What is a Dual-Fuel System?

A dual-fuel system is a home comfort system that pairs an electric heat pump with a gas furnace. As outdoor temperatures change, the system alternates between the two fuel sources, maximizing comfort and efficiency – offering the homeowner the key benefits of both fuel sources.

How a Dual-Fuel System Works

On its own, an electric heat pump is most efficient during warmer weather. As the temperature goes down during winter months, electric bills can rise as the pump has to work harder to heat the home. In a dual-fuel system, the heat pump works in conjunction with a gas furnace, which is more efficient in colder weather, to maximize the overall efficiency of the system.

During the summer months, the heat pump works like a high-efficiency central air conditioner. During mild spring and fall weather, it provides efficient, cost-effective heat. But as winter temperatures set in, the system shuts off the heat pump and lets the more effective furnace take over.

This temperature-based hand-off between the heat pump and furnace happens automatically based on the system’s settings, allowing homeowners to take advantage of the best of both worlds – electric and gas.

How does a dual-fuel system heat?

In the fall and spring when heating demands are lower, the system uses the more efficient heat pump to warm the air. This is because rather than using gas to generate heat, the heat pump uses a refrigerant cycle, pulling warmth from the mild outdoor air and transfers it indoors. This warm air is then distributed throughout the home by the electric air handler built into the furnace.

During the coldest days of the year, the system shuts off the heat pump completely and allows the gas furnace to ignite, more effectively meeting the higher heating demands brought on by the colder temperatures.

The outdoor temperature at which the system changes from electric heat to gas heat is variable and is selected during installation based on climate and the homeowner’s utility preferences.

How does a dual-fuel system cool?

During the warm summer months when the furnace is inactive, the refrigerant cycle within the heat pump is reversed. Heat is pulled from the air inside the home and transferred outside, lowering the indoor temperature.

Benefits of a Dual-Fuel System

Though a dual-fuel system isn’t always the right answer, there are significant benefits to installing one under the right conditions.

  • Increased Energy Efficiency

A dual-fuel system optimizes energy use by automatically switching between electric and gas fuel sources. Whatever the outdoor condition, it will opt for the more efficient of the two heating options. When it’s cool outside during fall and spring, the electric heat pump provides the most efficient, cost-effective heating method. On the coldest days of those days, based on the settings your installer programmed into the system, the gas furnace is ignited allowing it to handle the heavier heating requirements of those days. This switching cycle can be tailored to most any climate. Your installer can help you decide the optimum temperature cycle for your home.

Heat pumps also save energy because it’s more efficient to transfer heat than it is to create it. Surprisingly, even when it feels cold outside, there’s still enough heat captured from the outdoor air to make the heat pump the most efficient option. In fact, under ideal conditions, a heat pump can transfer upwards of 300 percent more energy than it consumes. By contrast, high-efficiency gas furnaces are about 90-percent efficient (although, it is worth noting that top-of-the-line furnaces can be up to 99-percent efficient).

  • Cost Savings

While dual-fuel systems call for a greater initial investment than conventional systems, those costs are easily offset by the efficiency of the system. By prioritizing the heat pump (except in the most high-demand situations), the system can run on electricity a majority of the time. Since in many markets gas is more expensive to use than electricity, the savings can add up quickly.

However, because utility costs can vary by location, proper setup is critical to seeing these savings. If you happen to live in an area where electricity costs are higher than gas, your system should be tuned to take advantage of that – activating the furnace sooner than in a typical heat pump-dominated system.

  • Flexibility

Directly related to cost savings is the inherent flexibility of dual-fuel systems. The ability to fine tune your system to your weather, region, and utility costs lets you, the homeowner, take advantage of the most cost-effective fuel source for your specific circumstance. 

  • Quiet Operation

No matter the specific model you choose, all the components of a Lennox dual-fuel system are engineered to maximize efficiency while minimizing noise levels. Whether you’re cooling your home during a scorching summer or heating it during extreme winter temperatures, both the heat pump and furnace are optimized for quiet operation. Our higher efficiency systems are some of the quietest in the industry, utilizing technology like SilentComfort to reduce system noise even further.

  • Reduced Environmental Impact and Carbon Footprint

Since most systems operate using electricity instead of gas upwards of 85 percent of the time, a dual-fuel system is an environmentally responsible option. While typical gas furnaces get an AFUE rating of between 80-90% efficiency, they burn gas - which naturally generates by-products that can affect the environment. Electric heat pumps are often more than 100% efficient and create no harmful by-products.

Available Tax Benefits

In addition to efficiency and performance benefits, all of which can translate to savings on your heating and cooling bill, dual-fuel systems can qualify you for tax benefits and rebates in many markets. 

  • Federal HVAC Tax Credits

Opting for a high-efficiency Lennox dual-fuel system may allow you to take advantage of multiple federal, eco-friendly tax credits, saving you up to $2,600 on your system. If your system qualifies, you may be eligible to receive a credit on your next tax return. This can be done by simply downloading the corresponding form and claiming the purchase on your taxes. Along with other qualifying factors, eligibility requires the equipment be installed in your primary residence.

Visit the energystar.gov site to learn more about these and other current U.S. tax credit opportunities.

  • Local Utility Rebates

There’s also a chance to save hundreds more on your high-efficiency heating and cooling system through rebates offered by your local energy provider. Actual savings will vary based on your provider and where you live. To find out more visit our rebate center, ask your Lennox Dealer, or contact your local utility provider.

Is Installation and Maintenance on Dual-Fuel More Complicated than a Conventional HVAC System?

Though on paper a dual-fuel system may seem more complex than other conventional solutions, installation and maintenance follow the same processes and requirements as a traditional single-fuel system.

As with any HVAC system, regular DIY maintenance such as cleaning vents and replacing filters goes a long way to keeping your system healthy. In addition, as with conventional systems, annual tune-ups by a licensed technician are recommended, beginning with a follow-up diagnostic and tune-up performed soon after your system is installed to ensure everything is performing as expected. Read more about the importance of seasonal preventative maintenance and annual tune-ups performed by a Lennox pro.

How Do I Know if a Dual-Fuel System is Right for Me?

There are certain environmental and regulatory conditions that can make a dual-fuel system a better option than a conventional HVAC setup.

Does your home experience all four seasons?

First and foremost, dual-fuel systems provide the most benefit in regions that experience yearly temperature fluctuations – with colder winters, warmer summers, and mild, recognizable spring and fall seasons. It may sound like any system would need to work harder in this kind of environment, but these ranges in temperature ensure both sides of the dual-fuel system are being used where they perform best, optimizing the system’s efficiency overall.

The nature of a dual-fuel system is to optimize the operating efficiency of the system as needed based on seasonal temperature fluctuations. Installing a dual-fuel system in a predominantly cool-to-cold environment where a furnace is more effective, will negate the warm weather benefits that a heat pump can provide. In regions that are typically mild or warmer year-round, a heat pump alone should be able to handle your heating and cooling needs. Though a dual-fuel system can handle most any climate, installing one where it isn’t optimal can affect the intended cost-saving balance between electric and gas – and make recouping your initial investment difficult.

Do your local regulations encourage efficiency?

Several states have begun passing environmentally friendly laws that encourage and reward their residents for purchasing more energy-efficient products. HVAC equipment, especially heat pumps, weigh heavily in many of these new regulations. Heat pumps are favored because the process they use to generate heat relies on a transfer of energy rather than its creation through less environmentally friendly processes like the burning of natural gas or propane. If you live in an area that encourages energy-efficient HVAC equipment, use the energy efficiency rating of the equipment you’re considering to see if you qualify for local tax breaks or other incentives.

Are you looking to reduce sky-high utility bills?

If you live in an area where historically the cost of one utility or the other (electricity or gas) is particularly high or low, a dual-fuel system can give you the flexibility to tighten your overall utility expenses. Along with the fuel-switching technology that already makes dual-fuel a more effective and efficient solution, your installation technician can work with you to customize your system’s settings to make the best use of your electric and gas options.

Though dual-fuel systems aren’t always the ideal solution, there can be significant benefits to installing one in the right home. A high-efficiency Lennox dual-fuel system can not only provide you with quiet, consistent comfort - it can help you save money, reduce your carbon footprint, and even earn you a few tax perks if you qualify.

Connect with your local Lennox dealer today to discuss whether a dual-fuel system is an appropriate option for your home.

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