• Patented Million Air™ Stainless Steel dual-diameter tubular heat exchanger with lifetime furnace replacement limited warranty
• Two-stage gas valve with revolutionary new TwinComfort™ control technology that allows installer to turn on two-stage operation with the flip of a dipswitch
• SureStart™ Silicon Nitride igniter with patented adaptive learning routine for maximum igniter life
• Energy-saving, quiet four-speed direct-drive circulator blower motor
• Integrated electronic furnace control board with self-diagnostics, low-voltage terminal block, and separate terminals for electronic air cleaner and 24-volt humidifiers
• Control board stores the last five diagnostic codes in memory; simple push-button activation outputs the fault history to a flashing red LED
• Low constant fan mode allows the homeowner to activate the lowest available heating speed to quietly and efficiently circulate air throughout the home during the off cycle
• Self-adjusting feature automatically adjusts furnace to high or low stage based on outside temperature without the need for an outdoor temperature sensor
• Dual-certified for sealed combustion direct vent (2-pipe) or non-direct vent (1-pipe) applications
• Easy-to-install top venting standard; alternate flue/vent located on the right
• Quiet, single-speed induced-draft blower
• All models comply with stringent California NOx emissions standards  

Cabinet Features

• Fully-insulated, heavy-gauge steel cabinet with durable baked-enamel finish
• Designed for multi-position installation: upflow, horizontal left or right
• Airtight solid bottom for side-return applications and easy-cut tabs for effortless removal in bottom air-inlet applications
• Convenient left or right connection for gas and electric service
• Coil and furnace fit flush for most installations