Quick answer
They're both the indoor box that moves air through your ducts — the difference is how the heat gets made. A furnace burns gas to create heat; an air handler creates none, instead moving air across a heat pump's indoor coil, often with electric strip backup tucked inside. Read your quote carefully: a 'heat pump system' price should include the air handler, while 'dual fuel' means a heat pump paired with a furnace.
- Same job, different heat source: both boxes contain a blower and connect to your ducts — a furnace adds burners and a heat exchanger, an air handler adds a refrigerant coil.
- An air handler is a heat pump's indoor half. On its own it makes no heat (unless its optional electric strips fire).
- Strip heat matters: those backup elements are pure resistance heat at 1:1 efficiency — fine for rare cold snaps, expensive if they run all winter due to a sizing mistake.
- A furnace can partner with a heat pump too — that pairing is called dual fuel, with the furnace as cold-weather backup.
- On quotes: heat pump + air handler is priced as one system ($12,000–$20,000 installed); a standalone air handler swap alone runs roughly $4,000–$8,000 as an estimate.
What does each option cost installed in the Seattle area?
This page is mostly about vocabulary, but the vocabulary carries real dollars. The key reading skill: figure out whether your bid replaces the indoor box, the outdoor unit, or both — apples-to-apples comparisons fail most often right here.
| Option | Typical installed range | What that covers |
|---|---|---|
| Air handler (standalone swap, heat pump already in place) | ~$4,000–$8,000 (estimate) | Replacing just the indoor unit — coil, blower, optional strip heat — matched to an existing or planned outdoor heat pump. |
| Heat pump + air handler (complete system) | $12,000–$20,000 | The full electric pairing, priced as one system. This is the number most 'heat pump quotes' should contain. |
| Furnace replacement | $9,000–$15,000 | Gas furnace on existing ducts and venting. Add an outdoor heat pump later and the same furnace becomes the backup half of a dual-fuel system. |
What changes the price
- Matching: an air handler's coil must be matched to its outdoor heat pump — mismatched pairings quietly sacrifice the efficiency you paid for.
- Strip heat sizing: backup elements sized for genuine emergencies keep bills sane; oversized strips that engage casually turn a heat pump home into a resistance-heat home.
- Rebates: complete heat pump systems (including the air handler) can qualify for WA HEAR up to $8,000 (income-eligible) and PSE rebates of $500–$1,500; a gas furnace qualifies for nothing in 2026.
- Electrical: air handlers with strip heat pull serious amperage — panel capacity gets verified up front, and HEAR can help fund panel work up to $4,000 where needed.
- Permits and code: both installs need mechanical permits; gas furnaces add gas-piping and venting inspections, air handlers add electrical inspection for the strip circuit.
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 furnace works
Gas burns inside a heat exchanger — a sealed metal barrier — and the blower pushes household air across its hot outer surface into the ducts. Combustion byproducts never touch your air; they exit through the flue. The heat is generated on the spot, in the box, every time the burners light. That's why a furnace works alone: it's a complete heating appliance.
How an air handler works
No burners, no flue, no heat of its own. Its blower moves household air across a refrigerant coil, and the outdoor heat pump decides what that coil does — hot coil in winter, cold coil in summer. Most air handlers also carry electric strip elements as backup: pure resistance heat that fires only when the heat pump needs help. Think of it as the delivery half of a two-part machine.
Pros and cons, honestly
Air handler (with heat pump)
Pros
- Completes an all-electric system — no combustion, flue, or carbon monoxide pathway in the house
- Delivers both heating and cooling through one indoor unit
- Built-in strip heat provides automatic emergency backup
- The system it belongs to is the one with 2026 Washington rebate support
- Typically compact and flexible about mounting orientation
Cons
- Useless without its outdoor heat pump — it is half of a system, not a heater
- Strip heat is a silent budget threat if sizing or controls let it run too often
- Heavy electrical draw when strips engage; panel capacity must be verified
Furnace
Pros
- Complete standalone heating appliance — works with no outdoor equipment at all
- High heat output that's independent of outdoor temperature
- Can double as the backup half of a dual-fuel system later
- Familiar technology every HVAC technician can service
Cons
- Heating only — cooling requires adding a separate AC or heat pump coil
- Combustion means venting requirements, gas piping, and CO detectors as code obligations
- No Washington rebate support in 2026
- Ties the home to a gas meter if electrification is in your future
Which one should you choose?
Choose an air handler when
You're installing or already own a heat pump — the air handler is simply its indoor partner, and the two are engineered as a set. It's the automatic answer in all-electric projects: a West Seattle homeowner leaving gas behind, or a Lynnwood split-level replacing an electric furnace, gets an air handler by definition. The decisions worth sweating are the details: coil match, strip-heat sizing, and whether your panel carries the backup load.
Choose a furnace when
You're staying with gas heat, either alone or as the backup half of a dual-fuel pairing. A furnace is also the pragmatic like-for-like swap when the budget only covers the indoor box this year — you can add an outdoor heat pump later and convert the setup to dual fuel without redoing the indoor work, if the furnace is spec'd for it up front. Tell your installer that's the plan so the coil and controls are chosen accordingly.
Also consider: neither box
Ductless mini-splits skip the central indoor unit entirely — each room's head is its own delivery point. If your ducts are poor or nonexistent, the air-handler-vs-furnace question may be the wrong question altogether; see our ductless vs central comparison.
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: Heating installation & replacement →
- Book: Heat pump installation & replacement →
- Compare: Heat Pump With Backup Heat vs Furnace: Does Seattle Need Dual Fuel? →
- Compare: Heat Pump vs Electric Furnace: The All-Electric Showdown →
- Compare: High-Efficiency vs Standard Furnace: Is 95%+ Worth It Here? →
- How much does an HVAC system cost? →
- Heat pump vs gas furnace in the Puget Sound →
- All heating & air comparisons →
Common questions
My quote says 'heat pump with air handler.' Is that one price or two machines?
Two machines, one system, and it should be one price — outdoor heat pump plus matched indoor air handler, typically $12,000–$20,000 installed in the Seattle area. If a bid lists the heat pump alone, ask what indoor unit it pairs with; the answer changes both the price and the performance.
What is strip heat, and should I worry about it?
Strip heat is a set of electric resistance elements inside the air handler that back up the heat pump — the same 1:1 physics as a toaster. It's exactly right for rare cold snaps and defrost support. It becomes a problem only when poor sizing or thermostat settings let it carry load the heat pump should handle; that's the first thing we check when a heat pump home reports a shocking winter bill.
Can a furnace and a heat pump really share one system?
Yes — that's dual fuel: the heat pump's coil sits on the furnace, the heat pump covers the vast majority of hours, and the furnace fires in deep cold. It suits homes with newer furnaces and owners who want gas as a safety net. The controls decide which heat source runs, based on a changeover point set during commissioning.
Why does an air handler cost that much if it doesn't make heat?
The $4,000–$8,000 standalone estimate covers a matched refrigerant coil, a quality blower (often variable-speed), strip-heat hardware and its dedicated circuit, plus transition work to your ducts and the refrigerant connections. It's the delivery half of the system's performance — skimping here throttles whatever outdoor unit you bought.
Last updated: 2026-07-05