Sterling unveils Xcelon, ultra high efficiency make-up air rooftop system

Xcelon combines the latest in hydronics, efficiency, and air handling for large rooftop systems

WESTFIELD, Mass. – Surpassing the performance and efficiency of all other rooftop systems, Sterling HVAC announced today the commercialization of the Xcelon system, the first rooftop make-up air unit that combines innovative hydronic condensing boiler technology with advanced air distribution and heat recovery methods, for unparalleled levels of efficiency up to 98%.

Conceptualized and developed by Sterling, well-regarded throughout the industry as a leader in HVAC innovation, Xcelon’s unique engineering integrates hydronic technology, a new air distribution system, and an integrated control platform to produce ultra-high efficiencies, making it a truly revolutionary step in make-up air rooftop systems.

Chuck Perry, Director of Sales & Marketing, added that key benefits of the new system are its environmental and energy-efficient strengths.

“Xcelon is a combination of all the best thinking we have at our disposal, both from a design and engineering perspective,” said Perry. “With efficiencies often approaching 98%, an innovative self-contained hydronic boiler design and unique heat recovery system, it’s the greenest roof top system ever developed.”

Available with a 800 – 1,200 MBH heating capacity, Xcelon utilizes an innovative factory charged, closed loop 35% glycol mix for freeze protection with no separate water supply required. It can offer airflow of 4,501 – 10,000 CFM.

Xcelon systems have been in testing in some of the coldest environments in the U.S. and Canada for more than two years, but have not been released until today to ensure the technology was performing as designed. With its unique air handler, heat exchanger and heat recovery system, Xcelon has surpassed expectations and is now ready for commercialization.

Key features include:

·      Up to 98 % Efficient by Utilizing a High Efficiency Hydronic Condensing Boiler

·      800 – 1,200 MBH Heating Capacity

·      4,501 – 10,000 CFM Airflow

·      Closed 35% Glycol Mix Loop – No separate water supply required

·      +/-1 Temperature Accuracy

·      BMS Communication – Modbus Standard LonWorks & BACnet Optional

·      Integral Spring Isolators for Vibration Control and Quiet Operation

·      Designed for 100% Outside Air, Optional Return Air and a Variety of Economizer Controls

·      Exclusive Heat Loss Recovery System

·      Fully Modulating Gas Valve and VFD

·      Service and Installation Friendly Design


The Xcelon is currently available in a heating-only configuration with Phase 2, an integral packaged cooling system including condensing coils, compressors and factory-piped and charged refrigerant due out in early 2015. To learn more about Xcelon visit:



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About Xcelon

Xcelon is the result of a long-term research and development collaborative between Sterling HVAC and Mestek, Inc., parent company of Sterling, and an industry leader in hydronic heating & cooling technologies. Mestek, Inc. is a family of manufacturers of HVAC equipment and automated manufacturing machinery with years of experience and a history of innovation.