Kent and Auburn sit about eight minutes apart on the valley floor, share a lot of the same housing stock, and get quoted wildly different numbers for the same job. We see it constantly: two neighbors on similar 1980s split-levels, one holding a $4,900 proposal and one holding a $9,400 proposal, both for "a new furnace."
Here is what the work actually costs in these two cities in 2026, what moves the price, and the honest part most proposals skip — the cases where replacing the furnace is the wrong purchase entirely.
What a furnace replacement costs here in 2026
Kent and Auburn are both standard markets in our pricing. That means these are the real installed ranges, including equipment, labor, materials, the mechanical permit and the inspection.
| Job | Installed cost | Notes |
|---|---|---|
| JobGas furnace replacement | Installed cost$4,000 – $8,000 | Notes80–92% AFUE at the low end, 96–98% AFUE at the top |
| JobFurnace + central AC together | Installed cost$10,000 – $16,000 | NotesOne crew, one permit, one day in most homes |
| JobAdd AC later to a new furnace | Installed cost$5,000 – $12,000 | NotesSeparate job, separate mobilization |
| JobDucted heat pump instead | Installed cost$12,000 – $18,000 | NotesReplaces heating and cooling in one system |
If your quote falls well under $4,000, ask what is missing. Usually it is the permit, the new venting, or the sheet metal transition at the plenum. If it is well over $8,000 on a standard Kent or Auburn home, ask what is included that a basic swap doesn't need — sometimes there's a real answer, like a full duct modification, and sometimes there isn't.
You can see your own starting numbers in about a minute with our instant estimate tool, or get the full scope on our furnace services page.
Why the same job prices differently in these two cities
Kent: East Hill, West Hill, and the valley floor
Kent's housing is genuinely mixed, and that mix shows up on the invoice. East Hill and West Hill split-levels and ramblers from the 1970s and 1980s almost always have a furnace in a garage or hallway closet with usable ductwork already in place. Those are the clean, fast, low-end-of-the-range jobs.
The complications in Kent are closets. A lot of valley-era homes put the furnace in a tight interior closet sized for a 1980s cabinet. A modern 96% unit is a different shape, vents through PVC instead of the old metal flue, and needs a condensate drain that didn't exist before. That's not an upsell — it's code and physics. Expect it to add real money, and expect an honest contractor to explain why before the proposal lands.
State energy code lists a 21°F winter design temperature for the Kent area, which is what any correct sizing calculation gets run against.
Auburn: Lea Hill, Lakeland Hills, and the older core
Auburn runs warmer. The code design temperature here is 25°F — the mildest in our entire 45-city service area. That matters more than people think, because it means a Kent home and an Auburn home of the same square footage don't necessarily need the same size furnace.
Auburn's newer Lea Hill and Lakeland Hills construction tends to be straightforward: accessible equipment, decent ducts, modern venting already in place. The older housing nearer downtown and the valley core is where we find undersized returns, original 1960s ductwork, and the occasional oversized furnace that was replaced once already with whatever was on the truck that day.
Across both cities, a real load calculation decides the size. Square footage alone doesn't. Oversized furnaces short-cycle, wear out early, and make the house feel drafty even while the gas bill climbs.
The five things that actually move your price
- Efficiency tier. A standard 80–92% AFUE unit is the cheapest route. A 96–98% condensing furnace costs more up front and usually needs new PVC venting and a condensate line. It burns less gas. Whether the payback works depends on how long you're staying.
- Size and home layout. Two-story homes, long duct runs, and finished basements all take more labor than a one-story rambler with the furnace in the garage.
- Venting changes. Switching from an atmospheric flue to a sealed-combustion condensing unit means new vent routing through a wall or roof. This is one of the biggest single line items people don't anticipate.
- Sheet metal and plenum work. New cabinets rarely match old openings. Custom transitions get fabricated, not improvised.
- Gas and electrical. Most swaps reuse existing connections. Some need a gas line adjustment or a dedicated circuit corrected to current code.
The furnace vs. heat pump question, answered honestly
This is the conversation worth having before you spend anything.
A furnace replacement at $4,000 to $8,000 buys you heat. That's it. If your summers in the valley have gotten old — and in Kent and Auburn, they have — adding central AC later costs another $5,000 to $12,000. Add those together and you're past the price of a ducted heat pump at $12,000 to $18,000 that does both jobs from one outdoor unit.
Auburn's 25°F design temperature and Kent's 21°F both sit comfortably inside the range where modern heat pumps deliver full output at high efficiency. This is not a marginal cold-climate gamble. It's one of the best heat pump climates in the country.
When the furnace is still the right call: your gas furnace is young and healthy and just needs a part; you already have working AC you're not ready to replace; your budget this month is $5,000, not $14,000; or you're keeping a rental where the lowest reliable installed cost wins. We say so, and we quote the furnace. Honest beats expensive.
When the heat pump wins: the furnace is 12 or more years old, you want cooling, and a local utility rebate may apply toward the heat pump that would not apply to a furnace. We walk through the full comparison in heat pump vs. gas furnace in Western Washington.
What about rebates and tax credits?
Straight answer: gas furnace replacements generally don't earn utility rebates. Rebate programs in this region target high-efficiency heat pumps, because that's what the utilities are trying to move the market toward.
Kent and Auburn are both billed by one utility for electricity and one for gas, so there's no meter-by-meter boundary to untangle the way there is in Renton or Burien. If you go the heat pump route, local utility rebates may apply; the amount depends on what is being replaced and the equipment installed. Programs change and pay only through their own contractor networks, so we confirm what your utility actually pays before we quote it, then file the paperwork as part of the job.
Also worth stating plainly: the federal 25C tax credit ended December 31, 2025. No 2026 installation qualifies. If a proposal still shows it as a deduction, that proposal is out of date.
Repair or replace?
The rule we use on a service call: if the furnace is under 15 years old and the repair costs less than half of a new system, repair it. Igniters, flame sensors, and control components are bounded, sensible repairs on an otherwise healthy unit.
The repairs that change the answer are a failed heat exchanger — which is a safety shutdown, not a routine fix — a failing inducer plus blower in the same season, or a third repair across two winters. At that point you're renting time on equipment with no warranty behind it.
Every Varsity installation carries a 10-year parts and labor warranty. That's part of what you're actually buying when you replace instead of patch.
How we quote it
A technician comes out, measures the home, runs the load calculation, looks at the ducts and the venting, and writes you a proposal with Good, Better and Best options on it. You get a written number before anything is ordered. Most Kent and Auburn installs are finished in one day, with warranties registered and the permit inspection scheduled before we leave.
We're based on S 344th St in Federal Way — fifteen minutes from either city, which is why our trucks are in the valley most days.
Book a free in-home estimate or call (253) 785-4622, Monday through Friday, 8 to 6. Owner-operated, licensed VARSIHC766RJ, and we answer the phone after the check clears.