Advanced Thermal Hydronics

ATH’s KN-Series Condensing Cast Iron Boilers are the industry’s only high-efficiency cast iron boilers, backed by a best-in-class 25-year heat exchanger warranty. These boilers combine advanced condensing gas-fired technology with the proven strength and heat retention of cast iron construction. Made in Boyertown, Pennsylvania, every KN-Series unit is cast, machined, wired, and assembled in-house, reflecting ATH’s decades of manufacturing expertise. With models ranging from 200,000 to 4,000,000 BTU/h, KN-Series boilers deliver unmatched American innovation, durability, and performance.

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