98% AFUE All Models, All PositionsFeatures: All Positions 98% AFUE All Other Models, All Positions Modulating Heating Operation (40% - 100% Capacity) Observer Communicating Control System Xtra SEER Variable SpeedECM Blower Motor Supports Singleand Two-Stage Cooling Units Dehumidification Feature In Cooling California Nox Approved Certified 2% or Less Leakage Of Nominal Air Conditioning CFM Delivered When Pressurized to 1-Inch Water Column with All Present Air Inlets, Air Outlets, and Condensate Drain Port(s) Sealed Tougher: Flame Roll-Out Sensors Standard Adjustable Heating Blower Off Delay Factory Set Blower On Delay RPJ Primary Heat Exchanger Stainless Steel Secondary Heat Exchanger High Temperature Limit Control Prevents Overheating Direct Ignition with Silicon Nitride Ignitor Quieter: Operates At Quieter, Lower Heating Rates Variable Speed Induced Draft Combustion Blower Variable Speed ECM Blower Motor Insulated Steel Cabinet Easier To Install and Service: Direct Vent (2-Pipe) or Ventilated Combustion Air 24 Vac Humidifier Terminal Electronic Air Cleaner Terminal 35' (889mm) High, For Ease Of Installation and Room For Service Innovative Knobs For Easy Door Removal and Secure Attachment Factory Shipped For Natural Gas, with Propane Gas Conversion Kits Available Four Position - Upflow/Downflow/Horizontal (Left/Right) Installation At Least Twelve Different Venting Configurations Through The Casing Flue Pipe For Counterflow or Horizontal Applications with Accessory Kit (Order Separately) Concentric Vent Available Simple Troubleshooting Of Gas Valve Self-Configuring and Communicating Control Slide Out Heat Exchanger Assembly and Blower Assembly Warranty * 10 Year No Hassle Replacement Limited Warranty Lifetime Heat Exchanger Limited Warranty with Timely Registration 5 Year Parts Limited Warranty * For Owner-Occupied Residential Applications Only. See Warranty Certificate For Complete Details and Restrictions, Including Warranty Coverage For Other Applications.