A Lennox furnace costs $3,000 to $9,500 installed in 2026, with the series and the AFUE rating driving most of that spread and BTU size driving the rest. A Merit 80% AFUE unit sits at the bottom, an Elite 96% AFUE furnace runs roughly $4,800 to $6,700, and the Signature SLP99V at 99 AFUE reaches the top. The most common project, an 80,000 BTU Elite 96% AFUE furnace swapped into existing ductwork, lands between $5,000 and $6,300.
TL;DR: Lennox furnaces run $3,000 to $9,500 installed. Merit is $3,000 to $4,800, Elite is $4,000 to $7,000, and the Dave Lennox Signature Collection is $5,800 to $9,500. The SLP99V is the efficiency flagship at up to 99.0 AFUE, the highest residential rating any major brand publishes. Registered Elite and Signature furnaces carry a limited lifetime heat exchanger warranty on 90+ AFUE models, while 80% AFUE models get 20 years. The federal 25C tax credit expired for equipment placed in service after December 31, 2025, and the current Lennox rebate of up to $1,550 requires a full system, so a furnace-only replacement does not qualify. Get a personalized range from our free HVAC cost estimator.
How Much Does a Lennox Furnace Cost Installed?
Lennox furnace replacement costs $3,000 to $9,500 installed in 2026. The biggest single variable is the series, because Lennox builds three lines that differ in how the burner fires and how the blower moves air, not just in trim level. The table below shows installed ranges for a straight furnace swap on existing ductwork and venting.
| Series | Burner Staging | AFUE Range | Heat Exchanger Warranty | Installed Cost |
|---|---|---|---|---|
| Merit | Single-stage, one two-stage model | 80–96 | 20 years | $3,000–$4,800 |
| Elite | Single-stage or two-stage | 80–97 | Lifetime on 90+ AFUE, 20 years on 80% | $4,000–$7,000 |
| Signature | Two-stage or variable-capacity | 80–99 | Lifetime on 90+ AFUE, 20 years on 80% | $5,800–$9,500 |
Those figures include the furnace, standard labor, a new flue connection to existing venting, a basic thermostat, gas and electrical reconnection at the unit, and startup with a combustion check. They exclude several things that appear on real proposals and can move the total by thousands.
- Ductwork modification or replacement: add $2,000 to $5,000 if the existing trunk and returns are undersized for the new blower.
- Venting conversion: moving from an 80% AFUE furnace to a 90+ AFUE condensing model requires new PVC intake and exhaust plus a condensate drain, commonly $600 to $1,800.
- Chimney liner: if the furnace shared a masonry chimney with a gas water heater and you take the furnace off it, the water heater usually needs a liner, $800 to $2,500.
- Permits and inspection: commonly $150 to $500 depending on the jurisdiction, and gas appliance permits are enforced more consistently than AC permits.
- Electrical and gas line work: a dedicated circuit or an upsized gas line for a larger input rating can add $300 to $1,200.
What Does a Lennox Furnace Cost by BTU Size?
Furnaces are sized by heating input in BTU per hour, not by tonnage, and the price step between sizes is smaller than most homeowners expect. Across the Lennox lineup each 20,000 BTU step adds roughly $400 in the Merit line, $700 in the Elite line, and $900 in the Signature line. The columns below show a Merit single-stage unit, a mid-range Elite unit, and a Signature unit at the same input rating.
| Furnace Input | Typical Home Size | Merit (Low) | Elite (Mid) | Signature (High) |
|---|---|---|---|---|
| 40,000 BTU | Up to 1,000 sq ft | $3,000 | $4,000 | $5,800 |
| 60,000 BTU | 1,000–1,500 sq ft | $3,400 | $4,700 | $6,700 |
| 80,000 BTU | 1,500–2,000 sq ft | $3,800 | $5,400 | $7,600 |
| 100,000 BTU | 2,000–2,600 sq ft | $4,300 | $6,200 | $8,500 |
| 120,000 BTU | 2,600–3,200 sq ft | $4,800 | $7,000 | $9,500 |
Read the square footage column as orientation only. Climate zone matters far more for a furnace than it does for an air conditioner, because a 2,000 square foot house in Minnesota and the same house in Georgia need very different input ratings. Insulation levels, air sealing, window area, and ceiling height change the answer again. A proper Manual J load calculation is the only defensible basis for the number on your quote.
Oversizing is the most common sizing error in furnace replacement, and it is usually free to the contractor and expensive to you. Because the price step between sizes is only a few hundred dollars, a contractor who wants to avoid a callback will simply match or exceed whatever was there before. An oversized furnace short-cycles, heats the house in uneven bursts, wears the igniter and inducer faster, and never reaches its rated efficiency. Ask what input rating the load calculation produced and compare it against what is being quoted.
Lennox Furnace Models — Merit, Elite, and Signature Compared
Lennox lists 17 furnace models in its current residential catalog. Unlike the air conditioner and heat pump lines, the furnace model names did not change during the refrigerant transition, so an older article quoting an ML180E or an SLP99V is still naming current equipment. What did change is the model suffix, which is covered below the table. All specifications here come from lennox.com and were verified August 1, 2026.
| Model | Series | AFUE | Staging | Blower Motor | Availability | Installed Cost |
|---|---|---|---|---|---|---|
| ML180E | Merit | up to 80.0 | Single-stage | Constant-torque | National | $3,000–$4,100 |
| ML180V | Merit | up to 80.0 | Single-stage | Variable-speed | National | $3,200–$4,300 |
| ML193E | Merit | up to 93.0 | Single-stage | Constant-torque | National | $3,400–$4,500 |
| ML196E | Merit | up to 96.0 | Single-stage | Constant-torque | National | $3,600–$4,700 |
| ML296V | Merit | up to 96.0 | Two-stage | Variable-speed | National | $3,900–$4,800 |
| EL180NE | Elite | up to 80.0 | Single-stage | Constant-torque | Regional | $4,000–$5,300 |
| EL280E | Elite | up to 80.0 | Two-stage | Constant-torque | National | $4,200–$5,600 |
| EL196E | Elite | up to 96.0 | Single-stage | Constant-torque | National | $4,500–$5,900 |
| EL195NE | Elite | up to 95.0 | Single-stage | Constant-torque | Regional | $4,600–$6,100 |
| EL296E | Elite | up to 96.0 | Two-stage | Constant-torque | National | $4,800–$6,300 |
| EL297E | Elite | up to 97.0 | Two-stage | Constant-torque | National | $5,000–$6,500 |
| EL296V | Elite | up to 96.0 | Two-stage | Variable-speed | National | $5,200–$6,700 |
| EL297V | Elite | up to 97.0 | Two-stage | Variable-speed | National | $5,500–$7,000 |
| SL280V | Signature | up to 80.0 | Two-stage | Variable-speed | National | $5,800–$7,400 |
| SL280NV | Signature | up to 80.0 | Two-stage | Variable-speed | Regional | $6,100–$7,700 |
| SL297NV | Signature | up to 97.5 | Two-stage | Variable-speed | Regional | $7,000–$9,000 |
| SLP99V | Signature | up to 99.0 | Variable-capacity | Variable-speed | National | $7,000–$9,500 |
Three patterns are worth noticing before you read a quote. First, the four models flagged Regional are the ultra-low NOx units, which Lennox lists as first in class for meeting a 14 nanograms per Joule emissions limit. If you live in a California or Texas air district that requires low-NOx equipment, your menu is narrower and your price floor is higher. Second, series and efficiency are not the same axis. The Signature SL280V is an 80% AFUE furnace that costs more installed than a 96% AFUE Elite EL296E, because you are paying for variable-speed comfort rather than fuel efficiency. Third, the jump from constant-torque to variable-speed blower is worth roughly $300 to $500 within the same series, and it is the change most homeowners actually notice day to day.
What the K Suffix on a 2026 Lennox Quote Means
If your proposal says SLP99VK, SL280VK, or SL297NVK rather than the plain model name, that is not a typo and it is not a different furnace. Lennox states that model numbers designated with a K contain an on-board refrigerant detection system, and that the identical model without the K is the same product in every key respect including rating, performance, and specifications, minus that sensor.
The reason it exists is the A2L refrigerant changeover. Lennox has moved its air conditioners and heat pumps to R-454B, a mildly flammable A2L refrigerant adopted under the EPA AIM Act phase-down, and an indoor coil sitting on top of a furnace cabinet now needs leak detection. If you are replacing only the furnace and keeping an existing R-410A coil, you generally do not need the K version. If you are replacing the furnace and the outdoor unit together, expect it. Ask the dealer which one is on the order and whether the difference is priced into the quote, because the sensor version is not free.
For how Lennox prices the cooling half of a system, see our Lennox heat pump cost guide and the Lennox whole-system replacement cost guide.
Is a 96% AFUE Lennox Furnace Worth the Extra Money Over 80%?
In most of the country, yes, but the reason is not only the fuel bill. AFUE tells you what share of the gas you buy becomes usable heat in the house. An 80% AFUE furnace sends one dollar in five up the flue. A 96% AFUE furnace sends one dollar in twenty five. On a $1,200 annual heating bill that gap is roughly $200 a year, which pays back the upgrade in five to seven years in a cold climate and considerably longer in a mild one.
The part that rarely gets mentioned is the warranty gate. Lennox publishes a limited lifetime heat exchanger warranty on registered Elite and Dave Lennox Signature Collection furnaces, but only on the 90+ AFUE and oil models. The 80% AFUE versions of those same series get 20 years on the heat exchanger instead. Merit gets 20 years regardless of efficiency. The heat exchanger is the single most expensive component in a furnace and a cracked one is normally a full replacement, so the coverage difference has real dollar value even if you never use it.
Three situations where the 80% unit is still the right call:
- No practical venting path. A condensing furnace exhausts through PVC out a sidewall and produces acidic condensate that needs a drain. In a mid-house closet with no exterior wall nearby, the venting conversion can cost more than the efficiency upgrade saves.
- Very mild winters. In the Gulf South a furnace may run a few hundred hours a year. The annual fuel saving can fall under $80, which never repays the upgrade within the equipment life.
- A shared masonry chimney. Taking the furnace off a chimney it shares with a gas water heater usually forces a liner on the water heater, adding $800 to $2,500 that has nothing to do with the furnace.
Our HVAC cost by efficiency breakdown works the payback math across efficiency tiers, and gas vs electric furnace cost covers the fuel choice itself if you are not committed to gas.
What Rebates and Tax Credits Apply to a Lennox Furnace in 2026?
The federal Section 25C Energy Efficient Home Improvement Credit is gone for 2026 installations. The IRS states the credit applies to qualifying property placed in service on or after January 1, 2023 and before December 31, 2025, and ENERGY STAR states the furnace credit was effective for products purchased and installed between January 1, 2023 and December 31, 2025. A furnace you install this year does not qualify for the former $600 credit, which required an ENERGY STAR certified gas furnace at 97 AFUE or higher. Both sources were verified August 1, 2026.
This is worth stating plainly because a number of HVAC pricing pages still advertise a $600 federal furnace credit for 2026. If a contractor builds that credit into your payback math, the payback math is wrong.
What is live is a manufacturer promotion, and the fine print matters more here than on any other Lennox product. Lennox is running a national consumer promotion worth up to $1,550, and a furnace-only replacement does not qualify for any of it.
- What qualifies: a complete Lennox Ultimate Comfort System, meaning a gas furnace or blower coil plus an air conditioner or heat pump plus a thermostat. Replacing only the furnace earns nothing.
- The $250 anniversary add-on is heat pump only. Lennox limits the 250th Anniversary Special to the SL22KLV, EL21KLV, EL19KPV, EL16KP1, and EL18KSLV heat pumps. A furnace paired with an air conditioner tops out at $1,300, not $1,550.
- Purchase window: July 6 through August 14, 2026, from a participating Lennox dealer, with installation by August 21, 2026.
- Claim deadline: September 20, 2026 at 11:59:59 p.m. ET, submitted with the dealer invoice listing all models and serial numbers.
- Payment form: a Lennox Prepaid Mastercard issued after the fact, not a discount on the invoice, and prepaid cards carry expiration dates.
Lennox also offers 0% interest for 60 months on a qualifying system as an alternative to the rebate, not in addition to it. Qualified buyers make equal monthly payments over the promotion period, and the terms void if a payment runs 31 days late. If you are replacing the furnace and the air conditioner together anyway, run both numbers: on a $9,000 system the financing is often worth more than the $1,300 card. Our AC and furnace replacement cost guide covers whether pairing the two is worth it in the first place.
Utility and state programs stack on top of the manufacturer promotion and are now the larger opportunity in many territories, particularly gas utility rebates for 95+ AFUE equipment. Check your gas utility’s current offer before you sign, because those programs usually require pre-approval rather than a post-install claim.
What Warranty Comes With a Lennox Furnace?
Lennox splits coverage into a Basic Limited Warranty that applies automatically and an Extended Limited Warranty that requires registration within 60 days of installation. On a furnace the gap between them is wide enough that failing to register is one of the more expensive clerical mistakes a homeowner can make.
| Series | Unregistered Parts | Registered Parts | Heat Exchanger (90+ AFUE) | Heat Exchanger (80% AFUE) | Labor Trade-Down Option |
|---|---|---|---|---|---|
| Merit | 5 years | 10 years | 20 years | 20 years | 7 years parts + 3 years labor |
| Elite | 5 years | 10 years | Limited lifetime | 20 years | 7 years parts + 3 years labor |
| Signature | 10 years | 12 years | Limited lifetime | 20 years | 10 years parts + 3 years labor |
Four details that matter on a real install. Homeowners in California, Florida, Quebec, and Georgia for units installed on or after January 1, 2026 receive the extended coverage automatically without registering, which is a state-law consequence rather than a Lennox favor. Georgia is the recent addition, so a 2025 Georgia install and a 2026 Georgia install are not treated the same way.
The labor trade-down is genuinely worth considering on a furnace. Swapping an inducer motor or a control board in year six costs far more in labor than in parts, and three years of covered labor front-loads protection during the window when installation defects surface. Lennox offers the trade-down on every tier, and it is a choice you make once at registration rather than something you can add later.
The heat exchanger term is the number to read most carefully, because it is the one that varies by model rather than only by series, and because a cracked heat exchanger normally means a full furnace replacement rather than a repair. Verify the coverage on your own proposal against Lennox’s published warranty page before signing, and note that Lennox lists a separate lifetime heat exchanger exception for its legacy ML195 furnaces that does not extend to the current Merit models.
How Does Lennox Furnace Pricing Compare to Carrier, Trane, and Goodman?
Lennox spans a wider band than any other premium brand because it competes at both ends. The Merit line reaches down into budget territory that Carrier and Trane do not serve, while the SLP99V reaches an efficiency ceiling nobody else publishes.
| Brand | Installed Range | AFUE Range | Heat Exchanger Warranty | Position |
|---|---|---|---|---|
| Lennox | $3,000–$9,500 | 96%–99% | Lifetime (select models) | Budget to premium |
| Carrier | $3,200–$9,000 | 96%–98.5% | 20 years | Mid to premium |
| Trane | $3,500–$9,500 | 96%–97.3% | 20 years | Mid to premium |
| Goodman | $2,800–$7,000 | 96%–98% | Lifetime (select models) | Budget to mid |
Two things separate Lennox in this field. It publishes the highest AFUE in residential gas heating at 99.0 on the SLP99V, roughly a point and a half above Carrier’s ceiling and nearly two points above Trane’s. And it offers a lifetime heat exchanger warranty on qualifying 90+ AFUE Elite and Signature models where Carrier and Trane both cap at 20 years, which is a meaningful difference on a component that often outlives the rest of the furnace.
Treat all four as roughly interchangeable on build quality at matching tiers. The installing contractor is the larger variable in how a furnace performs over 20 years, and a well-installed Goodman beats a badly installed Signature every winter. For the full field including Rheem, York, and Daikin, see our furnace replacement cost by brand guide, and our best HVAC brands comparison ranks the manufacturers on reliability rather than price.
Why Do Lennox Furnace Quotes Vary So Much Between Dealers?
Lennox sells exclusively through an authorized dealer network and does not publish equipment prices. Its website shows a price guide of one to four dollar signs rather than a number. There is no list price to anchor against, no online retail channel, and no way to price-check a model number the way you can with an open-distribution brand. The predictable result is a wide quote spread for identical equipment, commonly 25 to 40 percent between the low and high bid in the same metro.
Furnace quotes diverge for a second reason that has nothing to do with the equipment. Two contractors looking at the same basement can reach different conclusions about whether the existing flue, gas line, return duct, and condensate path are reusable. One quotes a straight swap, the other quotes a swap plus $2,000 of venting and duct work. Both may be honest. The cheaper quote is only cheaper if the work it left out genuinely was not needed.
Five things to do before you sign anything:
- Get three quotes from separate Lennox dealers. With no published pricing, comparison is your only leverage.
- Demand the model number, not the series name. A quote that says Elite furnace could be an EL180NE or an EL297V, a $3,000 difference at the same input rating.
- Ask for the load calculation result in BTU and compare it against the input rating being quoted. If the answer is that they matched the old unit, that is not a calculation.
- Get the venting scope in writing. Whether the quote includes new PVC venting, a condensate pump, and a chimney liner for the water heater is the single largest line-item difference between bids.
- Get registration in writing. Ask the dealer to register the system before leaving and forward you the confirmation, since the 60-day window is the difference between 5 and 10 years of parts coverage.
If you are weighing a furnace against going all-electric, our gas furnace replacement cost guide covers the fuel-side economics and furnace replacement cost gives the brand-agnostic baseline this page sits inside.
Frequently Asked Questions
How much does a Lennox furnace cost installed?
A Lennox furnace costs $3,000 to $9,500 installed in 2026, depending on the series, the AFUE rating, and the BTU input your home needs. Merit runs $3,000 to $4,800, Elite runs $4,000 to $7,000, and the Dave Lennox Signature Collection runs $5,800 to $9,500. The most common project, an 80,000 BTU Elite 96% AFUE furnace swapped into existing ductwork, lands between $5,000 and $6,300.
Which Lennox furnace is the most efficient?
The Dave Lennox Signature SLP99V is the most efficient furnace Lennox builds, rated up to 99.0 AFUE. That is the highest AFUE available in a residential gas furnace from any major brand, and it costs $7,000 to $9,500 installed. The regional SL297NV follows at up to 97.5 AFUE, and the Elite EL297V and EL297E reach up to 97.0 AFUE for $5,000 to $7,000 installed. Above roughly 96 AFUE the added fuel savings are small, so the SLP99V is usually bought for its variable-capacity comfort rather than its payback.
Is the federal furnace tax credit still available in 2026?
No. The Section 25C Energy Efficient Home Improvement Credit applied to qualifying property placed in service before December 31, 2025. A furnace installed in 2026 does not qualify for the former $600 federal credit for a high-efficiency gas furnace. Several HVAC pricing pages still advertise it for 2026 installs, which is incorrect. Utility rebates, state programs, and the Lennox manufacturer promotion are the remaining levers.
What is the difference between Lennox Merit, Elite, and Signature furnaces?
The three series differ in burner staging, blower motor, efficiency ceiling, and heat exchanger warranty:
- Merit is the entry line at 80 to 96 AFUE, mostly single-stage apart from the ML296V, with a 20-year heat exchanger warranty, for $3,000 to $4,800 installed.
- Elite is the mid line at 80 to 97 AFUE in both single-stage and two-stage versions, with a limited lifetime heat exchanger warranty on 90+ AFUE models, for $4,000 to $7,000 installed.
- Signature is the premium line at 80 to 99 AFUE, topping out with variable-capacity firing and variable-speed blowers throughout, for $5,800 to $9,500 installed.
- Parts coverage improves with tier: registered coverage is 10 years on Merit and Elite, and 12 years on Signature.
What does the K in a Lennox furnace model number mean?
A K in the model number, such as SLP99VK instead of SLP99V, means the furnace ships with an on-board refrigerant detection system. Lennox states the two versions are otherwise identical in rating, performance, and specifications. The K version exists because A2L refrigerants such as R-454B require leak detection when the furnace shares a cabinet with the indoor coil. If you are pairing a new Lennox air conditioner or heat pump with the furnace, expect the K variant on your quote.
What warranty comes with a Lennox furnace?
Lennox coverage depends on whether you register the system within 60 days of installation:
- Unregistered: Merit and Elite get 5 years parts, Signature gets 10 years parts.
- Registered within 60 days: Merit and Elite rise to 10 years parts, Signature to 12 years parts.
- Heat exchanger: limited lifetime on registered 90+ AFUE Elite and Signature models, 20 years on the 80% AFUE versions and on all Merit models.
- Labor trade-down: every tier can swap parts coverage for 3 years of labor, which is 7 years parts on Merit and Elite and 10 years parts on Signature.
- Automatic coverage: homeowners in California, Florida, Quebec, and Georgia for units installed on or after January 1, 2026 receive the extended coverage without registering.
For a personalized range based on your home size, climate, and efficiency target, use our free HVAC cost estimator. To see where Lennox furnace pricing sits against the wider market, start with our furnace replacement cost guide, and compare the whole-system picture in our HVAC replacement cost guide.
Last updated: August 2026. Installed price ranges reflect national averages and vary by region, dealer, and home condition. Model specifications, AFUE ratings, warranty terms, and promotion details verified August 1, 2026 from Lennox.com. Tax credit status verified August 1, 2026 from the IRS and ENERGY STAR.