Furnace Replacement Cost in 2026
A gas furnace costs $3,800 to $12,000 installed in 2026, and most quotes land between $5,200 and $8,800. The single biggest driver inside that range is the efficiency tier you choose, and the second is whether the new furnace needs different venting.
Cost by efficiency tier
| Efficiency | What it means | Installed range |
|---|---|---|
| 80% AFUE | Standard, vents through an existing flue | $3,800–6,200 |
| 90 to 95% AFUE | Condensing, needs PVC venting and a drain | $5,200–8,800 |
| 96% AFUE and above | High efficiency, variable speed | $7,500–12,000 |
Installed prices before any rebate. AFUE is the share of fuel energy that becomes heat in your house.
The venting trap
This is the line item that surprises people. An 80 percent furnace vents hot exhaust up a conventional flue. A condensing furnace above 90 percent extracts so much heat that the exhaust is cool and acidic, so it needs PVC venting through a wall and a condensate drain with somewhere to go.
Moving from 80 to 90 percent therefore is not just a more expensive box. It can mean new vent runs, a condensate pump, and sometimes relining the old chimney because the water heater was sharing it and is now venting alone into an oversized flue. Ask whether any of that is in the quote before you compare two numbers.
Sizing
Furnaces are sized in BTU of input, commonly 40,000 to 120,000 for a house. Output is input multiplied by the AFUE, which is why an 80,000 BTU furnace at 96 percent delivers more usable heat than one at 80 percent.
The correct size comes from a Manual J load calculation, not from square footage and not from matching whatever is currently installed. Replacing like for like perpetuates any error made decades ago, and oversized furnaces short cycle, wear faster and heat unevenly.
What else moves the price
- Fuel type. Gas is the baseline. Electric furnaces cost less to install and usually far more to run. Oil is a different market with its own service considerations.
- Blower type. A variable speed ECM blower costs more and runs quieter and cheaper.
- Access. A basement swap is straightforward. A furnace in a tight attic or a crawl space is not.
- Gas line and electrical work. Frequently quoted separately and not included in our ranges.
- Timing. A December failure costs more than an August replacement, in both price and negotiating position.
Is high efficiency worth it?
It depends on your gas price, your climate and how long you will stay, and the honest answer for a mild climate with cheap gas is often no. The payback comes from the fuel you no longer burn, so the colder your winters and the more expensive your gas, the faster the higher tier repays the difference. Run it with your own bills rather than a national average, using the method on our heat pump comparison page.
Checking your quote
- Confirm the AFUE and the BTU input of the exact model quoted.
- Ask whether venting changes are included, and what they involve.
- Ask what happens to the water heater flue if the furnace is leaving it.
- Confirm permits, removal and disposal are in the price.
- Ask for the load calculation, or how the size was chosen.
Check a quote
Common questions
How long does a furnace last?
Fifteen to twenty years is common, longer than a heat pump because it only works one season a year. Cracked heat exchangers and repeated ignition failures are the usual end of life signals.
Can I just replace the furnace and keep the AC?
Yes, and it is often correct if the air conditioner is young. Confirm the new blower is compatible with the existing coil.
Should I switch to a heat pump instead?
Worth a quote, particularly if the air conditioner is also aging. Our comparison page sets out how to decide on your own utility rates, and cold climate performance covers northern states.
Ranges are triangulated from published 2026 pricing sources and restated to a single scope. Planning ranges, not quotes. Last reviewed July 2026.