A definitive guide to the best high-efficiency propane and natural gas furnaces in Canada, including the most energy-efficient and most reliable heating systems, the quietest models, the furnaces with the best warranties, top features, and the overall best furnace brands.
Here at FurnacePrices.ca, our goal is to make it easier for Canadian consumers to research, understand, and select the right heating systems for their homes. Every year, we look into the best furnaces from all the major brands to evaluate and compare them, so you don’t have to.
We base our evaluations on criteria such as pricing, features, warranties, and efficiency ratings & ENERGY STAR® models to find the stand-out models from North America’s favourite manufacturers.
In this guide, we’ll give you an in-depth comparison of the best furnaces on the market today in these categories so you can easily decide for yourself which make, model, and brand is right for your family’s comfort.
Table of contents
- Who Should You Trust to Install Your New Furnace?
- How We Evaluate the Best Furnaces
- How We Assess the Most Reliable Furnaces
- Furnaces with the Best Warranty Coverage
- The Best Furnaces by Budget
- Furnaces with the Best Features
- Most Efficient Furnaces
- Getting the Most from Your Furnace
Who Should You Trust to Install Your New Furnace?
The HVAC contractor you choose can be every bit as important as the brand and model you pick. We recommend buying from an experienced and established company that will provide reliable and quality workmanship, professional installation, and dependable ongoing support for years afterwards.
To help you find a local HVAC expert with all the right credentials, we’ve created an independent contractor certification program. We vet experts from all across the country for important factors like experience, reputation, training, licensing, quoting process, and much more.
When it’s time for you to buy, install, or maintain a furnace, this will make it easier for you to find a dependable and trustworthy contractor.
How We Evaluate the Best Furnaces
One of the first things people often consider when buying a new furnace is the brand, but there are several more important factors to think about when upgrading your heating system.All brands have unique advantages and disadvantages, but we focus more on the individual units rather than the manufacturers that make them. Just a handful of companies own most of the HVAC brands you’re familiar with, so overall most brands are quite similar.
Here are the top things to consider when you’re buying a new furnace:
- Look for a furnace with a high, cost-saving AFUE rating: the most efficient furnace on the market right now uses virtually 99 percent of the fuel it consumes
- If you have the budget for it, a higher-performing two-stage or variable-speed modulating furnace will provide better cost-savings, quieter comfort, and more consistent temperatures
- Excellent warranty coverage could save you thousands over the lifespan of your furnace (although the labour warranty you get from the local HVAC contractor who installs it is arguably just as important, if not moreso)
- Get the best value for your budget, whether you’re looking for something entry-level, mid-range, or top-tier
- Additional features and pioneering technologies can make your life easier, and those include remote Wi-Fi access to the system, noise-reducing technology, smart thermostat communication, and more
- It’s important to get a system that’s the right size for your home and heating needs
- Have the unit installed and maintained regularly by a certified HVAC technician
- Look for furnaces that are made with quality materials and construction
- Find an HVAC dealer you trust and can rely on when buying your furnace or having it installed and serviced
All of these factors (and especially regular servicing, proper care, and professional installation) are far more important when it comes to furnace reliability than the brand you buy.
To help you find a dependable and trustworthy HVAC contractor for new furnace installations, request a free estimate from our Certified Local HVAC Contractors, to find an experienced high-quality company.
How We Assess the Most Reliable Furnaces
RELATED ARTICLE: The Truth About Furnace (and A/C) Reliability
Having a reliable furnace isn’t just a luxury in Canada—it’s a necessity. Our winters are far too cold and long to worry about whether your furnace will last another season, so getting a reliable furnace is crucial.
Fortunately, manufacturing standards and competition in the market mean that all HVAC brands generally offer dependable and long-lasting furnaces. But getting a reliable furnace is about more than picking the right brand and model.
A dependable furnace also requires:
- Being the right size and capacity for your home
- Installation by a professional HVAC expert
- Regular maintenance and service
- Timely repairs when necessary
These added variables make it difficult to definitively evaluate which brands are most reliable because the contractor or company that installed it also plays an important role, among other things.
Why Customer Reviews Aren’t the Best Source for Evaluating Furnaces
Furthermore, any data on furnace malfunctions and breakdowns, including consumer reviews, tend to be skewed by a number of factors. For example, larger and more popular brands tend to have more complaints by customers simply because there are far more people that have these units installed overall.
Even if the percentage of people that encounter serious issues is relatively low, online feedback may give the impression that problems are more common than they really are.
People are also much less likely to take the time to go online and post a review about their furnace quietly doing its job. Instead, they’re far more likely to post a review when something goes wrong. For this reason, consumer reviews of furnaces often appear to have a negative slant, regardless of brand.
Using Warranty Coverage as the Standard of Excellence
We’ve chosen to compare warranty coverage as the main gauge of reliability. In contrast to customer reviews, it’s a much more tangible and objective way to compare brands. Although warranty coverage doesn’t directly indicate reliability, it does offer a good indication of the type of guarantee offered by the manufacturer.
A manufacturer that backs their products with an excellent warranty is putting their money where their mouth is because the warranty terms tell you how long you can expect to be covered in the event something goes wrong.
Ultimately, most modern furnaces that are sized correctly by a professional and installed by an experienced and certified technician tend to be quite reliable, with few major differences in reliability across most brands and manufacturers.
That’s not to say that furnaces never have issues and never break down, but for every person complaining online about their furnace malfunctioning, there are thousands of homeowners with a furnace humming along for years.
Now that we’ve covered that, let’s have a look at the best high-efficiency furnaces on the market in Canada for 2020!
RELATED ARTICLE: The TRUTH About Online Furnace (and AC) Reviews
Furnaces with the Best Warranty Coverage
Warranty coverage isn’t just an important indicator of the quality of your furnace: it could also save you hundreds or thousands of dollars.
Major components like heat exchangers can cost thousands of dollars to replace or repair, so a good warranty could mean the difference between you paying out of pocket or the manufacturer covering the cost.
Most manufacturers have base warranties with limited terms and registered warranties with extended coverage. To be eligible for the extended coverage, you’ll have to register the unit online with the manufacturer within 60 to 90 days of installation. Your contractor may do this for you, which highlights the importance of choosing a dependable contractor.
Some of the most common warranties include parts, heat exchanger, and unit replacement warranties, but some manufacturers also have labour warranties to cover problems that crop up in the first couple years.
- Parts warranties cover the cost of replacing parts if something goes wrong
- Heat exchanger warranties are specifically for the heat exchanger, and promise a new one if the original fails
- Unit replacement warranties will cover the cost of replacing the entire furnace should a major component fail
- Labour warranties cover the cost of an HVAC technician’s time if your furnace needs repairs
Generally speaking, the economy models within any brand will have the most basic warranties with the lowest coverage. Mid-budget models will have more extensive and longer warranties. Finally, a brand’s premium-priced models will have the most comprehensive and longest warranties.
|Budget||Brand and Model/Series||Warranty Details|
|Economy||KeepRite Ion Series||10-year parts, lifetime heat exchanger, 10-year unit replacement|
|Economy||York (all)||10-year parts, lifetime heat exchanger, one-year labour|
|Economy||Comfortmaker Ion Series||10-year parts, lifetime heat exchanger, 10-year unit replacement|
|Medium||Luxaire Acclimate Series||10-year parts, lifetime heat exchanger, one-year labour, 10-year complete assurance pledge|
|Medium||Daikin DM97MC||12-year parts, lifetime heat exchanger, 12-year unit replacement|
|Medium||Napoleon 9700 Series||10-year parts, lifetime heat exchanger, 15-year unit replacement|
|High||Lennox Dave Lennox Signature Collection||10-year parts, lifetime heat exchanger|
|High||Carrier (all)||10-year parts, lifetime heat exchanger|
The Best Furnaces by Budget
For many homeowners, furnace cost is one of the most important considerations when upgrading to a newer furnace. The good news is that furnace prices range from affordable for standard models to expensive for upscale models, so depending on your budget and what you want, you’ll still be able to find something that suits your needs.
It’s important to note that some brands effectively charge a premium for the brand name, but their more expensive models often have additional features as well, such as variable-speed blowers, better warranties, higher efficiency ratings, and new technologies.
That’s not to say that lower-cost brands aren’t as good. Many of them still have models that offer great features too. There are also mid-priced brands that make both basic and more advanced furnaces, so it’s important to compare the price of a specific furnace against other important things like:
- Furnace features and technologies
- Warranty terms
- Your budget
RELATED ARTICLE: The TRUTH About Furnace (and A/C) Pricing
As for which furnaces have the best prices, the brand itself is less important than the individual models. Every brand usually has a good sweet spot, with models that offer decent performance at a reasonable price.
HVAC manufacturers typically have three furnace tiers: entry-level, mid-range, and top-tier. The tier will impact not only the price, but also what features and warranty terms you get.
The entry-level models will be the most affordable, but they’ll be the most basic in terms of technology and coverage. Top-tier models will be the most expensive and the most stacked in terms of features, energy-efficiency, and warranty coverage.
Let’s look at some of the stand-out furnace models of 2020 based on price and value:
|Brand/Model||AFUE||Price Range||Top Qualities|
|York LX Series TM9E||95%||$3,000 – $3,835||Single-stage, compact, self-diagnostics|
|Comfortmaker QuietComfort - G96VTN||96%||$3,665 – $4,330||Two-stage, variable-speed blower motor, quiet operation|
|Goodman GMVC96||96%||$3,835 – $4,670||Two-stage, variable-speed, ComfortBridge technology|
|Brand||AFUE||Price Range||Top Qualities|
|Coleman LX TM9V||96%||$4,000 – $4,750||Two-stage, ECM blower, secondary heat exchanger, communicating control|
|Bryant Preferred 926T||96.5%||$4,335 – $5,170||Two-stage, SmartEvap, Perfect Heat and PerfectLight technologies, Hybrid Heat capability.|
|Amana ACVM97||97%||$5,500 – $6,500||Modulating, variable-speed, CoolCloud app compatible, ComfortBridge technology|
|Brand||AFUE||Price Range||Top Qualities|
|Trane S9V2-VS||97%||$4,665 – $5,830||Two-stage, secondary heat exchanger, Comfort-R technology|
|Carrier Performance 59TP6||96.5%||$4,835 – $6,170||Two-stage, variable-speed, SmartEvap humidity control technology|
|Lennox SL297NV||97.5%||$6,170 – $7,500||Modulating, ultra-low NOx emissions, variable-speed, smart thermostat compatible|
Furnaces with the Best Features
Some HVAC manufacturers invest in novel features and technologies that give them a leg up over the competition, make their furnaces more appealing, and make your life more comfortable and convenient.
The economy models from any brand will have the fewest additional features whereas the more expensive models will come more fully loaded, but some manufacturers put more emphasis on new tech than others.
Before we get into what features you can find with specific models, here’s a quick description of some of the best specifications features to look for:
- Smart thermostat compatibility so you can automate your heating needs throughout the day and gain remote Wi-Fi access to the controls
- Noise-reducing features that promise quiet operation
- Self-diagnostics systems that monitor performance and alert you to maintenance needs and potential problems
- Unique features that are designed to enhance performance and comfort
- Built-in or add-on air purification and humidity control systems
- Zone control capabilities so you can set different temperatures in different rooms
- Variable-speed fans and blower motors for quieter operation, better humidity control, and more even temperatures
- Features and specially designed components that increase the longevity of the furnace
- Hot surface ignition systems that don’t rely on pilot lights and don’t have any maintenance problems or downtime because of pilot issues
- Two-stage or modulating gas valves that are quieter, more efficient, and eliminate temperature swings and fluctuations
Best Furnace Features for Energy Efficiency
Lennox’s Power Saver technology involves a constant torque motor that consumes less energy while also keeping your home more comfortable thanks to on-demand airspeed adjustment. Lennox is a premium brand and this technology is only available with their mid-range and top-tier models, so you will need a higher budget to get a furnace with this feature.
Napoleon’s EnerSave technology works similarly, and reduces electricity use and noise when the system is running on the continuous fan mode.
Another feature from Napoleon that increases efficiency and reduces costs is the vortex turbulator, a proprietary heat exchanger that recycles heat from exhaust gases.
Best Furnace Features for Control and Convenience
Many HVAC manufacturers have their own programmable smart thermostats that can save you money by optimizing how and when your furnace heats your home. These devices can also ensure that your home is always at the perfect temperature when you’re home, and in energy-saving modes when you’re away. Here are some of the perks that most smart thermostats have in common:
- Most can be controlled remotely with a smartphone or tablet (and some even with Amazon Alexa)
- They allow you to monitor the system
- You can keep an eye on performance and energy use
- You can change temperature settings on the fly
- You can control temperature, humidity, and airflow settings
- They let you program different temperature settings based on days of the week and times of day
- They provide problem reports, system diagnostics, and maintenance reminders
- They can send updates to your local HVAC technician for faster service
- They give local weather updates
Here’s a list of the smart thermostats that can be paired with different brands’ furnaces, and which makes/models are compatible with those devices:
|Carrier and Tempstar||Infinity System Control||Ion Series|
|York||Affinity™ Wi-Fi Residential Communication Control||Affinity Series|
|Luxaire and Coleman||Hx3 Touch-Screen Thermostat||LX Series|
|Ruud and Rheem||EcoNet||Ultra and Prestige Series|
|Lennox||iComfort S30||Dave Lennox Signature Series|
|KeepRite, Heil, and Comfortmaker||Ion System Control||Ion Series|
|Daikin||Daikin One+||DM97MC and DC97MC models|
|Armstrong||Comfort Sync Thermostat||Pro Series|
Best Furnace Features for Healthy Air and Humidity Control
- Both Carrier and Bryant have some furnaces that are equipped with SmartEvap, a humidity control system that works with your air conditioner in summer to pull moisture from the air. This can improve indoor air quality by eliminating moisture problems, but it can also save you money and keep you more comfortable on those muggy summer days.
- The ClimaTrak Technology that’s available with select York, Luxaire, and Coleman models allows your local HVAC specialist to customize the furnace’s humidity control capabilities by setting the system to work optimally in either a dry, temperate, or humid climate.
- Daikin’s Premium Air Cleaner is a filter that’s superior to standard furnace filters, so it can help keep the air in your home fresher, cleaner, and clear of allergens and pollutants.
- Similarly, Trane has CleanEffects, which is another advanced furnace filter that cleans the air of dust, allergens, and other pollutants and contaminants.
- American Standard also has a special filter you can purchase separately, the AccuClean Whole-Home Air Cleaner, which can eliminate up to 99.98 percent of contaminants from the air.
- Bryant doesn’t have a proprietary filter, but they do have the TrueSense technology, a dirty filter detector that notifies you when it’s time to clean or replace the furnace filter.
- For their part, Napoleon’s 9700 series furnaces come equipped with their HomeShield UV, a special UV lamp that purifies the air as it goes through the furnace.
Best Furnace Features for Durability and Longevity
- Top-tier furnaces from Goodman and Amana have the CoolCloud app, which allows certified HVAC experts to connect to your furnace settings and configure and diagnose problems faster and more easily. This ensures proper maintenance and repairs, which can increase the life of your unit.
- Some Lennox furnaces have a similar heat exchanger, the clamshell Duralok Plus heat exchanger that’s made from high-quality ArmorTuf steel.
- Armstrong’s EHX Technology is another proprietary heat exchanger design that comes standard in every Armstrong furnace to increase durability by eliminating hot spots, while also improving heat exchange, airflow, and efficiency.
- Most Tempstar, Heil, and Comfortmaker furnaces have a special Rigid Press Joint (RPJ) heat exchanger that is more durable and long-lasting because it has a weld-free interlocking clamshell design.
- American Standard has improved furnace longevity by creating the Vortica™ II Blower, which isn’t just efficient, but also rust-, corrosion-, and crack-resistant.
- Select Ruud and Rheem furnaces are equipped with the PlusOne Diagnostics system, an LED display that provides in-depth diagnostics that make service and repairs easier.
- Trane furnaces come with stainless steel heat exchangers for increased heat and corrosion-resistance
Best Furnace Features for Improved Comfort
Many of the features in this category are technologies that monitor the outdoor temperature and your furnace settings, and adjust heating output, humidity, and airflow to optimize indoor comfort levels. These include:
- ComfortBridge from Amana and Goodman
- Greenspeed® Intelligence from Carrier
- AirFlex from Lennox
- Comfort-R technology from Trane and American Standard
- Integrated Furnace Control from Napoleon
- Perfect Heat from Bryant
Best Furnace Features for Quiet Operation
Modern furnace brands know that winter comfort isn’t just about temperature—it’s also about silence. That’s why many modern furnaces have features or design specifications that reduce noise, such as two-stage gas valves, modulating burners, and variable-speed blower motors.
Other manufacturers go one step further and create special sound-reduction features that limit noise, including unique fan blade designs, additional cabinet insulation, and gradual start-up systems. Here are some of the best sound-reducing features to look for in some brands’ select models:
- Armstrong’s Quiet Combustion Technology
- Napoleon’s Whisper Quiet
- Coleman’s WhisperDrive Comfort System
- Bryant’s QuietTech™
- Luxaire’s Silent Drive Comfort System
- Lennox’s SilentComfort Technology
Most Efficient Furnaces
Efficiency is another common thing people consider carefully when choosing a new heating system. The more efficient your furnace, the more you’ll save on your heating bills every year.
Just about every HVAC brand sold in Canada has a model with an AFUE rating of at least 96 percent, so no matter what your budget is, you’ll be able to find a high-efficiency furnace for your home.
Before we go over the models with the highest efficiency ratings on the market, it’s important to mention a few things about how tier and price can impact efficiency:
- The most affordable economy furnaces tend to have single-stage gas valves and fixed-speed blower motors, so they’re less efficient (AFUE ratings from 92 to 93 percent), as well as noisier and have more temperature fluctuations.
- Mid-budget mid-range furnaces typically have two-stage gas valves and multi- or variable-speed blower motors, so they’re more consistent, quieter, and more efficient (95 to 96 percent AFUE). Many reasonably popular brands have these features, including KeepRite, Payne, and many others covered above.
- Premium, top-tier furnaces are the most expensive, and these are often modulating furnaces with variable-speed blower motors, so they offer the best efficiency (97 to 99 percent AFUE), the quietest operation, the most consistent temperatures, and the best humidity control.
These days, all HVAC manufacturers, from the most economy brands to the highest-end names, have models that are ENERGY STAR certified, which is a great way to know you’re getting an energy-efficient and more environmentally-friendly heating system. This is a bonus when considering the impact of the carbon tax on heating costs. We always recommend opting for an ENERGY STAR furnace when possible.
Now let’s look at the most energy-efficient furnaces on the market, broken down by budget. You’ll note that a higher cost doesn’t necessarily translate to a higher efficiency rating, and just about every manufacturer in Canada has at least one model with an excellent efficiency rating:
|$4,330 – $5,500||Comfortmaker Ion™ 98 - G97CMN||98%|
|$4,330 – $5,500||York Affinity YP9C||98%|
|$4,330 – $5,500||KeepRite Ion 98 G97CMN||98%|
|$4,330 – $5,500||Goodman GMVM97||98%|
|$4,330 – $5,500||Luxaire Acclimate Series LP9C||98%|
|$4,330 – $5,500||Heil Ion™ 98 - G97CMN||98%|
|$4,330 – $5,500||Colemane Echelon CP9C||98%|
|$5,170 – $6,000||Daikin DM97MC||98%|
|$5,170 – $6,000||Tempstar Ion™ 98 - F97CMN||98%|
|$5,170 – $6,000||Ruud Ultra Series U98V||98%|
|$5,170 – $6,000||Bryant Evolution®️ – 987M||98.3%|
|$5,500 – $6,750||American Standard Platinum 95||97.3%|
|$5,500 – $6,750||Amana AMVM97||98%|
|$5,500 – $6,750||Rheem Prestige™ Series R98V||98.7%|
|$5,830 – $7,500||Trane XC95M||97.3%|
|$5,830 – $7,500||Carrier Infinity Greenspeed 59MN7A||98.5%|
|$5,830 – $7,500||Lennox Signature Collection SLP99V||99%|
Getting the Most from Your Furnace
No matter what furnace you end up choosing, it’s important to have it installed by an experienced, licensed & certified HVAC technician. This will ensure the unit is installed properly, is functioning optimally, and is the correct size for your home. Plus, it will prevent potential problems down the road, and could save you plenty on unnecessary repair bills.
FurnacePrices.ca has made choosing an experienced & reliable contractor easy with our extensive independent certification process.
A: Contrary to popular belief, reliability doesn’t vary much from brand to brand. A much bigger factor is that the furnace is the correct size, properly installed by a licensed technician, and adequately maintained with annual service and timely repairs when necessary.
An accurate in-home assessment, conducted by a certified technician, will assist you with selecting the appropriate BTU for your home heating system. Selecting the proper size of furnace for your home will assist you in achieving a reliable high-efficiency natural gas furnace, regardless of which brand you choose.
We would be happy to help you obtain a free, no-obligation furnace quote from one of our experienced local distributors.
A: A variable-speed furnace is one that has a variable-speed blower motor. Single-speed blower motors only have two settings: ON and OFF. A variable-speed blower motor has many speed settings, so it can deliver air slowly, efficiently, quietly, and consistently.
A: An ECM motor is an electronically commutated motor that varies the speed using electronic controls, so they’re quieter and more efficient than standard PSC motors. Natural Resources Canada has reported up to 70% less energy use when the furnace is equipped with an ECM motor.
It used to be that you’d have to budget more for a mid-range or top-tier furnace to get an ECM motor, but it’s becoming more common for furnace manufacturers to equip all of their furnaces (or at least a selection from every tier) with these more sophisticated motors.
A: A furnace with a modulating burner is more sophisticated and more expensive because it allows your furnace to adjust to fluctuations in temperature, enabling you to better control your comfort levels and improve your energy efficiency and cost-savings. However, modulating burners are found in the upper midrange and premium tier high-efficiency natural gas furnaces. In other words, they cost more, but they’re more efficient, quieter, and more consistent.
A: The furnace’s heat exchanger is responsible for producing heat from the burned gas. In order to produce more heat from the same amount of burned gas, some high-efficiency furnaces also have a secondary heat exchanger that traps and recycles heat from exhaust gases. This secondary heat exchanger is usually made with stainless steel or lined with hard plastic to limit the negative effects of corrosive acidic condensates, which may result from the use of the secondary heat exchanger. If you want a furnace with two heat exchangers, then look for condensing furnaces or furnaces with the feature dual heat exchange. This feature is becoming more common among entry-level and mid-range furnaces.
A: The ignition system is the component that starts the process of heating the air. In older furnaces, this process typically started with a pilot light. Modern furnaces are more likely to have an electronic ignition system that can quickly handle temperature fluctuations, keeping your home warm and comfortable. The cream of the crop in terms of ignition systems is hot-surface ignition.
A: In short, yes! No matter which brand or type of furnace you select, the installation process of the furnace is arguably the most important factor. An experienced and certified HVAC technician will ensure a proper installation of your new high-efficiency natural gas furnace.
Correct installation by a certified technician is important for the overall reliability of the furnace, as well the safety of you and your family. An incorrectly installed furnace can pose a huge risk to the home and your family.
When purchasing a high-efficiency natural gas furnace, you want to ensure that the furnace is the correct size and that the BTU output is the correct amount for the size of your house. If your furnace is too big or small for your home, it will likely function irregularly, which will lead to damage over time, poor heating capacity, incorrect moisture levels, and other problems.
A: Air filtration add-ons are a great way to improve the function and performance of your furnace while also improving indoor air quality. Some furnaces come with an electrostatic filter, which works by using an electrical charge to attract particles. Other furnaces come with a HEPA (high-efficiency particulate-arresting) filter or other proprietary filters. These filters work by reducing the amount of dust, dirt allergens, pollutants, and contaminants that end up in the heating system. Some furnaces even come with special UV lamps that purify air.
A: Most modern furnaces have special features and designs that reduce noise. Here are a few noise-reducing features that are included in many types high-efficiency natural gas furnaces:
1. ECM Motor
2. Variable Speed
5. Insulated cabinets
6. Soft-mounter blowers and motors
7. Soft or gradual startup and stop
A: As you narrow down your top three high-efficiency natural gas furnace options you will want to take a close look at the warranty package that each brand offers.
Specifically, look at:
The parts warranty – regular maintenance and service is important to ensure that your high-efficiency natural gas furnace is running properly. However, even with annual maintenance parts can fail over time. Be sure to check the warranty to see which parts are covered under warranty.
The heat exchanger warranty – a broken heat exchanger is one of the costliest elements to repair, so it is important to ensure that whichever brand you choose has a heat exchanger warranty that protects you from an expensive repair.
Years covered under warranty – many plans typically last 10 years (limited), although certain premium brands do cover specific parts for the lifetime of your furnace. For example, lifetime heat exchanger warranties are becoming very common among most manufacturers, especially with their mid-range and top-tier models.
When to register your high-efficiency natural gas furnace: failing to register your new high-efficiency furnace within the specified number of days (typically the first 60 to 90 days) can result in a reduced or null and void warranty.