Product Features: Energy-efficient multi-speed ECM blower motor, heavy-duty stainless-steel, tubular heat exchanger, stainless-steel secondary heat exchanger, two-stage gas valve provides quiet, economical heating, durable Silicon Nitride Igniter, quiet two-speed induced draft inducer, self-diagnostic control board with constant memory fault code, Color-coded low-voltage terminals with provisions for electronic air cleaner and humidifier, low continuous fan speed options offer quiet air circulation, all models comply with California 40 ng/J Low NOx emissions standards, multi-position installation: upflow, horizontal left or right, cabinet air leakage (QLeak) = 2%, heavy-gauge steel cabinet with durable baked-enamel finish.