ECO Hybrid System

What the Plumbing & Mechanical Product of the Year Ranking Means

Each year, Plumbing & Mechanical publishes its Top 20 Products of the Year, based entirely on real‑time reader engagement. Products are ranked by what contractors, engineers, and facility professionals are actively clicking, researching, and bookmarking on pmmag.com.

Because the list is driven by website pageviews—not editorial opinion—it serves as a real‑world snapshot of the technologies and products gaining traction across the plumbing and HVAC industry. The ECO Hybrid System earning the #1 position highlights growing demand for solutions that support today’s jobsites while preparing for future specifications and customer expectations.

Why Hybrid Hydronic Systems Are Gaining Momentum

Hybrid heating systems are increasingly viewed as a practical path forward for residential applications. By pairing an air‑source heat pump with a high‑efficiency boiler, hybrid hydronic systems offer:

• Fuel flexibility to adapt to energy availability and operating costs
• High efficiency performance across a wide range of outdoor conditions
• Compatibility with existing hydronic distribution systems, making them well suited for retrofits
• A bridge toward electrification, without sacrificing reliable heating in cold climates

These advantages are driving increased interest among HVAC contractors navigating changing energy policies and regional utility considerations.

Inside the ECO Hybrid System

The Weil‑McLain ECO Hybrid System integrates the ECO HP outdoor heat pump with an indoor heat‑integrating unit and a Weil‑McLain boiler to deliver a coordinated hybrid hydronic solution. The system is designed to optimize performance automatically by leveraging the most efficient heat source, depending on operating conditions.

Key benefits of the ECO Hybrid System include:

• Seamless integration with hydronic heating systems
• Flexible fuel operation to support regional energy needs
• Simplified system configuration and operation
• New opportunities for contractors installing hybrid heating solutions today

Positioned for the Next Wave of Heating Expectations

As specifications and homeowner priorities continue to evolve, hybrid systems are emerging as a viable solution that balances efficiency, performance, and flexibility. The ECO Hybrid System’s #1 ranking reinforces its position as a technology that aligns with where the industry is headed.

Weil‑McLain is proud to see the ECO Hybrid System recognized by the Plumbing & Mechanical audience. We remain committed to supporting contractors with hydronic solutions designed for today and tomorrow. Contact us to find out more.

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Weil-McLain boilers are designed to operate with specific combustion components and control settings based on fuel type. This is critical because propane and natural gas differ significantly in energy content and pressure requirements.

Propane contains approximately 2,500 BTUs per cubic foot, compared to 1,000 BTUs per cubic foot for natural gas. As a result, propane systems require less fuel flow to achieve the same heat output but operate at higher incoming gas pressures. Without the proper configuration, improper combustion, reduced efficiency, or equipment damage can occur.

To account for these differences, propane-fired boilers typically use orifice restrictions to limit gas flow and, in some high-efficiency models, a dedicated propane venturi to maintain correct air-to-fuel ratios.

Most Weil-McLain boilers ship factory-set for natural gas and must be converted to propane in the field using an approved propane boiler conversion kit. The following models are available from the factory in propane and do not require conversion:

• Ultra (80)
• CGi
• CGa

All other applicable models require conversion per the instructions included with the kit and the boiler manual.

Natural Gas to Propane Conversion: Installation Best Practices

When performing a natural gas to propane boiler conversion, follow these steps carefully:

• Verify all components listed on the conversion kit packing sheet are included
• Install every component in the conversion kit—do not omit parts
• For cast iron boilers, confirm the control module is propane compatible
• Apply all propane conversion labels included with the kit
• Update the control module to Propane or LP before firing, where applicable

Ultra boilers (except size 80) ship with a propane orifice and gas conversion label. Store these with the boiler for future use if needed.

Where required, complete all coarse gas valve adjustments outlined in the conversion instructions and boiler manual before firing. Failure to complete pre-adjustments may result in damage to the boiler.

Verify gas pressure with the boiler running:

• Natural Gas: ≥ 3.5” WC
• Propane (LP): ≥ 10.0” WC
  • Do not exceed 14” WC static pressure, as this can damage the gas valve

Using a combustion analyzer, set combustion values strictly according to manual specifications.

Failure to follow the conversion instructions and boiler manual can lead to improper combustion and unsafe operating conditions. You are working with flammable gases—improper installation may result in property damage, serious injury, or even loss of life.

Need a Propane Conversion Kit?

Propane conversion kits are available through authorized Weil-McLain distributors. Click here to find a distributor.

For full installation instructions and model-specific requirements, reference our Resource Library or specific boiler product page on weil-mclain.com. Also, check out our training videos that walk through the process with a few select boiler models.

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When the temperatures drop and boilers start firing up for the season, it’s the perfect time to make sure your heating system is ready for the months ahead. A well-maintained boiler not only keeps your home comfortable but also helps ensure efficient performance and long-term reliability.

Here’s a simple checklist to help get your boiler winter ready:

• Check system pressure – Make sure your boiler pressure is within the recommended range.
• Watch for leaks – Look around valves, pumps, and radiators for any signs of water.
• Inspect the flue gas venting system – Check for blockages, leakage at joints, or deterioration in the piping.
• Test the thermostat – Confirm it’s working properly and set to the right temperature.
• Inspect the carbon monoxide detector – Replace the batteries and make sure it’s functioning.
• Schedule annual maintenance – Have a qualified pro inspect and service the system.

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A Contractor’s Perspective on Delivering Comfort, Savings with Hybrid Heat Pump System

When a homeowner in the Chicagoland area wanted to improve energy efficiency and lower propane heating costs, contractor James Downs of JMD Associates recommended an innovative solution: the ECO Hybrid Dual Fuel Hydronic System from Weil-McLain. Installed in a 20-year-old home near Lake Michigan, the system combines an air-to-water heat pump with a high efficiency gas boiler to deliver optimal performance and flexibility across a wide range of temperatures.

A Home Ready for Hybrid

The home featured an existing hydronic radiant floor heating system, as well as a snow melt system for the driveway and sidewalk, which were powered by a propane-fired high-efficiency Weil-McLain boiler. Downs described the property as an ideal candidate for a hybrid installation due to its low temperature heating setup and the homeowner’s desire for greater sustainability and cost control. The homeowner was motivated not only by rising fuel costs, but by a desire to make more climate conscious decisions and maximize efficiency with their existing radiant system.

“The boiler only kicks in when needed – striking a smart balance between performance and comfort”

“With radiant floor heating already in place in the home and the climate conditions in the Chicagoland area, this was a great opportunity for a hybrid setup,” said Downs. “The heat pump is designed to handle most of the heating season efficiently, and the boiler only kicks in when needed – striking a smart balance between performance and comfort.” The chosen solution featured a Weil-McLain ECO Hybrid System, which included an outdoor air-to-water heat pump and a compact indoor wall-mounted unit, both designed to work with the existing high-efficiency modulating propane boiler.

The ECO HP is designed to integrate seamlessly with Weil-McLain’s high-efficiency condensing boilers. By combining a durable, inverter-driven outdoor heat pump with a compact indoor unit, the system intelligently shares the heating load – maximizing energy efficiency and minimizing fuel consumption. It features intuitive user interface, integrated staging control capabilities and compatibility with indirect water heaters. Ideal for residential applications using radiant floor heating or low-temperature hydronic systems, the ECO HP delivers quiet operation, long-term reliability and measurable reductions in energy costs. In this case, the outdoor unit was mounted on a stand to prevent snow accumulation and ensure proper drainage – an important consideration in Lake Michigan’s lake-effect climate.

As a bonus for the home’s domestic hot water needs, an indirect tank was integrated into the system, while a dedicated heat exchanger handled the snow melt functionality for exterior surfaces. Heating throughout the residence was divided into six zones, each managed through a centralized zone control panel for efficient distribution.

Smooth Installation and Reliable Performance

According to Downs, the installation was straightforward and similar to setting up a conventional central air system. “The indoor unit was lightweight and compact – easy to mount with standard tools,” he said. “The outdoor unit connected via flare fittings, and the line set was within the range for the unit’s pre-charge, so everything aligned perfectly.” The 120V indoor unit and 240V outdoor unit required standard connections. Controls were intuitive, and the system relied on Weil-McLain’s guidelines to set compressor runtime limits and optimize switchover from the heat pump to the boiler. Downs noted that while the system was new, the manual was easy to follow.

“If you’re already doing mini-splits and hydronics, this is very manageable,” he said.

The installer also credited Weil-McLain’s ECO Calc Application Sizing Tool, which guided setup of system parameters and switchover logic. For this application, the hybrid system is designed to allow the heat pump to meet demand down to approximately 15°F. In colder conditions or during long domestic hot water calls, the boiler supplements the heat pump without shutting it down, maintaining comfort while maximizing efficiency. In this installation, a 30-minute runtime threshold on the compressor triggers the boiler, ensuring fast response without sacrificing energy savings.

Downs reported approximately $600 in propane savings in the first season alone. “The propane deliveries noticeably dropped,” he noted. “That, combined with stable indoor temperatures
and quieter operation, made it a win for the homeowner.”

Comfort remained consistent with no cold spots. Domestic hot water is stored at 140°F and tempered with a mixing valve for safe delivery, providing reliable service even during peak use.

A Thoughtful Investment

While the upfront investment for hybrid systems can be higher than traditional replacements, the propane fuel source made the business case compelling. Downs believes additional savings will become evident over time, especially as rebates become more accessible.

“This was about reducing environmental impact and operating costs. With the heat pump carrying the load for much of the year, that’s exactly what we achieved,” he added.

Downs views the ECO Hybrid System as an ideal choice for this low-temperature hydronic application. “The ECO Hybrid is a really smart upgrade as long as you evaluate the heat emitters and understand your reset curves,” he said. It’s not a one-size-fits-all solution, but if you’re working with radiant floors or low-temp baseboards and looking to cut fuel costs, especially with propane, it’s a great fit.”

Zachary Golden, Product Manager with Weil-McLain, added: “This installation is a prime example of how a well-matched hybrid system can deliver real value. With contractors like James leading the way, we’re seeing high-efficiency systems work smarter for homeowners.”

The hybrid installation offers long-term benefits in efficiency, comfort and performance – making it a model for future heating system upgrades in cold climates.

To learn more about Weil-McLain’s ECO Hybrid System or to speak with an expert about emerging residential heating technologies, visit weil-mclain.com/contact-us. Click here to download the full case study.

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A B100 compatible boiler is one that operates with a fuel blend consisting of 100% biodiesel. Biodiesel is a renewable fuel made from organic materials such as plant and vegetable oils, animal fats and used cooking oils.

“Weil-McLain boilers that are B100 certified are designed to operate on this blend of biodiesel fuel with the approved Beckett and Carlin burners,” said Mike Boyd, product manager with Weil-McLain. “These compatible burners have seals and components designed to optimize operation when using biodiesel.”  

Climate Conscious Solutions

Using B100 with a certified oil boiler can help reduce greenhouse gas emissions because biodiesel is a cleaner-burning fuel than petroleum diesel that can provide similar performance while significantly limiting how much carbon dioxide is released into the air. Other benefits of using a B100 certified boiler include:  

• Renewable energy source: Biodiesel is made from renewable sources, meaning it can be continually produced by a steady supply of raw materials. By utilizing biodiesel in a B100 blend, the dependence on finite fossil fuel resources can be reduced. 
• Energy security: Incorporating biodiesel into a fuel mix diversifies energy sources and reduces dependence on foreign oils and petroleum. This can contribute to enhancing energy security and reducing vulnerability to supply disruptions.
• Government incentives: In some regions, there may be government incentives, grants or tax credits available for using biodiesel.  

In addition to these benefits, homeowners interested in upgrading to one of these units can reap the rewards of a federal tax credit. Weil-McLain is a Qualified Manufacturer (QM), and its residential oil water boilers with an 87% AFUE rating installed between January 1, 2025, and December 31, 2025, can be claimed for up to $600 after meeting federal requirements. Eligible homeowners must include the four-digit QM code of “46H2” when completing their taxes for 2025 using tax form IRS Form 5695, Residential Energy Credits (the QM code may be used in lieu of a product identification number (PIN)). This tax credit can also be used in conjunction with any local ENERGY STAR^® rebate programs. 

Versatile Applications

Weil-McLain’s oil-fired boilers are an ideal solution for residential applications. Available for both water and steam systems, these high-efficiency units are rugged and reliable – providing peace of mind comfort heating for years to come. And with AFUE ratings of 85% to 87%, they all can significantly reduce energy waste while providing fuel cost savings. The Ultra Oil is the industry’s premium “commercial-grade” residential boiler featuring an easy-to-clean, three-pass heat exchanger. The WTGO is the perfect boiler for customers seeking an “all-in-one” space and domestic hot water heating appliance, while the SGO (steam) and WGO (water) are great for easy inspection and service due to their quick-open tops and swing-away burner doors that provide full chamber access.

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About Weil-McLain

Weil-McLain^® is a leading North American brand of hydronic comfort heating systems for residential, commercial, and institutional buildings since 1881. Known for innovation and reliability, Weil-McLain is committed to delivering high-efficiency heating solutions that prioritize comfort, energy savings, and sustainability. Weil-McLain continues to serve as a trusted partner by providing Solutions that Matter for the diverse needs of contractors, engineers, architects, homeowners, and facility managers, where products are trusted in homes, offices, schools, restaurants, hotels, and more throughout North America.

WM Technologies, LLC, assembles, sells, and distributes Weil-McLain boilers from Eden, North Carolina, and manufacturers cast iron products in Michigan City, Indiana, with approximately 600 employees across manufacturing facilities, sales locations, and administrative offices in Burr Ridge, Illinois. Backed by the global strength of SPX Technologies Inc, WM Technologies, LLC is dedicated to driving industry innovation and advancing climate-conscious heating solutions. For more information, visit www.weil-mclain.com.

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Weil-McLain is excited to announce the launch of its 2025 Contractor Promotion – Home Field Advantage. Running from September 1 through December 31, 2025, the program gives Advantage contractors the chance to rack up rewards and even earn a free boiler by installing Weil-McLain’s high-efficiency products.

The play is simple: contractors who register 12 qualifying high-efficiency boilers during the promotion period will receive a free Simplicity Combi Boiler—with their choice of 110, 150, or 199 MBH models. On top of that, Advantage points are going into overdrive with 5X points on every Simplicity registration and 2X points on all other high-efficiency models. Points can be redeemed anytime for rewards like gift cards, electronics, luggage, and more. Elite members can also use points for Market Development Funds to grow business exposure.

Not yet part of the Weil-McLain Advantage Program? There’s still time to get in the game. Contractors who join gain access to exclusive promotions like this, along with valuable business-building tools such as on-demand training and homeowner leads.

The 2025 heating season is here—don’t wait for the final whistle. Make every install count with Weil-McLain’s Home Field Advantage promotion.

Learn more and get started today: Weil-McLain.com/promotions

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Burr Ridge, Ill. – August 18, 2025 – Weil-McLain^®, manufactured by WM Technologies, LLC, a leading North American designer of hydronic heating systems, is advancing its bold rebranding initiative with the launch of a new brand campaign: “One Brand. Every Application. Only Weil-McLain.” This campaign marks the next step in the company’s evolution, building on its updated visual identity introduced earlier this year and reinforcing its future-forward commitment to innovation, energy efficiency and system-wide versatility.

With this new campaign, Weil-McLain is underscoring its position as a comprehensive provider of hydronic heating solutions, as well as showing its ongoing dedication to delivering future-forward sustainable innovations. The campaign was designed in response to the challenges today’s contractors face – balancing tight timelines, changing regulations and diverse system requirements across residential, commercial and institutional environments. From cast iron boilers and high-efficiency condensing units to hybrid systems with next-generation heat pumps, Weil-McLain delivers unmatched variety, flexibility, and performance that contractors need on the job.

“Our brand campaign captures the strengths of who we are today and demonstrates the dedication and commitment to where we’re going,” said Mike Doorhy, Vice President and General Manager of WM Technologies, LLC. “Weil-McLain is leading the charge in modern hydronics – providing contractor-friendly, sustainable heating solutions for every application.

Rooted in a legacy of quality and reliability, the “One Brand. Every Application.” campaign signals more than a refreshed look – it’s a renewed promise to the industry. Backed by a robust portfolio of training, technical support and intuitive tools, Weil-McLain is uniquely positioned to help professionals specify, install and maintain the right system – quickly, confidently and cost-effectively.

New Website Experience Brings the Brand to Life

As a cornerstone of the campaign, Weil-McLain has also launched an all-new website designed to deliver an intuitive, personalized experience for contractors, engineers, distributors and homeowners. The website reflects the brand’s updated visual identity and provides faster, easier access to key tools, technical resources and product information, all presented with modern visuals and clean layouts.

Key enhancements include:

• Mega Menus and Streamlined Navigation: A simplified interface provides quick, intuitive access to products, support, and training content.
• Expanded Resource Hub: A centralized section features technical documentation, training materials, and support tools.
• Enhanced Search: Improved functionality surfaces full-page content and technical materials more efficiently.

With more than 140 years of heating leadership, Weil-McLain continues to evolve while remaining rooted in the trust and performance professionals rely on. The new campaign and digital tools reaffirm the company’s long-standing commitment to innovation, accessibility and complete hydronic solutions – delivered by one brand, for every application.

Together, the new brand messaging and digital platform demonstrate Weil-McLain’s continued investment in product innovation, user experience and the future of hydronic heating.

Explore the refreshed brand and website experience at www.weil-mclain.com/only-wm

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About Weil-McLain

Weil-McLain^® is a leading North American brand of hydronic comfort heating systems for residential, commercial, and institutional buildings since 1881. Known for innovation and reliability, Weil-McLain is committed to delivering high-efficiency heating solutions that prioritize comfort, energy savings, and sustainability. Weil-McLain continues to serve as a trusted partner by providing Solutions that Matter for the diverse needs of contractors, engineers, architects, homeowners, and facility managers, where products are trusted in homes, offices, schools, restaurants, hotels, and more throughout North America.

WM Technologies, LLC, assembles, sells, and distributes Weil-McLain boilers from Eden, North Carolina, and manufacturers cast iron products in Michigan City, Indiana, with approximately 600 employees across manufacturing facilities, sales locations, and administrative offices in Burr Ridge, Illinois. Backed by the global strength of SPX Technologies Inc, WM Technologies, LLC is dedicated to driving industry innovation and advancing climate-conscious heating solutions. For more information, visit www.weil-mclain.com.

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