From inside (document excerpt):
Heat Exchanger Cell Replacement Kit Cancels: 40394DP111-A IIK 394G-55-1 12-98 Installation Instructions Part No. 79988 NOTE: Read the entire instruction manual before starting the installation. This symbol indicates a change since the last issue. NOTE: INTRODUCTION This instruction covers the installation of the heat exchanger cell kit Part No. 79988 in models 394GAD, 394GAZ, 394JAZ, 396GAD, 396GAZ, 396JAZ, 58DP, 58DR, 58DRC, 58GP, 58GS, and 58GSC Gas Furnaces.
A releasing agent (PAM cooking spray or equivalent, must not contain corn or canola oil, aromatic or halogenated hydrocarbons or inadequate seal may occur.) and RTV sealant (G.E. 162 or Dow-Corning 738) are needed before starting installation. DO NOT substitute any other type of RTV sealant. SAFETY CONSIDERATIONS Installing and servicing heating equipment can be hazardous due to gas and electrical components. Only trained personnel should install or service heating equipment. Untrained personnel can perform basic maintenance functions such as cleaning coils, or cleaning and replacing filters. All other operations should be performed by trained service personnel. When working on heating equipment, observe precautions in the literature, on tags, and on labels attached to the unit. Recognize safety information. This is the safety-alert symbol. When you see this symbol on the furnace and in instructions or manuals, be alert to the potential for personal injury. Understand the signal words DANGER, WARNING, and CAUTION. These words are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies a hazard which could result in personal injury or death. CAUTION is used to identify unsafe practices which would result in minor personal injury or product and property damage. NOTE is used to highlight suggestions which will result in enhanced installation, reliability, or operation. Follow all safety codes. Wear safety glasses and work gloves. Have a fire extinguisher available. DESCRIPTION AND USAGE The heat exchanger cell replacement kit can be utilized to restore units having heat exchanger cells that require repair. The cell kit is designed for use in gas furnaces as well as packaged units using the cell design shown in Fig. 1. This heat exchanger cell replacement kit contains the following items: Cell assembly Gasket (burner opening) (vent opening) Screw Installation Instructions 8 1 A98640 Fig. 1–Replacement Cell INSTALLATION IN UPFLOW AND DOWNFLOW FURNACES Step 1–Remove Controls and Burners 1. Turn off gas and electrical supplies to furnace. 2. Remove furnace control and blower access doors. 3. Disconnect gas supply pipe. 4. Disconnect pilot gas supply and thermocouple (when used) from gas valve. 5. Disconnect and mark electrical leads at gas valve. 6. Remove secondary-air shield. 7. Remove main burners. 8. Remove gas valve and manifold assembly. 9. Disconnect leads from main limit switch. Step 2–Remove Casing Parts and Vent Pipe 1. Disconnect and support vent pipe. (Remove vent pipe extension from downflow furnaces.) 1. Remove top filler plate (upflow only). 1. Remove drafthood assembly. 1. Remove sweep sheet. Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations. Book 1 4 PC 101 Catalog No. 535-718 Printed in U.S.A. Form 58DP-1SI Pg 1 12-98 Replaces: 40394DP111-A Tab 6a 8a VENT OPENING 1 2 FLUE BAFFLE BURNER OPENING 3 4 Fig. 2 Step 3–Remove Heat Exchanger Assembly y y y 3 1/2 VENT GASKET 90° VESTIBULE GASKET 3 1/2 A98642 A98641 Fig. 3 Step 5–Reinstall Heat Exchanger Assembly NOTE: Check insulation around top, bottom, and sides of the inner front panel.