Switch Hitters

Dual fuel configurations allow customers to adapt to changing temperatures and fuel prices, granting them the ability to alternate power or fuel sources. Much like other advanced electric technologies, many dual fuel heat pumps can be programmed to optimize economic or environmental impacts according to a homeowner’s utility goals.

“For homeowners in colder climates who want to reduce their carbon footprint and their utility bills, but whose heating demands can sometimes exceed heat pump capacity, dual fuel heat pump systems will often be the right solution,” said Mark Lessans, senior director, sustainability and regulatory affairs, global sustainability, Johnson Controls. “Dual fuel systems are extremely energy-efficient — reducing site energy use by as much as two-thirds when the heat pump is operational while also eliminating the use of inefficient electric resistance backup heating.”

Electric systems produce zero carbon emissions, making them environmentally friendly. Adding a heat pump to a gas system provides homeowners protection from rising gas prices and protection during extreme weather conditions.

“There is a negative perception that heat pumps do not work in cold climates, so the presence of a gas furnace in the system provides homeowners with the confidence that their system will reliably keep them warm,” said Cameron Prince, senior product marketing manager, residential split systems, Allied Air Enterprises. “Installing a heat pump with a gas furnace is a way to provide multiple sources of heat to overcome technology limitations.”

As consumers navigate the transition to electrification and a more sustainable energy landscape, dual-fuel heat pump units are positioned as reliable, forward-looking solutions.

“The ability to combine gas and electric heating methods aligns with the broader push for environmentally friendly alternatives, making dual-fuel units a significant step in this transition,” said Tim Brizendine, director of product management, Lennox. “The ability to switch between energy sources, in addition to their smooth integration of advanced controls and smart features, positions dual fuel heat pumps well for the changing landscape of energy production and consumption.”

Environmental Efficiency

More than 440 million tons of carbon emissions are produced each year from heating and air conditioning homes alone, according to the Center for Climate Change and Energy Solutions. Dual fuel solutions are a natural step toward making homes and other buildings cleaner and more sustainable while simultaneously cutting energy-usage costs.

“Dual fuel systems that include all-climate, variable-capacity heat pumps are more environmentally friendly than conventional HVAC systems,” said Chris North, program manager, residential product marketing, Mitsubishi Electric Trane HVAC US LLC (METUS). “Heat pump systems produce less carbon emissions than their conventional counterparts because they’re fossil-fuel-free and consume less electricity.”

Whereas a traditional a/c and furnace system utilizes gas for 100% of the heating, a dual fuel system can alternate the primary heating source from gas to electricity.

“With a dual-fuel system, the heat pump will provide all-electric heat pump heating for most of the year,” said King Tong, heat pump portfolio leader, Daikin Comfort Technologies. “During times when homes may require more heating, such as a severe cold front, the heating source can switch to the gas furnace. A dual-fuel system decreases emissions versus a furnace-only application by about 10%.”

Along the path to decarbonization and electrification, dual-fuel heat pump technology is being explored as an enabling, eco-friendly alternative capable of bridging the gap between today and tomorrow’s HVAC install base.

“Dual-fuel heat pump technology relies on a combination of electric heat pumps and fossil fuel-based furnace technologies, similar to hybrid vehicles prevalent in today’s automotive industry,” said Eric Strausbaugh, director, product marketing, residential, Copeland. “Electric heat pump adoption is widely considered one of the most impactful HVAC equipment choices for helping enable the long-term decarbonization of residential HVAC footprints.”

Economic Efficiency

There are many federal, state, and local incentives available that encourage heat pump adoption and significantly reduce the upfront costs of dual fuel heat pump systems. For instance, the Inflation Reduction Act (IRA) expanded incentives for high-efficiency HVAC equipment, including the 25C tax credit.

Under the revised tax credit, homeowners can receive a $2,000 incentive for high-efficiency heat pumps and $600 for high-efficiency furnaces.

“Dual fuel heat pump systems are currently eligible for up to $2,600 in federal tax credits,” said Lessans. “Additionally, many electric utilities offer incentives for customers to install high-efficiency heat pumps, and these incentives can usually be combined with federal and state programs. Climate policies and incentive programs differ from state to state and even city to city, so rebate amounts and qualifications may change depending on location.”

Despite the rebates and economic and environmental benefits these systems afford, awareness among the general population remains fairly low.

The 2023 Heat Pump & Homeowners Index, a survey created by METUS to explore American homeowners’ knowledge of and attitudes toward the IRA and the move toward clean energy, revealed that while 63% of the 1,000-plus survey respondents have heard about the landmark legislation, 64% have little knowledge of heat pumps.

“This shows we have a way to go toward educating consumers on the benefits of heat pumps, including their ability to heat and cool homes, regardless of outdoor temperature, their energy efficiency, ability to reduce utility bills, and sustainability,” said North. “The good news is that a separate segmentation study we conducted shows that younger buyers have much more awareness of dual fuel systems — twice as much as previous generations.”

Now Available

HVAC manufacturers offer an assortment of dual fuel options, ranging in size and efficiency.

COMPATIBILITY: Allied Air’s latest offering, the 4SHP22LX, is an Energy Star Most Efficient inverter heat pump that can be matched with a gas furnace to help provide even, consistent comfort. (Courtesy of Allied Air Enterprises)

Allied Air Enterprises’ array of heat pumps are well suited for dual fuel systems. The company’s latest offering, the 4SHP22LX, is an Energy Star Most Efficient inverter heat pump that can be matched with a gas furnace to help provide even, consistent comfort.

“The 22LX can be paired with our communicating Comfort Sync A3 thermostat or connected to a traditional 24V thermostat,” said Prince. “When paired with the Comfort Sync A3, contractors can save time at installation with the auto-commissioning capabilities of this thermostat and the fact that only four wires are required for installation. The A3 will recognize what type of equipment is connected, meaning no additional controls are needed for a dual fuel system.”

Lennox’s SL25XPV integrates a heat pump, a smart thermostat, and a gas-powered furnace, ensuring optimal energy usage and cost-effectiveness.

“This unit’s ability to switch seamlessly between the two heat sources — depending on external factors, like weather conditions and energy costs — makes it a precise and efficient heat pump option,” said Brizendine. “The variable-capacity unit is nationally recognized as one of the most efficient Energy Star-certified products for reducing greenhouse gas emissions and meeting rigorous energy efficiency levels set by the EPA.”

Johnson Controls’ York YZV 19 SEER2 Variable Capacity Heat Pump adjusts capacity and airflow to precisely match a home’s changing comfort needs while providing reliable performance. When paired with a York furnace, such as the York YP9C 98% Modulating Gas Furnace, it can operate as a complete, high-efficiency dual fuel system.

“This Energy Star Most Efficient system enables space heating that optimizes for a lower carbon footprint,” said Lessans. “Contractors that have an understanding of a home’s heating load, heat pump operating conditions, utility rates, and available incentives will be well-positioned to sell dual fuel heat pump systems.”

Mitsubishi Electric’s intelli-Heat Dual Fuel Heat Pump system, which was introduced earlier this year, consists of an exterior heat pump replacing an existing air conditioning condenser and an interior unit installed on a customer’s existing furnace.

“Intelli-Heat helps homeowners achieve a more electrified, sustainably built environment by seamlessly integrating heat pumps with gas furnaces and reducing fossil fuel usage,” said North. “This solution is compatible with most thermostatically controlled gas furnaces and works with both single- and multizone systems. Furnaces remain available to the homeowner as a backup heating source for extreme cold conditions, but when the furnace is not needed, intelli-Heat runs and burns no gas. This system reduces greenhouse gas emissions inside homes.”

COMPATIBILITY: Mitsubishi Electric’s intelli-HEAT™ Dual Fuel Heat Pump system is compatible with most thermostatically controlled gas furnaces and works with both single-zone and multi-zone systems. (Courtesy of METUS)

INTELLI-HEAT: Mitsubishi Electric’s intelli-HEAT™ Dual Fuel Heat Pump system consists of an exterior heat pump replacing an existing air conditioning condenser and an interior unit installed on a customer’s existing furnace. (Courtesy of METUS)

In addition to providing homeowners with a system less dependent on fossil fuel, intelli-Heat also saves on product and installation costs because a homeowner can keep their existing furnace, said North.

“Many furnaces can outlast conventional air conditioners, so when it’s time to replace an air conditioner, or there’s simply a desire to upgrade to an efficient heat pump system, the homeowner can connect intelli-Heat with their furnace,” he continued. “This choice can be less expensive for homeowners than installing a full heat pump system.”

Whether it’s a single-stage or an inverter system, Daikin has dual fuel heat pump matchups for all of its product families.

“We recently completed our dual-fuel offering for our Daikin Fit platform with the introduction of new coils,” said Tong. “These coils are designed with our award-winning heat exchanger technology and equipped with a factory-installed EEV that allows for precise electronic refrigerant control, both contributing to the overall system energy efficiency.”

Inverter-driven dual fuel systems are designed to provide homeowners optimal comfort and efficiency at all times.

“The Daikin Fit connects to one of Daikin’s intuitive communicating thermostats, so as we continue to enhance the operation of the units, we can provide over-the-air system updates seamlessly today and in years to come,” said David Palazzolo, air conditioning portfolio leader, Daikin Comfort Technologies.

MULTIPLE CONFIGURATIONS: Daikin’s VRV LIFE system may be used in multiple ways, as shown here. (Courtesy of Daikin)

Copeland’s various types and configurations of fixed-speed (ZPK7), two-stage (ZPSK7), and variable-speed (ZPV2) compressors — including those with enhanced vapor injection (EVI), which enables a significant system capacity boost for the most challenging heating requirements — all serve as catalysts in the industry’s quest to address society’s next-generation of heat pump challenges.

“Copeland scroll fixed-speed compressors are already used in many warm-climate residential heat pump applications,” said Strausbaugh. The increased heating efficiency of the fixed-speed compressor enables improved performance in residential and commercial applications, including dual fuel applications.

“Copeland also offers variable-speed compressors that will support the deployment of cold climate heat pumps [CCHPs] for lower ambient conditions,” added Strausbaugh. “Additional offerings include Copeland’s two-stage compressor, which gives systems the ability to adjust capacity to match the heating load, resulting in longer run times at higher efficiency.”

A Transitional Strategy

Dual fuel heat pumps are highly flexible systems designed to meet customers’ needs by providing comfort as efficiently as possible. As customers aim to wean themselves off of fossil fuel, dual fuel heat pumps have emerged as an ample option.

“Dual fuel heat pumps are critical for grid reliability and decarbonization as the nation transitions toward a more diversified and clean energy system,” said Lessans. “Embracing dual fuel heat pumps as part of a transitional electrification strategy can help our entire country overcome these significant barriers.”