Replacing a furnace averages about $4,771, with most homeowners paying between $2,825 and $6,846 installed. Fuel type sets the floor: electric runs $2,000 to $7,000, natural gas $3,800 to $10,000, and oil $6,750 to $10,000. Higher-efficiency units and tricky venting push you toward the top of each range.
That spread is wide because a furnace price tag bundles four things: the unit, its efficiency tier, the venting and ductwork it needs, and your local labor. Two homes on the same street can pay $3,000 apart for the same heat output. Below is what drives the number, plus a plain decision framework for whether you should replace at all or keep repairing.
Furnace replacement cost by fuel and efficiency
Fuel type is the biggest single factor, so start there. Then efficiency, measured as AFUE (Annual Fuel Utilization Efficiency), decides how much you pay upfront versus how much you burn every winter. A 96% AFUE unit converts 96 cents of every fuel dollar into heat; an 80% unit wastes 20 cents up the flue.
| Furnace type | Typical installed cost | Notes |
|---|---|---|
| Electric | $2,000 to $7,000 | Lowest install cost; higher running cost in cold climates |
| Natural gas | $3,800 to $10,000 | Most common; cost swings with AFUE tier and venting |
| Oil | $6,750 to $10,000 | Higher equipment cost; common in older Northeast homes |
| All types (average) | About $4,771 | Typical range $2,825 to $6,846 |
Efficiency tier layers on top of fuel. A mid-efficiency gas furnace (around 80% AFUE) costs less to buy but more to run. A high-efficiency unit (90%+ AFUE) costs more upfront and lowers your bills, but it vents differently.
| Efficiency tier | AFUE range | Upfront vs. running cost |
|---|---|---|
| Standard | 80% to 83% | Lower price, higher fuel use, vents through a metal flue |
| High-efficiency | 90% to 98% | Higher price, lower fuel use, needs PVC condensate venting |
Why the same furnace costs different amounts
Beyond fuel and AFUE, four things move your quote:
- Size (BTU). A furnace sized to your square footage and climate. Oversizing wastes money and short-cycles the unit; undersizing leaves rooms cold.
- Venting. High-efficiency units produce condensate and need PVC venting plus a drain. In an older home built for a metal flue, that rework can add real labor.
- Ductwork. Leaky, undersized, or missing ducts may need sealing or replacement before a new furnace performs as rated.
- Labor and region. Local rates, permits, and how hard your old unit is to remove all factor in.
Repair or replace: a simple decision framework
The cost calculators bury this part, but it is the real question you came here to answer. Walk these three checks in order.
1. Is it a safety issue? A cracked heat exchanger leaks carbon monoxide. That is a replace, not a patch, full stop. Any safety fault inside the cabinet means the unit comes out.
2. How old is it? Furnaces last about 15 to 20 years, longer with steady maintenance. Under 10 years with one failed part, repair is usually the call. Past 15, start pricing replacement even if it is still limping along.
3. What does the math say? A common industry rule of thumb (not a hard rule): multiply the furnace's age by the repair quote. If the result tops $5,000, lean toward replacing. A 16-year-old unit with a $400 repair is $6,400 on that math, so you would put that money toward a new system instead.
Watch for the signals that stack up alongside age: rising heating bills, uneven heat from room to room, short cycling (the furnace turning on and off in quick bursts), new rattles or booms, and visible rust. One of these is a service call. Three or four on a 15-year-old unit is the system telling you it is done.
The maintenance that delays this cost
The cheapest furnace is the one you do not replace yet. Two habits stretch a unit toward the far end of its 15-to-20-year life and keep efficiency from sliding:
First, change the filter on schedule. A clogged filter starves the blower, makes the furnace work harder, and is a leading cause of premature breakdowns. Most homes need a fresh filter every one to three months; see how often to change your HVAC filter and, if you are not sure what you are buying, furnace filter vs. HVAC filter.
Second, book a yearly professional inspection. A tech catches a hairline heat-exchanger crack, a failing igniter, or a drifting gas valve before it becomes an emergency or a safety hazard. That is also your early warning that replacement is coming, so you can plan instead of buying in a January panic. See how often to have your furnace inspected.
One safety line to hold: DIY stops at the filter and keeping the area around the unit clear. The heat exchanger, burners, gas valve, ignition, and anything else inside the cabinet are for a licensed HVAC pro only.
Common questions
How long should a furnace last before I replace it?
About 15 to 20 years, sometimes longer with regular maintenance. Around the 15-year mark, start getting replacement quotes so a sudden failure does not force a rushed decision in the middle of winter.
Is a high-efficiency furnace worth the extra cost?
It depends on your climate and how long you will stay. In a cold region with a long heating season, the lower fuel use from a 90%+ AFUE unit can pay back the higher upfront price over time. In a mild climate or short stay, a standard-efficiency unit often makes more sense. Factor in that high-efficiency models need PVC venting, which adds cost in older homes.
Can I just keep repairing my old furnace?
Up to a point. If it is under 10 years old and the repair is minor, repairing is usually right. Once it is past 15 with frequent or rising repair bills, or if the repair involves a safety part like the heat exchanger, replacement is the smarter spend.
What is the difference between furnace and AC replacement cost?
They are separate systems with separate price tags, though many homeowners replace both at once to save on labor. For central air pricing, see our guide to the cost to replace an AC unit.
Good maintenance rhythm
- Monthly: Check the furnace filter and replace it when it looks gray or clogged; most homes land on every one to three months.
- Yearly: Book a professional inspection before heating season so a pro can check the heat exchanger, burners, and ignition.
- Ongoing: Keep the area around the furnace clear, listen for new noises or short cycling, and start pricing replacement once the unit passes 15 years.