Furnace Replacement Cost: 80% vs 96% vs Modulating
Furnace replacement typically costs {cost:furnace-replacement:mid}. Here's what 80%, 96%, two-stage and modulating models add, and when they pay off.
A typical furnace replacement costs $6,000, with most jobs falling between $4,700 – $7,800. The type you pick and the venting it needs decide where in that range you land. A basic swap starts at $4,550, and a premium install reaches $9,600. Our figures are before sales tax.
This guide covers the question the main cost guide can't settle: is a high-efficiency furnace worth the premium over a basic 80% unit? You can find the general breakdown in our [furnace replacement cost guide](Furnace replacement).
What each furnace type costs
We calculate these figures from installer labor hours × local rates, plus equipment and materials. We then check them against market prices and real quotes. Here is the full comparison for a typical home:
| Material | Typical | Usual range | Lifespan |
|---|---|---|---|
| Electric furnace | $3,900 | $3,050 – $5,050 | 20-30 years |
| Gas, 80% AFUE, single-stage | $4,900 | $3,800 – $6,350 | 15-20 years |
| Gas, 95-96% AFUE, single-stage | $6,000 | $4,700 – $7,800 | 15-20 years |
| Oil furnace, 85-87% AFUE | $7,000 | $5,450 – $9,100 | 15-20 years |
| Gas, 96% AFUE, two-stage, variable-speed blower | $7,300 | $5,700 – $9,500 | 15-20 years |
| Gas, 97-98% AFUE, modulating | $9,000 | $7,000 – $11,700 | 15-20 years |
As a quick reference, the mid-range total job cost with each common choice:
- Gas, 80% AFUE, single-stage: $4,900
- Gas, 95-96% AFUE, single-stage: $6,000
- Gas, 96% AFUE, two-stage, variable-speed blower: $7,300
- Gas, 97-98% AFUE, modulating: $9,000
The hidden cost: venting
The quoted price is rarely just the furnace, and venting is the item most likely to surprise you.
An 80% furnace is hot enough to vent through a metal flue into your existing chimney or vent. A 95-98% furnace pulls so much heat out of the exhaust that the gases are cool and acidic. They must go out through plastic (PVC) pipe, usually through a side wall, and the condensate needs a drain.
That means a high-efficiency swap often adds:
- New PVC vent and intake pipes through the wall or roof
- A condensate drain line, and sometimes a pump if there's no floor drain nearby
- Possibly a chimney liner if your water heater still vents into the old flue
With new PVC venting, the typical total job comes to $7,200. With a chimney liner added for the water heater, it's $8,000. Reusing existing venting works out at $6,000. Ask every installer to itemize venting separately so you can compare quotes properly.
80% vs 96%: when does the upgrade pay off?
The efficiency rating is the share of the fuel that becomes heat in your home rather than going up the flue. A higher-rated furnace wastes less gas, but the saving depends on how much you heat.
High efficiency tends to pay off when:
- You live in a cold climate and the furnace runs for long stretches
- Gas prices are high where you live
- The furnace is large enough that wasted heat adds up each winter
- Venting is simple, for example a straight run to an exterior wall
- You plan to stay in the home for many years
An 80% unit can make more sense when:
- You use the furnace only lightly, in a mild climate
- Venting a condensing furnace would mean a long or awkward pipe run
- You're selling soon and won't recoup the premium
- Budget is tight and the existing flue is in good shape
We won't quote a payback figure, because it depends on your climate, gas rates and usage. You can estimate it yourself: ask installers for the yearly fuel use of each model, multiply by your local gas rate, and divide the price difference by the yearly saving. Include venting in the price difference.
Single-stage, two-stage or modulating?
Efficiency rating and staging are separate things. A single-stage furnace runs flat out or not at all. A two-stage furnace has a low setting for mild days. A modulating furnace adjusts its output in small steps.
The practical benefits of staging are comfort ones: fewer temperature swings, quieter running, and more even heat from room to room. Variable-speed blowers also circulate air more steadily. If you have hot and cold rooms, or you're sensitive to blower noise, the extra cost for two-stage or modulating can be worth it. If your current heating already feels fine, a single-stage 96% unit gets you most of the efficiency gain for less.
Other costs that move the price
- Ductwork: Sealing and plenum changes, or partial duct replacement, add to the total. A new furnace on leaky ducts wastes some of what you paid for.
- Access: Attic and crawlspace installs take more labor than a basement, garage or closet.
- Size: Make sure the installer sizes the furnace to your home rather than copying the old unit. Oversized models cycle on and off and waste money.
- Permits: Gas and electrical work usually needs a local permit, and the installer should normally handle it.
Incentives
The federal 25C tax credit has ended: it doesn't apply to property placed in service after 31 Dec 2025. Some states run IRA home energy rebate programs, and availability varies. Utilities often offer rebates on efficient equipment, so check the DSIRE database for state and utility incentives before you sign.
Should you consider a heat pump instead?
If you're replacing a furnace and a central air conditioner together, a [ducted heat pump](Heat pump installation) can do both jobs. A [dual-fuel hybrid](Heat pump installation) keeps a gas furnace as backup for the coldest days. If you only need cooling, look at the cost of a [ductless mini-split](Ductless mini-split). And if the water heater shares the old flue, check the [water heater replacement guide](Water heater replacement), because swapping both at once can simplify venting.
Check your quote
Before accepting a bid, run it through our "is my quote fair" quote checker. Get at least three quotes, each listing the furnace model, venting, ductwork and permit costs separately. A quote that lumps them together makes it impossible to see whether you're paying a fair premium for high efficiency.