- Heavy duty stainless steel tubular heat exchanger - Stainless steel secondary heat exchanger - ComfortNet Communications System compatible - Two stage gas valve provides quiet, economical heating - Durable Silicon Nitride igniter - Quiet two-speed induced draft blower - Uses ComfortNet communicating,two-stage or single-stage thermostats - Self-diagnostic control board with constant memory fault code history output to a dual 7 segment display - Color-coded low voltage terminals with provisions for electronic air cleaner and humidifier - Efficient and quiet variable-speed airflow system gently ramps up or down according to heating or cooling demand - Multiple continuous fan speed options offer quiet air circulation - Cabinet air leakage (QLeak) = <2% - Auto-Comfort and enhanced dehumidification modes available