- Aluminized-steel tubular heat exchanger - Efficient, quiet variable-speed circulator motor - ComfortNet Communications System compatible - Durable 110-volt Silicon Nitride Igniter - Multiple continuous fan speed options offer quiet air circulation - Cabinet air leakage (QLeak) = 2% - Electronic control board with self-diagnostics and provisions for air cleaner and humidifier - Auto-comfort mode for enhanced dehumidification - Quiet two-speed induced draft blower - All models comply with California Low NOx emissions standards