All KN-Series boilers are available with ourNEW Virtuoso₂
high turndown system. Working off the legendary Tru-Flow air/fuel coupling system; the engineers at ATH have developed an air shutter driven system expanding the KN's turndown ratio to 10:1. The uniquely designed air shutter system is positioned between the venturi and the blower inlet. The air shutter opens and closes electronically depending on the firing rate. The air shutter and blower design protect against intake and flue pressure fluctuations by maintaining blower RPM; providing complete combustion stability across the firing rate without sacrificing performance and reliability at any turndown ratio.