From inside (document excerpt):
58CTA/58CTX 2 Stage Deluxe Induced-Combustion 4-Way Multipoise Furnace Installation, Start-up, Operating, and Service and Maintenance Instructions -Series 100 THE WEATHERMAKER® 8000TS GAS FURNACE The 58CTA/CTX Two-Stage, 4-way Multipoise Gas Furnaces offer unmatched comfort in their class with ComfortHeat Technology in an 80% AFUE gas furnace. You get the benefits of a ComfortHeat Technology furnace: reduced drafts, reduced sound levels, longer cycles, less temperature swings between cycles, and less temperature differences between rooms.
Its exclusive, intelligent microprocessor control adapts to the heating needs of the home by automatically adjusting high and low heat times to maximize comfort. The 58CTA/CTX furnaces are approved for use with natural or propane gas, and the 58CTX is also approved for use in Low NOx Air Quality Management Districts. STANDARD FEATURES – ComfortHeat Technology Two-stage heating with single-stage thermostat Very low operating sound through low-stage operation and QuieTech system – Media Filter Cabinet Available – Microprocessor based “smart ” control center Adapts heating stages to meet demand Dehumidification selection for summer-time cooling Adjustable heating air temperature rise Adjustable cooling airflow ComfortFan–Constant fan speed selectable from thermostat LED diagnostics and self test feature Stores fault codes during power outages – 4-way Multipoise furnace, 13 vent applications – Hot surface ignition (HSI) – Draft safeguard switch to ensure proper furnace venting – All Models Chimney-Friendly when used with the accessory vent kit. – Insulated blower compartment – Heat pump compatible – Residential installations eligible for consumer financing through the Retail Credit Program – Twinning in Upflow, Downflow and Horizontal LIMITED WARRANTY – 20-year warranty on “Super STM ” heat exchanger – 5-year parts warranty on all other components Catalog No: 535-80102 Form No. 58CT-4SI 12-02 2-Stage Deluxe Induced-Combustion 4-Way Multipoise Furnace Cancels: II 312A-45-2 II 312A-45-3 12-02 Installation, Start-up, Operating, and Service and Maintenance Instructions Series 100/A NOTE: Read the entire instruction manual before starting the installation. This symbol indicates a change since the last issue. TABLE OF CONTENTS Ca EFFICIENCY RATING CERTIFIED SAFETY CONSIDERATIONS .2 INTRODUCTION 3 CODES AND STANDARDS 3 Safety .3 General Installation .