Lennox Furnaces

Everything you need on Lennox Furnaces, including model details, industry rankings and customer reviews, all in one place.

Lennox Furnace Overview

Lennox makes gas and oil furnaces. For each of these types, it sells a few different categories of furnace, stratified by price and efficiency. Energy efficiency is described in terms of Annual Fuel Utilization Efficiency (AFUE), which describes what percentage of the energy in fuel is converted into thermal energy for the house.

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Consumer Reviews of Lennox


  • Very Satisfied
  • Somewhat Satisfied
  • Neutral
  • Somewhat Unsatisfied
  • Very Unsatisfied
  • #15 of 86 Furnaces
  • 35.97% of customers recommended

Gas Furnaces

Lennox’s gas furnaces range in efficiency from 80% AFUE to more than 98% AFUE. Efficiency does not directly correlate with price; there are furnaces with 80% efficiency in all three furnace categories.

The Merit Series of furnaces is the least expensive. Of these, the G40 is the most basic unit (with 80% AFUE). The ML193 is similarly basic, but does boast somewhat higher efficiency (93% AFUE), due to the separation of the blower compartment.

Within the more expensive Elite series, the G50 (single-stage), G60 (two stage) and G60V (two-stage, variable-speed electric motor) are relatively inefficient (80% AFUE). These models use extra insulation, and consequently produce less noise. They also use somewhat more durable materials. The G60 has two operational stages, which allows it to operate at a lower speed most of the time.

 [ Lennox Series : Elite ]

The G51, G61, G61V, and G71P have higher efficiencies (92%, 95%, 95% AFUE, respectively). They run more quietly than other models because of special insulation. The materials are also better, and the heat exchangers for these models are guaranteed to last longer.

The two Dave Lennox Signature furnaces are the most expensive. The SL280V has an AFUE of only 80%, but its fan has the capacity to help cool a house during the summer. This model is also billed as especially quiet.

The top-of-the-line model is the SLP98V and has the extraordinary AFUE of 98.2%. This efficiency is due to various features, including a heat exchanger to capture excess heat, the ability to draw from multiple fuel sources, and compatibility with an advanced digital thermostat.

Oil Furnaces

There are fewer models of oil furnaces.

The O23 and O25 both have intermediate prices and efficiency (83% AFUE). These are basic models without many features.

The O23V is more expensive but is just as efficient as the other two. It does have better insulation and runs more quietly. It also operates at variable speeds, which means that on days with less heating to be done it produces less noise and saves energy. The O23V also has a humidity control feature.

O23 and O23V use Beckett burners; O25 uses a Riello burner.

Care and Maintenance

Lennox recommends having both gas and oil furnaces checked by a certified technician on a yearly basis. Homeowners should also clean or replace their filters every few months.


The furnaces are covered by warranties lasting a minimum of five years. Heat exchanger components typically fall under a longer warranty ranging from twenty years to the whole lifetime. The five-year parts warranty can be extended to ten years for an additional fee.

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Lennox Furnace Reviews

Showing 1-5 of 236 reviews

"Never buy a Lennox"

3.0 rating

I have no idea whether the problem is with the furnace or the only people who are allowed to service it. Terrible>>> Do not buy one, because there are only their "professionals" who can service them…They have been here five times in the last year and still have not fixed it.

p l


"Lennox Furnace is a piece of junk"

1.0 rating
Very Unsatisfied

I have a 4-year-old Lennox Elite Oil Furnace that is junk. It was poorly installed (fuel oil running out onto the floor from the outside filter forming a large pool on the floor 2 days after installation) and has repeatedly leaked fuel oil inside the furnace. Fuel oil drips from under the assembly. I have had the authorized dealer/service firm (McKean in Washington, Pa) in here multiple time to fix it, and it just continues to leak. In November of 2016, I spent a 3 week period largely without heat. I gave up every vacation day, personal day and sick day for that entire year to be off work so McKean could come in here nearly every day. Got it started when they got here, only to have it stop, leaking oil and with the lockout light blinking in as little as an hour. They have replaced multiple parts. They put shims in to lift one side. They most recently (in the last 2 weeks) replaced the entire assembly. It still leaks. I have to remove the front and wipe fuel oil several times a day or the air filter gets soaked. Even so, the filter gets oil on it (from the top and bottom) and has to be replaced every several days or it stinks. The house smells like fuel oil. I have contacted Lennox corporate several times. They refer me back to the dealer (who is now charging me for failed repairs, $300 the last time) and to the district rep (who is not only no use, but offers inappropriate comments – like not understanding why I am upset about this and that I need to confront their authorized dealer on these charges for failed repairs). I'm beginning to think that being a retired, unmarried woman may have something to do with why I am being ripped off and run over. I paid $3,500 for this furnace 4 years ago, and have paid close to $600 more for failed repairs. I have never had an experience like this in my life. Short of litigation against Lennox and their authorized dealer/service (which this may come to), I'm not sure what to do next. Is there anyone out there who fix this junk Lennox furnace? If so, you can respond via email or pm me on Facebook. In the meantime, I'm letting others know about my experience so that they can make an informed decision as to the brand of furnace they purchase and from which dealer.

Lynn Fischer


"Costly, high maintenance"

1.0 rating
Very Unsatisfied

The advertising budget should be spent on trying to get quality.



"This product is no good."

1.0 rating
Very Unsatisfied

Bought unit and furnace in 2015 couple of months furnace froze.techinan came and fixed it. Then last year 2017 had to call technician to come cause found water leaking. Technician came out and fixed it. I pay every month, so they can come and services my furnace. Of course technician said everything okay. Well winter has been pretty cold, well we would sat heater at 79 and up 80 degrees, and it would not come on. House would be at 69 degrees and still heater would not come on til hour later. Technician came out twice charging $75.00. said it was a part that was needed. Again I had to call for them to come out cause it was doing the same thing. Strand's brothers is the company that we went through to get the Lennox Ac. So I'm told that it's a part that is freezing up and delays the gas to flow through. After I have been complaining about it. Was told that I have to pay for the labor of $199.00 for them to come out and install. I don't think I have to for a them to come and put in a defective part that should have been check in the first place. I would not recommend strand's brothers or Lennox.


Austin, TX

"Costco Lennox Heating & Airconditioning Installed October 2017"

5.0 rating
Very Satisfied

We had a Engineer Chris who give us an estimate on replacing our York Heating and air conditioner. This was our third company giving an estimate. What was impressive, is Chris was the only one who asked us a series of questions. It was what he needed to give us the system that would best suit our needs. Chris was very professional, and extremely knowledgeable. Two months after the installation, he came back to look over the entire installation, and asked us if we were satisfied. Our new Lennox, is quieter, it will circulate the air from the living room to the back bedrooms when using the fireplace. We went with 80% efficiency, because after talking to Chris, it was the best in meeting our needs. The installers Rob and Scott, worked all day without a break, and did a great job. We are Costco members, and went through Costco. Both my husband and I couldn't be happier with our choice.

Donna Simale

Schaumburg, IL

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