Price the swap.
Installed cost to replace a furnace, with or without central AC. Priced by furnace type, efficiency, home size, and install complexity, with the full breakdown shown.
How we calculated this
Furnace size uses a simplified heating load of 45 BTU per square foot, rounded up to standard cabinet sizes (40k to 120k BTU). This approximates an average climate; a real installation should be sized with an ACCA Manual J load calculation, which accounts for insulation, windows, and local design temperature. Oversizing is the most common sizing error and causes short cycling.
Equipment prices reflect typical 2026 contractor-supplied unit costs by furnace type and size. Condensing (95-97% AFUE) furnaces cost more up front and require PVC venting and a condensate drain; 80% AFUE units vent through a metal flue. AFUE ratings and minimum efficiency standards are set by DOE.
Labor covers removal, setting, gas and electrical tie-in, and startup for a one-day swap by a two-person crew. The venting adder covers the PVC vent run and condensate work of an efficiency upgrade; the access adder covers attic or crawlspace installs and plenum or duct modifications.
Permit, inspection, old-unit disposal, and thermostat tie-in are grouped at a flat $550, which matches most jurisdictions. Skipping the permit is not a savings; unpermitted HVAC work surfaces at home sale.
The AC bundle prices a matched condenser and coil sized at roughly 600 square feet per ton, installed in the same visit. New systems use A2L refrigerants (R-454B and R-32) following the 2025 phase-down of R-410A equipment; technicians handling refrigerant must hold EPA Section 608 certification. Bundling shares labor and typically saves $500-1,000 versus separate installs.
What a furnace replacement costs in 2026
A typical gas furnace replacement costs $4,500 to $8,000 installed. Bundle a central AC into the same visit and the project runs $9,000 to $14,000. Electric furnaces come in cheaper, $3,000 to $5,500, because the units are simple. Oil runs highest, $6,000 to $9,500, because the equipment is expensive and fewer techs work on it.
Those are wide ranges, and the spread is not random. It comes from four things: the size of the unit, the efficiency tier you pick, what the install actually involves beyond swapping boxes, and whether the AC rides along. The calculator above prices all four. The rest of this page explains where each dollar goes, so a quote can't hide anything from you.
How we calculated these numbers▾
Sizing uses a simplified 45 BTU per square foot heating load rounded to standard cabinet sizes; a real install should be confirmed with an ACCA Manual J calculation. Equipment and labor figures reflect typical 2026 contractor pricing. Efficiency tiers follow DOE AFUE standards. AC bundle pricing assumes current A2L refrigerant equipment (R-454B/R-32) and EPA Section 608 certified handling.
Region moves the number too. Metro labor rates in the Northeast and West Coast push installed prices 15 to 25 percent over the national middle, while much of the South and Midwest sits under it. Late fall is peak season and prices firm up when the first cold snap fills the schedule; the same replacement quoted in April often comes in a few hundred dollars lighter, and you are not negotiating against a dead furnace.
What actually happens on install day
A straight swap is a one-day job, and knowing the sequence helps you spot a thin quote. The crew shuts gas and power, disconnects the flue, plenum, and gas line, and hauls the old unit out; that is the first hour. Setting the new furnace, adapting the plenum sheet metal to the new cabinet, and reconnecting gas, flue, and low-voltage wiring eats the middle of the day. Startup is the part worth being home for: a combustion check, gas pressure adjustment, temperature rise measured against the data plate, and the thermostat cycled through its stages. Four to eight hours, two techs, heat by dinner.
The add-ons are what stretch it. New PVC venting for a condensing unit means drilling the rim joist and running pipe, half a day. Duct or plenum modifications, a fuel switch, or a furnace living in a crawlspace can push the job to two days. None of that is a problem. All of it should be itemized before the truck shows up, which is exactly what the complexity input above prices.
Repair or replace: the 50 percent rule
Before pricing a new furnace, make sure you need one. The industry shorthand is the 50 percent rule: if the repair costs more than half the price of replacement and the furnace is past 12 years old, put the money toward the new unit. It is a rule of thumb, not physics, but it holds up because an old furnace that just ate a $1,400 control board is still an old furnace. The blower is next. Then the inducer.
One exception in each direction. A cracked heat exchanger ends the discussion regardless of age: it can leak combustion gases into your air, most techs will red-tag the unit on the spot, and at $1,500 to $3,000 the fix costs half a furnace anyway. And in the other direction, cheap sensor-level fixes are worth doing even on a 15 year old unit. A $200 flame sensor buying two more winters is fine math.
Situation | Call | |
|---|---|---|
| Under 10 years old, repair under $1,000 | Any failed component | Repair |
| 12-15 years old, repair under 50% of new | Sensors, switches, ignitor | Repair, start saving |
| 12-15 years old, repair over 50% of new | Blower, control board, gas valve | Replace |
| Any age | Cracked heat exchanger | Replace, no debate |
| Past 15 years, any major repair | Anything over ~$700 | Replace |
The 50 percent rule in table form. The age threshold matters as much as the dollar threshold: half of gas furnaces are done by year 18.
What each component costs to fix
Furnaces fail in predictable order, and the prices are predictable too. Sensors and switches go first and cost the least. Motors and boards go next and cost real money. The heat exchanger goes last and takes the furnace with it.
Parts + labor | What it does when it fails | |
|---|---|---|
| Flame sensor | $150-250 | Furnace lights, then shuts off in seconds |
| Hot surface ignitor | $200-400 | Clicks, hums, never lights |
| Pressure switch | $200-350 | Won't start; error code before ignition |
| Inducer motor | $400-700 | Loud whine or grinding at startup |
| Gas valve | $400-800 | No gas flow; furnace runs cold air |
| Blower motor | $500-1,200 | No airflow, or airflow that never stops |
| Control board | $500-1,200 | Random behavior; the furnace's brain |
| Heat exchanger | $1,500-3,000 | Red tag. Replace the furnace. |
2026 typical prices, parts plus labor. A $95 diagnostic fee usually gets waived if you do the repair with the same company.
Worth knowing before the tech arrives: half of these failures announce themselves the same way, a furnace that tries to start and gives up. The difference is in the error code blinking on the control board behind the lower panel. Count the flashes, look up the code on the door sticker, and you will walk into the repair conversation knowing whether you are buying a $200 sensor or a $900 motor. Techs quote differently to people who counted the flashes.
80% or 96%: the efficiency decision
AFUE is the percentage of fuel that becomes heat in your house instead of going up the flue. An 80% furnace wastes one dollar in five; a 96% condensing furnace wastes four cents. The condensing unit pulls that extra heat out of the exhaust until the water vapor in it literally condenses, which is why it needs a PVC vent out the sidewall and a condensate drain instead of a chimney.
80% AFUE | 96% AFUE | |
|---|---|---|
| Equipment (80k BTU) | $2,600 | $3,800 |
| Venting | Existing metal flue | New PVC + condensate, ~$600-900 |
| Annual gas cost (cold climate, ~$1,000/yr heat) | $1,000 | $835 |
| Payback on the difference | n/a | 7-11 years, faster where winters bite |
The efficiency upgrade is a climate decision. Minnesota pays it back. Georgia mostly doesn't.
The trap in this decision is the orphaned water heater. In many older homes the furnace and water heater share a chimney flue. Pull the furnace off to sidewall PVC and the water heater is suddenly venting alone into a flue sized for two appliances, which drafts poorly and can require a chimney liner at $800 to $1,500. Good installers flag it in the quote. Bad ones let the inspector find it. If your water heater shares the flue, ask about the liner before you sign, not after.
Should the AC go in the same truck
If your air conditioner is past 10 years old, replace it with the furnace. Not because a salesperson said so, but because three things line up. The labor is shared: the crew is already there, the refrigerant lines and plenum are already open, and doing both in one visit typically saves $500 to $1,000 versus separate installs. The coil is matched: your indoor evaporator coil sits on top of the furnace and should be paired to both the new furnace airflow and the new condenser. And the refrigerant era changed: new AC equipment moved to A2L refrigerants (R-454B and R-32) after the R-410A phase-down, so patching an aging R-410A condenser onto a new furnace is spending money on a dead platform.
The counter-case is real too. An AC under 8 years old with no issues is not a bundle candidate; run it out. And if cooling barely matters in your climate, the bundle just inflates the project. The calculator prices both paths, so compare them with your numbers instead of the salesperson's.
A 1,800 square foot two-story in Columbus needs 1,800 × 45 = 81,000 BTU, which rounds to an 80,000 BTU cabinet (Manual J on this house comes in a touch lower; the cabinet size holds). The owners pick a 96% condensing furnace for the Ohio winters: $3,800 equipment, $2,100 labor, $900 for the new PVC venting and condensate pump, $550 permit and disposal. Their AC is six years old, so it stays.
Total: $7,350, right in the middle of the $6,400-8,500 quotes they collected. The 96% unit saves about $165 a year in gas over the 80% option at Columbia Gas rates, paying back the roughly $1,700 efficiency premium in 10 years, with the furnace warrantied for 10 and expected to run 18. The quote also included the chimney liner check: their water heater has its own flue. No liner needed. That question cost nothing to ask.
Composite illustration based on typical project dimensions, regional contractor pricing, and 2026 material costs. Not a specific real project.
Where furnace quotes go wrong
Oversizing is the classic. An installer who sizes the new furnace by copying the old one, or worse by upsizing it "for comfort", is skipping the load calculation. An oversized furnace short cycles: blasts, shuts off, blasts again. It wears components faster, heats unevenly, and costs more up front for the privilege. Insist on a Manual J. If the quote does not mention one, that is your answer about the installer. Cross-check the size yourself with the BTU calculator.
The other patterns are quieter. Quotes that bundle "miscellaneous materials" without itemizing venting. The permit that is not in the quote at all, which means it is not being pulled, which surfaces when you sell the house. And single-quote pricing: furnace installs have per-job spreads of $2,000 between reputable companies in the same city, so a single quote tells you nothing about the market. Three itemized quotes. Same rule as solar, same reason.
Last one, and it deserves its own paragraph: before buying heating capacity, check whether you need less of it. Attic insulation is the cheapest heat you will ever buy, and a house that leaks less can sometimes drop a cabinet size. Price it with the insulation calculator. And if you are replacing both furnace and AC anyway, price a heat pump against the bundle: one system doing both jobs, increasingly viable in cold climates, and sometimes cheaper than furnace plus condenser once state electrification rebates land.
Frequently asked
How much does it cost to replace a furnace in 2026?
A typical gas furnace replacement runs $4,500-8,000 installed: roughly $1,900-4,600 for the unit, $1,800-2,200 in labor, plus permit, disposal, and any venting changes. Electric furnaces run cheaper ($3,000-5,500); oil furnaces higher ($6,000-9,500). Bundling central AC adds $5,000-7,500 but saves shared labor.
Should I repair or replace my furnace?
Use the 50% rule: if a repair costs more than half of replacement and the furnace is past 12 years old, replace it. A cracked heat exchanger always means replacement. Below that line, single-component fixes like a flame sensor ($150-250) or ignitor ($200-400) are worth doing even on older units.
Is a 96% furnace worth it over an 80% furnace?
In cold climates, usually yes: the extra 16 points of efficiency saves roughly 15-20% on gas, which pays back the $1,200-2,000 price difference in 6-10 years, faster where winters are long. In mild climates with short heating seasons, the 80% unit often pencils out better, especially if switching to condensing venting adds cost.
Should I replace the furnace and AC at the same time?
If the AC is over 10 years old, yes. The installs share labor, the new coil is matched to the new furnace, and current AC equipment uses A2L refrigerants (R-454B, R-32) since the R-410A phase-down, so an old condenser paired with a new furnace is a compatibility dead end. Bundling typically saves $500-1,000 versus separate visits.
How long does a furnace replacement take?
A straight swap is one day: 4-8 hours for a two-person crew. Add half a day for new PVC venting on an efficiency upgrade, and a full extra day for duct modifications or a fuel switch. You will be without heat during the work, so winter replacements are usually scheduled as the first job of the morning.
How long should a furnace last?
15-20 years for gas, 20-30 for electric. Annual filter changes and keeping the blower clean do more for lifespan than any service plan. If your furnace is past 15 and needs a major component, put the repair money toward replacement.
Should I consider a heat pump instead of a new furnace?
Worth pricing, especially in mild and moderate climates where modern cold-climate heat pumps handle the full season. You replace furnace and AC with one system, and some states offer electrification rebates. In severe winters, a common setup is a heat pump with the gas furnace kept as backup (dual fuel). Run the heat pump calculator to compare.
Sources
- DOE - Furnaces and Boilers - AFUE definitions, efficiency standards, and replacement guidance
- ENERGY STAR - Furnaces - Certified efficiency tiers used in the 80% vs 96% comparison
- ACCA Manual J - The residential load calculation a proper sizing quote should include
- EPA Section 608 - Refrigerant handling certification governing the AC side of a bundle
- EIA - Heating Fuel Data - Fuel price and consumption data behind the efficiency payback math
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