Hydrotherm announced the introduction of their new size offerings to their successful line of KN-Series of condensing cast-iron boilers. The KN-16 and KN-26 are being added to provide a full complement of size offerings across all BTU ranges. Originally introduced in 2002, the KN-Series was the first and is still the only true condensing cast-iron boiler on the market today. Today, it is the flagship boiler of the Hydrotherm franchise.