Federal Way is home base for us. The office is on S 344th St, and a good share of the furnaces we replace are within fifteen minutes of it — Twin Lakes, Steel Lake, Lakota, Mirror Lake, Dash Point, Redondo, the neighborhoods off S 320th. So when somebody asks what a furnace costs here, we are not guessing off a national average. We are quoting the same housing stock week after week.
Here are the real 2026 numbers, what actually moves them, and the one comparison worth running before you commit.
The short answer
A gas furnace replacement in Federal Way runs $4,000 to $8,000 installed for most homes. Larger homes, or jobs that step up to a high-efficiency condensing furnace with new PVC venting, run $5,000 to $10,000.
That price is the whole job: equipment, labor, materials, permit, hauling the old unit away, and a 10-year parts and labor warranty. Not a box price with line items bolted on later.
Two other numbers belong on the same page, because they change the decision for a lot of people:
- Furnace and central AC replaced together: $10,000 to $16,000
- Ducted heat pump, heating and cooling in one system: $12,000 to $18,000
Federal Way furnace cost by home size
| Home | Typical here | Where the price lands |
|---|---|---|
| HomeUnder 1,400 sq ft | Typical hereSmall rambler, older Mirror Lake or Steel Lake cottage, townhome | Where the price landsLow end of the $4,000–$8,000 range |
| Home1,400–2,000 sq ft | Typical hereThe classic 1970s–80s Federal Way rambler or split-level | Where the price landsMiddle of the range |
| Home2,000–2,800 sq ft | Typical hereTwo-story, larger split-level, updated Twin Lakes home | Where the price landsUpper end of the range |
| Home2,800+ sq ft or high-efficiency | Typical hereLarger newer construction, 96%+ AFUE with new venting | Where the price lands$5,000 to $10,000 |
Use that as orientation, not as a quote. Square footage alone does not size a furnace — a 1,900 square foot split-level with single-pane windows and an uninsulated crawlspace can need more output than a 2,300 square foot 1998 build. That is why a load calculation comes before a model number, not after.
What actually moves the number
Heating load, not floor area
We run the load against Federal Way's winter design temperature, which Washington's energy code puts at 24°F. That is mild — twenty-four degrees is warmer than Puyallup, Sumner or Olympia get designed for. A mild design temperature means the correctly sized furnace here is usually smaller than homeowners assume, and smaller equipment costs less. Oversizing a furnace does not buy comfort. It buys short cycling, temperature swings and a shorter blower life.
Efficiency tier
An 80% AFUE furnace vents through the existing metal flue. A 96% condensing furnace vents through PVC out a sidewall and needs a condensate drain. The equipment costs more and the install work is genuinely different, which is why the same house can land $1,500 or more apart depending on which tier you pick. In our climate, with our gas rates, neither one is automatically the right call — we price both and let you see the payback.
The install details nobody quotes over the phone
- Undersized or crushed return air, which is common in 1970s garages where the furnace shares space with a water heater
- Gas line sizing when a larger appliance load gets added
- Electrical, disconnect, or a dedicated circuit that was never right to begin with
- Condensate routing and drainage for high-efficiency units
- Ductwork that has been repaired with tape for thirty years and is now the actual comfort problem
Federal Way's housing stock works in your favor
Most of this city was built between the 1970s and the 1990s — ramblers and split-levels with a furnace in the garage or a hall closet and existing ductwork already in place. That is the easiest install profile in our entire service area. The duct runs are usually short, the equipment is usually accessible, and crews are not fighting a 1920s balloon-framed house with no return path.
The exceptions worth naming: Dash Point and Redondo waterfront homes deal with salt air, which matters more for outdoor equipment than for a furnace but changes how we spec an AC or heat pump condenser. And any home where the ducts were undersized for the original furnace will stay uncomfortable no matter what new box goes in — that is a ductwork conversation, typically $3,000 to $8,000, and we will tell you if that is where your money actually belongs.
Price the heat pump before you sign
Here is the part most furnace quotes leave out. Federal Way is billed by a single utility for both gas and electric, so there is no meter-by-meter boundary to check the way there is in Renton or Burien. What there is, however, is this: local utility rebate money goes toward qualifying heat pump installations, not gas furnace replacements.
The amount depends on what is being replaced and the efficiency of the equipment installed. Programs change, and they pay only through their own contractor networks — so we confirm what your utility currently pays before we quote it, and we file the paperwork as part of the job. We do not quote a rebate figure we have not verified for your address.
That matters because the gap between paths is smaller than it looks:
- Furnace only: $4,000–$8,000, heating only, no rebate
- Furnace plus new AC: $10,000–$16,000, two pieces of equipment
- Ducted heat pump: $12,000–$18,000, one system, heating and cooling, rebate-eligible
If you already want air conditioning, the furnace-only column stops being a fair comparison. We walk through the full trade-off in heat pump vs. gas furnace in Western Washington, including the cases where keeping gas is genuinely the better answer — a young healthy furnace, or a home where a hybrid setup makes more sense.
And to close the loop on the question we get weekly: the federal 25C tax credit ended December 31, 2025. No 2026 install qualifies. Any quote leaning on it is out of date.
When repair still beats replacement
We would rather say this than sell you a furnace you do not need yet. If your furnace is under 15 years old and the repair costs less than half of a new system, repair it. An ignitor, a flame sensor, a pressure switch — those are maintenance, not a verdict. Replacement becomes the better buy when repairs repeat, when the heat exchanger shows rust or cracking, or when you want cooling anyway.
Getting a real number
Run the instant estimate tool if you want Good, Better and Best starting prices in about a minute — seven questions about the home, no waiting. When you are ready for the exact figure, request a free in-home estimate or call (253) 785-4622, Monday through Friday, 8 to 6.
A technician measures the home, runs the load, checks the duct and venting condition, and leaves you a written proposal with three tiers and no mystery line items. Most furnace replacements are finished in one day, permit pulled and inspection scheduled, with 10-year parts and labor behind it.
We are the company based here. We answer the phone after the check clears.