no electrification in your future. In that narrow case, the AC's lower price wins the day and the furnace keeps earning its keep. Be honest about the furnace's age, though: if it's within five years of retirement, you're likely buying the outdoor unit twice within a decade.
Also consider: a ductless head for the rooms that actually overheat
If only the upstairs bedrooms or a west-facing living room get uncomfortable, a single-zone ductless system at $5,000–$8,000 installed may solve the real problem for less than either whole-home option. Our ductless vs central AC guide covers that decision in depth.
Ready to compare for your home?
Get honest numbers for both options side by side — an upfront range, the considerations, and the rebates you qualify for, before any work begins.
Continue exploring
- Book: AC installation & replacement →
- Book: Heat pump installation & replacement →
- Compare: Heat Pump vs Electric Furnace: The All-Electric Showdown →
- Compare: Ductless Mini-Split vs Central HVAC: The Whole-Home Decision →
- Compare: Variable-Speed vs Single-Stage HVAC: What the Premium Buys →
- Ductless vs central AC for Seattle →
- What a heat pump costs to run in Seattle →
- How much does an HVAC system cost? →
- All heating & air comparisons →
Common questions
Does a heat pump cool as well as a real air conditioner?
Yes — in cooling mode they are the same machine, and a properly sized heat pump hits the same temperatures and removes the same humidity. There is no cooling penalty for choosing the version that also heats.
Can I keep my gas furnace and still add a heat pump?
Absolutely — that's a dual-fuel setup, where the heat pump handles most days and the furnace takes over in deep cold. It's a popular configuration for Seattle homes with newer furnaces, and switching from gas may qualify for a PSE fuel-switch bonus on top of the standard rebate.
What do the 2026 rebates actually look like for this decision?
For a heat pump: WA HEAR offers up to $8,000 off at point of sale for income-eligible households (≤150% of area median income), and PSE pays $500–$1,500 to electric customers regardless of income. For a cooling-only AC: nothing. The federal 25C tax credit expired December 31, 2025, so these state and utility programs are the whole game now.
Is cooling really necessary in Seattle?
Increasingly, yes. Heat events that were rare a generation ago now arrive most summers, and wildfire smoke weeks make open-window cooling a health tradeoff. A system that lets you close up the house and keep filtering air has become a comfort and air-quality tool, not a luxury.
Last updated: 2026-07-05