Classic 18" width dimension for tight replacement jobs;Beckett gas burners are standard;100% fired and tested: All units and each component are tested on the manufacturing line;30 second blower delay at start-up assures a warm duct temperature at furnace start-up. Adjustable blower off settings (60, 90, 120 and 180 seconds);30 second post purge increases life of heat exchanger;Hot surface igniter - Innovative application of a silicon nitride type igniter. Utilizes proven Smartlite technology;Color coded wire harness - Designed to fit the components, all with quick-connect fittings for ease of service and replacement;Flexible category IV venting system - May be vertically or horizontally vented using either a onepipe or two-pipe system for maximum flexibility in installation;High Static Blowers- All models equipped with high static blowers;Tubular primary heat exchanger- Heavy gauge aluminized steel heat exchanger and stainless steel secondary heat exchanger assures a long life;Multi-speed direct drive blower- Energy-efficient, brushless DC (ECM). Designed to provide a wide range of blower capapcities. Switches on PCB to provide ultra easy motor selection;LP convertible: Simple burner orifice and regulator spring change for ease of convertibility;Diagnostic lights for easy troubleshooting without counting flashes- Dedicated light for flame signal strength and 2 lights in combination to indicate all other fault codes with easy to recognize states without counting flashes