What Makes a New Furnace Energy Efficient

Choosing a new furnace is a significant decision for any homeowner. Given that a furnace is a substantial investment and a key component of your home’s comfort system, it's essential to select a model that is not only reliable but also energy efficient. Energy-efficient furnaces are designed to provide the same level of warmth and comfort while using less fuel, which translates to several important benefits.

First and foremost, energy-efficient furnaces help reduce your utility bills. By maximizing the amount of fuel converted into heat, these furnaces ensure that you get the most out of every dollar spent on energy. This efficiency means that less energy is wasted, and your heating costs are minimized over the lifespan of the furnace.

Beyond cost savings, investing in an energy-efficient furnace also has a positive environmental impact. These furnaces produce fewer emissions than their less efficient counterparts, reducing your home's carbon footprint and contributing to a healthier planet. With concerns about climate change and environmental sustainability growing, making eco-friendly choices in home heating is more important than ever.

Energy-efficient furnaces often come with advanced features that enhance your home's overall comfort. Innovations such as two-stage heating, variable-speed blowers, and sealed combustion chambers not only boost efficiency but also ensure more consistent and even heating throughout your home.

Annual Fuel Utilization Efficiency (AFUE) Rating

When evaluating the energy efficiency of a new furnace, one of the most critical metrics to consider is the Annual Fuel Utilization Efficiency (AFUE) rating. The AFUE rating measures the percentage of fuel a furnace converts into usable heat for your home, compared to the amount lost during the combustion process and venting. Essentially, it indicates how efficiently a furnace uses its fuel.

The AFUE rating is expressed as a percentage, representing the ratio of the furnace's heat output to its total fuel consumption over a typical year. For instance, a furnace with an AFUE rating of 90% converts 90% of the fuel it consumes into heat, while the remaining 10% is lost through the flue or other means. The higher the AFUE rating, the more efficient the furnace, which translates to lower energy costs and less waste.

Comparison Between High and Low AFUE Ratings

Furnaces with high AFUE ratings are significantly more efficient than those with lower ratings. Modern furnaces typically have AFUE ratings ranging from 80% to 98.5%. In contrast, older furnaces, especially those installed before the 1990s, may have AFUE ratings as low as 60%. This discrepancy highlights the substantial improvements in furnace technology over the past few decades.

For example:

  • Low AFUE (60-70%): Older furnaces with these ratings waste 30-40% of the fuel they consume. These units are less efficient and more costly to operate.
  • Moderate AFUE (80-85%): These furnaces are more efficient, wasting only 15-20% of the fuel. They offer a better balance of cost and efficiency for many homeowners.
  • High AFUE (90% and above): The most efficient furnaces available today, with minimal fuel waste. These units provide significant energy savings and are ideal for those looking to maximize efficiency.

Benefits of Choosing a Furnace with an AFUE Rating of 80% or Higher

Opting for a furnace with an AFUE rating of 80% or higher offers several advantages:

  • Cost Savings: Higher efficiency means more of the fuel you pay for is converted into heat, reducing your monthly heating bills. Over time, the savings on energy costs can offset the initial investment in a more efficient furnace.
  • Environmental Impact: Efficient furnaces produce fewer greenhouse gas emissions, helping to reduce your home's carbon footprint. By consuming less fuel, these units also contribute to conserving natural resources.
  • Improved Comfort: High AFUE furnaces often come with advanced features such as modulating burners and variable-speed blowers, which enhance overall comfort by providing more consistent and even heating.
  • Enhanced Durability: High-efficiency furnaces are typically built with better components and materials, which can lead to a longer lifespan and fewer maintenance issues.

Two-Stage Heating

Two-stage heating refers to a furnace system that operates at two different levels of heat output: a lower, energy-saving mode for milder weather and a higher, full-capacity mode for colder temperatures.

Unlike single-stage furnaces, which operate at full capacity every time they run, two-stage furnaces can adjust their heat output based on the heating demands of your home. This capability allows the furnace to maintain a more consistent indoor temperature and provide a more comfortable living environment.

How Two-Stage Heating Improves Energy Efficiency

Two-stage heating enhances energy efficiency in several ways:

  • Reduced Fuel Consumption: By operating in a low setting most of the time, a two-stage furnace uses less fuel compared to a single-stage furnace that runs at full blast with every cycle. The lower setting consumes less energy, leading to significant cost savings over time.
  • Decreased Wear and Tear: The ability to run at a lower setting means the furnace doesn't have to cycle on and off as frequently. This reduces strain on the furnace's components, extending its lifespan and minimizing maintenance costs.
  • Consistent Temperature: Two-stage heating provides a more consistent and even temperature throughout your home. The furnace can maintain a steady heat output without the frequent temperature swings associated with single-stage systems. This consistent operation not only enhances comfort but also improves overall efficiency.
  • Improved Humidity Control: Two-stage furnaces often do a better job of controlling indoor humidity levels. By running at a lower speed for longer periods, they can remove more moisture from the air, which is particularly beneficial in humid climates.

Situations Where Two-Stage Heating Is Beneficial

Two-stage heating systems are especially advantageous in the following situations:

  • Variable Climate Conditions: Homes located in regions with fluctuating temperatures benefit greatly from two-stage heating. The ability to adjust heating output according to outdoor conditions ensures optimal energy usage and comfort regardless of the weather.
  • Large Homes: In larger homes, maintaining a consistent temperature can be challenging. Two-stage heating helps distribute heat more evenly throughout the house, preventing hot and cold spots and ensuring every room stays comfortable.
  • Homes with Zoning Systems: For homes equipped with zoning systems that control the temperature in different areas independently, two-stage furnaces offer better compatibility and performance. They can efficiently heat specific zones without wasting energy on unoccupied areas.
  • Energy-Conscious Homeowners: If reducing energy consumption and minimizing environmental impact are priorities, a two-stage heating system is an excellent choice. It offers substantial energy savings and reduces greenhouse gas emissions compared to single-stage systems.
  • Homes with High Insulation: In well-insulated homes, maintaining consistent temperatures can be more challenging with a single-stage furnace. A two-stage furnace can operate at a lower setting for longer periods, aligning with the home's insulation properties and enhancing overall efficiency.

Variable-Speed Blower

A variable-speed blower is a component in a furnace that can adjust its speed to match the heating needs of your home. Unlike traditional single-speed blowers that operate at a constant speed regardless of the heating demand, variable-speed blowers can run at different speeds. This adaptability allows the blower to provide a more precise and efficient airflow, enhancing the overall performance of the furnace.

Benefits of a Variable-Speed Blower

Energy Savings:

  • Variable-speed blowers consume less electricity because they can operate at lower speeds when full capacity is unnecessary. This reduced energy consumption translates to lower utility bills and significant cost savings over time.
  • By running at varying speeds, the blower can maintain a more consistent temperature in your home without the frequent on-and-off cycling typical of single-speed blowers. This reduces wear and tear on the furnace, extending its lifespan and lowering maintenance costs.
  • Since the blower can adjust its speed based on the heating demand, it only uses the energy necessary to maintain the desired temperature, optimizing the furnace's overall efficiency.

Indoor Air Quality:

  • Variable-speed blowers often run for longer periods at lower speeds, allowing the furnace's air filter to capture more airborne particles, dust, and allergens. This results in cleaner indoor air and a healthier living environment.
  • The ability to run at different speeds helps the blower remove excess moisture from the air more effectively, particularly during the cooling season. This improved humidity control can prevent mold growth and enhance comfort.
  • Variable-speed blowers provide a steady and even airflow, reducing drafts and hot or cold spots within the home. This consistent airflow contributes to a more comfortable and balanced indoor environment.

How a Variable-Speed Blower Adapts to Different Heating Needs

A variable-speed blower adapts to different heating needs by adjusting its speed based on real-time conditions and the specific requirements of your home:

  • Responsive Adjustment: The blower can respond to changes in the thermostat setting or outdoor temperature by increasing or decreasing its speed. For example, on a milder day, the blower may run at a lower speed to maintain comfort without wasting energy. On colder days, it can ramp up to provide more heat quickly.
  • Zoning Compatibility: In homes with zoning systems, the blower can adjust its speed to deliver the right amount of airflow to each zone, ensuring consistent temperatures throughout the house. This adaptability helps prevent energy waste and improves overall comfort.
  • Enhanced Comfort: The blower's ability to operate at different speeds allows it to maintain a more consistent indoor temperature. It avoids the abrupt temperature changes and noise associated with single-speed blowers, resulting in a quieter and more comfortable home environment.
  • Optimized Performance: By matching its speed to the heating demand, the variable-speed blower ensures that the furnace operates at peak efficiency. This optimization leads to better performance, reduced energy consumption, and a longer system lifespan.


The ENERGY STAR program is a government-backed initiative developed by the U.S. Environmental Protection Agency (EPA) to promote energy efficiency and reduce greenhouse gas emissions. Products that earn the ENERGY STAR label meet strict energy efficiency guidelines set by the EPA, which are based on rigorous testing and analysis.

The goal of the program is to help consumers identify and choose products that can save energy, save money, and protect the environment. Furnaces that carry the ENERGY STAR label are designed to be more energy efficient than standard models, providing significant benefits for homeowners.

Benefits of Choosing an ENERGY STAR Certified Furnace

  • Energy Efficiency: ENERGY STAR certified furnaces use advanced technology to achieve higher levels of energy efficiency compared to non-certified models. This means they convert more fuel into heat, reducing the amount of energy wasted. As a result, homeowners can expect lower energy bills and a reduced carbon footprint.
  • Environmental Impact: By choosing an ENERGY STAR certified furnace, you are contributing to environmental protection efforts. These furnaces produce fewer emissions, helping to reduce air pollution and combat climate change. The program's emphasis on energy efficiency supports sustainable practices and promotes a healthier planet.
  • Performance and Reliability: ENERGY STAR certified furnaces are designed to meet high standards of performance and reliability. They often include features such as variable-speed blowers and two-stage heating, which enhance comfort and ensure consistent temperatures throughout your home. These advanced features also contribute to the furnace's overall efficiency and longevity.
  • Enhanced Comfort: The technology used in ENERGY STAR certified furnaces provides better temperature control and improved indoor air quality. Features like variable-speed blowers ensure consistent airflow and reduce hot and cold spots, while advanced filtration systems help remove airborne particles, allergens, and moisture, leading to a healthier and more comfortable living environment.

Financial Incentives for Purchasing ENERGY STAR Furnaces

Purchasing an ENERGY STAR certified furnace can qualify you for various financial incentives, making the investment even more attractive:

  • Rebates: Many utility companies and local governments offer rebates to encourage homeowners to upgrade to energy-efficient appliances. These rebates can significantly offset the initial cost of purchasing an ENERGY STAR certified furnace.
  • Tax Credits: In some cases, federal and state governments provide tax credits for installing energy-efficient heating systems. These tax credits can reduce your taxable income, leading to substantial savings during tax season.
  • Long-Term Savings: While ENERGY STAR certified furnaces may have a higher upfront cost compared to standard models, the energy savings over the life of the furnace can be considerable. Lower monthly utility bills and reduced maintenance costs contribute to the long-term financial benefits of choosing an energy-efficient model.

To take advantage of these incentives, be sure to check with your local utility company and government websites for available programs and eligibility requirements. These financial benefits, combined with the energy savings and environmental advantages, make purchasing an ENERGY STAR certified furnace a smart and sustainable choice for any homeowner.

A Furnace’s Heat Exchanger

The heat exchanger is a critical component in any furnace, responsible for transferring heat from the combustion process to the air that circulates through your home. When fuel is burned in the furnace’s combustion chamber, it generates heat and exhaust gases. The heat exchanger absorbs this heat while keeping the exhaust gases separate, ensuring that only clean, heated air is blown into your living spaces.

This process not only warms your home efficiently but also prevents harmful combustion byproducts, such as carbon monoxide, from entering your indoor air.

Importance of High-Quality Materials for Heat Exchangers

Using high-quality materials for heat exchangers, such as stainless steel, is essential for several reasons:

  • Durability: Stainless steel is highly resistant to corrosion and rust, ensuring that the heat exchanger can withstand the high temperatures and moist conditions found in the combustion process. This resistance to corrosion extends the lifespan of the heat exchanger, making it a more reliable choice.
  • Thermal Efficiency: High-quality materials like stainless steel offer superior thermal conductivity, which means they can absorb and transfer heat more effectively. This efficiency improves the overall performance of the furnace, ensuring more of the fuel's energy is converted into usable heat.
  • Safety: A heat exchanger made from high-quality materials is less likely to crack or fail. Cracks in the heat exchanger can lead to dangerous situations where combustion gases, including carbon monoxide, could leak into your home. Using durable materials reduces this risk, ensuring a safer home environment.

Long-Term Benefits of a Durable Heat Exchanger

Investing in a furnace with a durable heat exchanger offers several long-term benefits:

  • Extended Lifespan: High-quality heat exchangers are designed to last longer, reducing the need for frequent replacements. This longevity means that your furnace will continue to operate efficiently and reliably for many years, providing consistent warmth to your home.
  • Lower Maintenance Costs: Durable heat exchangers require less maintenance and fewer repairs over time. This reduces the overall cost of ownership and minimizes the inconvenience of unexpected furnace breakdowns.
  • Energy Efficiency: A well-maintained, high-quality heat exchanger maintains its efficiency throughout its lifespan. This consistent performance ensures that your furnace uses less fuel to generate the same amount of heat, leading to lower energy bills and reduced environmental impact.
  • Enhanced Performance: Furnaces equipped with durable heat exchangers often come with advanced features that further improve energy efficiency and comfort. These features, combined with the reliability of a high-quality heat exchanger, ensure that your furnace performs optimally under various conditions.
  • Safety and Peace of Mind: Knowing that your furnace has a robust and durable heat exchanger provides peace of mind. You can be confident that your heating system is safe and effective, reducing the risk of hazardous gas leaks and ensuring a healthy indoor environment for your family.

Selecting the Right Size Furnace

Choosing the right size furnace for your home is crucial to ensure optimal performance, energy efficiency, and comfort. A properly sized furnace is tailored to meet the specific heating needs of your home, taking into account factors such as the size of the house, insulation levels, window efficiency, and climate.

Ensuring the furnace is neither too large nor too small is key to achieving maximum efficiency and maintaining a comfortable indoor environment.

Consequences of an Incorrectly Sized Furnace

Energy Inefficiency:

  • An oversized furnace will cycle on and off frequently, a process known as short cycling. This constant cycling uses more energy, resulting in higher utility bills. Additionally, it does not run long enough to reach its peak efficiency, leading to wasted fuel and increased operating costs.
  • An undersized furnace will struggle to maintain the desired temperature, running continuously without effectively heating the home. This overexertion leads to higher energy consumption and insufficient heating, making it difficult to achieve a comfortable indoor climate.

Increased Wear and Tear:

  • Frequent cycling on and off puts unnecessary strain on the furnace’s components, leading to premature wear and a higher likelihood of breakdowns. This can result in increased maintenance and repair costs and a shorter overall lifespan for the furnace.
  • Running constantly to try and heat the home, an undersized furnace can wear out quickly. The excessive demand placed on its components can cause frequent breakdowns and reduce the furnace’s lifespan, leading to higher long-term costs.

How to Determine the Correct Size with a Load Calculation

A load calculation is the most accurate method for determining the correct size furnace for your home. This calculation takes into account various factors that affect heating requirements, including:

  • Square Footage: The total area of the home that needs to be heated.
  • Insulation Levels: The quality and amount of insulation in the walls, attic, and floors.
  • Window Efficiency: The number, size, and type of windows, as well as their insulating properties.
  • Climate Zone: The local climate and typical outdoor temperatures.
  • Air Leakage: The amount of air that leaks into and out of the home through doors, windows, and other openings.
  • Occupancy and Lifestyle: The number of occupants and their heating preferences and habits.

Professional Load Calculation

To ensure accurate results, it’s recommended to have a professional HVAC contractor like The Boiler Shoppe perform the load calculation. The contractor will assess your home’s specific characteristics and input the data into specialized software to calculate the ideal furnace size. This ensures that the furnace will operate efficiently and effectively, providing consistent and reliable heating.

DIY Load Calculation

For homeowners interested in a rough estimate, there are online calculators available that can provide a basic idea of the required furnace size. However, these tools are less precise than a professional assessment and should be used with caution.

Sealed Combustion Chambers

In furnaces, the combustion chamber is where the fuel is burned to produce heat. The design of this chamber can significantly impact the furnace’s efficiency and overall performance. There are two main types of combustion chambers: open and sealed.

  • Open Combustion Chambers: These chambers draw air from the surrounding indoor environment to support the combustion process. While this design is simpler and less expensive, it has several drawbacks, including reduced efficiency and potential safety issues.
  • Sealed Combustion Chambers: In contrast, sealed combustion chambers draw air from outside the home through a dedicated intake pipe. This design isolates the combustion process from the indoor air, leading to several key advantages in terms of efficiency, safety, and indoor air quality.

How Sealed Combustion Chambers Improve Efficiency and Indoor Air Quality


  • By drawing air from outside, sealed combustion chambers ensure a consistent and adequate supply of oxygen for combustion. This consistency optimizes the combustion process, allowing the furnace to burn fuel more efficiently and generate more heat from the same amount of fuel.
  • Sealed combustion chambers minimize the heat loss that can occur when drawing air from inside the home. This containment ensures that more heat is directed into the living spaces, improving the furnace’s overall efficiency and reducing energy consumption.

Indoor Air Quality:

  • Since sealed combustion chambers are isolated from the indoor environment, harmful combustion byproducts, such as carbon monoxide and nitrogen dioxide, are kept out of the home. These gases are safely vented outside, significantly reducing the risk of indoor air pollution.
  • By preventing the influx of unconditioned outdoor air into the home, sealed combustion chambers help maintain more stable indoor humidity levels. This control contributes to a more comfortable and healthy living environment.

Additional Benefits Such as Improved Safety


  • Open combustion chambers can create negative pressure in the home, leading to backdrafting—a situation where combustion gases are drawn back into the house instead of being expelled outside. Sealed combustion chambers eliminate this risk by using dedicated intake and exhaust pipes, ensuring all combustion byproducts are safely vented outdoors.
  • Sealed combustion chambers reduce the likelihood of accidental fires. Since the combustion process is isolated from the indoor environment, there is less risk of flammable materials or fumes coming into contact with the burner flame.

Noise Reduction:

  • Sealed combustion systems often operate more quietly than open combustion systems. The sealed design contains the noise produced during the combustion process, resulting in a quieter overall operation that enhances indoor comfort.

Extended Furnace Lifespan:

  • Drawing combustion air from outside reduces the exposure of the furnace components to indoor dust and contaminants. This protection helps maintain the cleanliness of the furnace, reducing wear and tear and potentially extending the unit’s lifespan.

The Quality of the Installation

The quality of the installation is a crucial factor that directly impacts the performance, efficiency, and longevity of your furnace. Even the most advanced and high-quality furnace will not operate effectively if it is not installed correctly.

Professional installation ensures that the furnace is set up according to the manufacturer's specifications, local building codes, and industry best practices. This careful attention to detail is essential for the safe and efficient operation of the furnace.

Impact of Proper Installation on Furnace Performance and Longevity

Proper installation has a profound impact on the overall performance and longevity of your furnace:

  • Optimal Performance: A professionally installed furnace operates at peak efficiency, providing consistent and reliable heating throughout your home. Proper installation ensures that all components are correctly aligned, calibrated, and connected, which maximizes the furnace’s performance.
  • Energy Efficiency: Correct installation minimizes energy waste, ensuring that the furnace uses fuel efficiently. This not only reduces your energy bills but also lowers your carbon footprint. Improper installation, on the other hand, can lead to energy losses and higher operating costs.
  • Safety: Safety is a paramount concern when installing a furnace. Professional technicians ensure that all safety protocols are followed, including proper venting of combustion gases, secure electrical connections, and safe handling of fuel lines. This attention to safety reduces the risk of hazards such as carbon monoxide leaks and electrical fires.
  • Longevity: A furnace that is installed correctly is less likely to experience premature wear and tear. Proper installation helps prevent common issues such as poor airflow, improper combustion, and system strain, all of which can shorten the lifespan of the furnace. A well-installed furnace is more likely to provide reliable service for many years, reducing the need for costly repairs and replacements.
  • Warranty Protection: Many furnace manufacturers require professional installation as a condition of their warranty. Improper installation by an unqualified individual can void the warranty, leaving you responsible for any future repairs or replacements. Ensuring professional installation protects your investment and keeps the warranty intact.

Making the Smart Choice for Your Home's Heating

Investing in an energy-efficient furnace offers numerous long-term benefits. Beyond the immediate cost savings on energy bills, you gain the advantage of a more reliable and durable heating system. Improved indoor air quality, consistent comfort, and enhanced safety are additional perks that come with modern, efficient furnace models. Moreover, financial incentives like rebates and tax credits can further reduce the initial investment cost, making it an even more attractive option.

Selecting an energy-efficient furnace is a smart decision that pays dividends in both financial and environmental terms. By understanding and considering the factors that contribute to a furnace’s efficiency, you can make an informed choice that ensures comfort, savings, and sustainability for years to come.

Contact The Boiler Shoppe

Toronto & Area:
1255 The Queensway, Unit 11
Toronto, ON M8Z 1S1
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