Energy Star certification is an important distinction for HVAC manufacturers’ products to achieve. The designation recognizes highly efficient performance, and 2017’s list of the most efficient boilers delivers a bevy of products from a wide range of manufacturers.

Let’s examine one boiler from several of the companies represented on this year’s Most Efficient list.



Buderus SSB Stainless Steel Boiler

The Buderus SSB Series consists of a total of eight models in four separate cabinet sizes with inputs ranging from 85-1,024 MBtuh. These units are applicable for use in small studio units up to commercial buildings.

“The Bosch SSB condensing boiler is designed to work quietly and efficiently with an AFUE of 96 percent,” said Justin Stephens, product manager at Bosch Thermotechnology Corp. “Contractors can count on easy installation due to top connections, a user-friendly interface, and expert support. Thanks to a 10-year full heat exchanger warranty and a five-year warranty for parts and labor, they can also rely on hassle-free maintenance.”

Buderus SSB boilers feature a 5:1 turndown ratio; an onboard control that includes a combination of weather compensation, mod-bus, and BACnet connectivity; a two-wire cascades link; plus terminal wiring; and an optional 0- to 10-vdc interface module. They also feature a factory-installed low-water-cutoff (LWCO) and safety temperature high limiter with a manual reset to speed installation. CSD-1-compliant low- and high-gas pressure switches are factory installed in the larger units (512-1,024 MBtuh).



Mascot FT Series

The Mascot FT by Laars is a condensing combi boiler and water heater featuring 95 percent AFUE. The system contains a robust fire tube heat exchanger and is fully modulating to save fuel.

The natural gas or LP-fired unit is offered in many sizes and configurations, including 120-, 140-, and 199-MBtuh combi boilers and water heaters, or as 80-, 100-, 120-, 140-, and 199-MBtuh heating-only boilers. Combi models include an integrated, mini-indirect tank resulting in superior domestic hot water performance by minimizing temperature fluctuations and providing endless hot water quickly.

The integrated mini-indirect tank is always kept charged with hot water. When domestic hot water begins to be used, the boiler fires and immediately begins to produce more hot water.

The Mascot FT can be ordered as a floor-standing or wall-hung unit. It includes an easy-to-use advanced control system, a conformal encapsulated control board protected from moisture, a gas leak detection system that will shut down the boiler if gas leak is detected for added safety, an outdoor reset, a domestic hot water priority, a primeless condensate trap, zero clearance installation, and venting up to 100 feet.

An isolated compressor compartment reduces noise, and a state-of-the-art compressor combines reliability and efficiency with quiet operation. The fan guard design yields quiet and efficient operation, and a composite base pan distributes and dampens sound.

“One thing that sets the Mascot FT apart is its fire tube heat exchanger design,” said Chuck O’Donnell, director of marketing, LAARS Heating Systems Co. “It uses both stainless steel on the water side and aluminum on the fire side, which helps transfer heat 10 times faster than just stainless steel alone, greatly improving the overall efficiency of the product. Something else that sets it apart is [that] the circuit board is conformal coated, which basically means it’s coated in a protective plastic layer so that if there are any leaks, or if someone is installing it and gets some water on it, the board is protected from moisture. It also features a gas leak detector, so if there is ever a gas leak, it will detect that and then shut the boiler down and display a code. That’s another safety feature that goes above and beyond.”



GWM Series

The GWM-IE boiler features an efficiency of up to 95 percent AFUE with fuel flexibility that utilizes either natural or LP gas as a heat source.

This boiler also features Electronic Ignition Control, which burns fuel only when necessary and reduces energy costs; a stainless steel, finned-tube heat exchanger; a stainless steel mesh burner that provides greater resistance to corrosion and oxidation than aluminized steel burners; a factory-installed low water cut off (LWCO) switch that exceeds industry requirements to ensure safer operation; a chlorinated polyvinyl chloride (CPVC) flue condensate collector that offers greater protection against corrosion and leaking; sealed combustion that reduces noise for quiet comfort in any living space; and a wall-hung design.

“The Lennox GWM-IE boiler is a feature-rich gas boiler for homeowners who value comfort and appreciate a high level of efficiency,” said Jill Murphy, senior product marketing manager, heating, Lennox. “For the Lennox dealer, this boiler provides a very low installation cost. The GWM-IE boiler offers an energy efficiency [AFUE] of up to 95 percent, modulating capability with a 5:1 turn down ratio, sealed combustion, and a built-in primary/secondary piping. The boiler features all this and a 10-year parts warranty, which gives homeowners added peace of mind.”



KNIGHT Fire Tube Boiler

The KNIGHT Fire Tube Boiler in a wall-mount configuration features 95 percent AFUE efficiency, is enabled for CON-X-US remote connectivity, and allows for a more flexible installation with top and bottom water connections.

“Multiple water connection options reduce installation cost, complexity, and the amount of piping needed for a job — that’s an extremely appealing feature of the new wall-mount KNIGHT Fire Tube Boiler,” said Dan Rettig, residential boiler product manager, Lochinvar LLC.

The boiler also operates with low pressure drop. The design incorporates a small volume of water in the heat exchanger, which allows the boiler to be installed in a primary/secondary or a full-flow piped system. There is no need to change the piping to accommodate the boiler as the boiler adapts to the system. This flexibility allows for a faster, more cost-effective boiler upgrade.

Additionally, the newest version of the Smart System allows for easier setup and navigation of parameters. New features include domestic hot water recirculation pump control, LOCK-N-LINK USB programming, larger user interface, cascade leader redundancy, and modulation factor for fine tuning aggressiveness.



Peerless® PureFire® Series

Peerless Purefire High-efficiency Condensing Gas Boilers feature nine available sizes for residential and commercial applications; direct vent and sealed combustion; a fully modulating burner for maximum efficiency; factory-tested, pre-mixed gas burner technology; and a sleek, modern design with easy access to controls.

“From a cottage to convention hall, PB Heat has a Peerless brand product, including the high-efficiency Peerless PureFire to meet your needs,” said Mike McDonnell, vice president of marketing, PB Heat LLC.

The PureFire is environmentally friendly, features LoNOx operation, and is ETL-certified for both the U.S. and Canada. The PureFire is also cascade capable for up to 16 boilers.



Evergreen™ Series

The 95 percent AFUE Evergreen boiler features cutting-edge technology with simple controls; flexible functionality for multiple applications; a durable design; and is easy to install, use, and maintain.

The unit is adaptable for most heating needs, including light commercial or large residential applications and for single- or multi-boiler installations. Evergreen offers quiet operation, an aesthetically pleasing design, floor-standing or wall-mount options, and environmental sustainability.

“Our new Evergreen boiler was built with contractors in mind,” said Mike Boyd product manager with Weil-McLain. “It was developed after detailed analysis and testing by Weil-McLain engineers plus extensive feedback from customers. The durable unit is adaptable for most heating demands to effortlessly extend comfort levels to every area of a property from multiple in-home zones to pools for years to come.”

The boiler’s straightforward and user-friendly design makes installation easy for contractors, installers, or service providers. The unit features a guided setup wizard, an easy-to-understand graphical user interface, simple controls, and 10 heating system presets for quick setup.

For the residential and light commercial customer who requires a multiple boiler setup, the Evergreen offers the ability to cascade eight boilers together and ZoneStacking™ for up to 24 programmable zones with no external panel required.

“The Evergreen derives its name from its sustainable design and represents the leading edge in energy-efficient boilers,” said Boyd. “Installation of the unit could allow homeowners to qualify for local utility rebates, if available.


For a complete list of Energy Star’s Most Efficient 2017 boilers, visit

Publication date: 9/25/2017

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