LENNOX Furnace/Heater, Gas Manual L0806909

User Manual: LENNOX LENNOX Furnace/Heater, Gas Manual LENNOX Furnace/Heater, Gas Owner's Manual, LENNOX Furnace/Heater, Gas installation guides

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®GAS UNITSKITS AND ACCESSORIESTechnica_:blicationsLitho U.S.A.©2000 Lennox Industries Inc.Dallas, Texas, USA 504,122M 90UGF/G26/G32 REPLACEMENT1/2000Supersedes 503,908M HEAT EXCHANGERINSTALLATION INSTRUCTIONS FOR REPLACEMENT HEAT EXCHANGER(LB-91398A,B,C,D & E) FOR USE WITH 90UGF/G26/G32 SERIES UNITSPackage 1 of 1 contains the following:1 - Heat exchanger assembly1 - Burner box gasket1 - Burner box1 - Burner cluster1 - Rollout switch assembly4 - Combustion air blower screws1 - Wiring diagram sticker1 - Rollout switch wire (blue)1 - Blower control wire (orange)1 - Wire nutNote -Early model G26 units were manufactured with ahard plastic flue "Y" between the combustion air blower andthe top of the unit. Later models were built using a softrubber flue transition between the combustion air blowerand the flue collar.G26 and 90UGF units have also been manufactured usingtwo types of ignition/blower control systems, Early modelswere equipped with an intermittent pilot ignition that had aseparate ignition and blower control. The later modelshave hot surface ignition and an integrated ignition andblower control.Check equipment for shipping damage. If you find anydamage, immediately contact the last carrier.These instructions are intended as a general guide and donot supersede local codes in any way. Figure 8 illustrates thegeneral part placement of the 90UGF/G26/G32 series furnace.See table 1 for unit model numbers and correspondingreplacement kits,TABLE 1REPLACEMENT REPLACEMENTUNIT MODEL #KIT # KIT CATALOG #90UGFA2-50G26Q2-50 LB_91398A 84K4590UGFA3-50G26Q3*5090UGFA3-75G26Q3W5 LB*91398B 84K46G32W5G26Q4/5-75 LB*91398E 64L0790UGFA3/4-100G26Q3/4-100 LB-91398C 84K47G26Q4/5-100G32_10090UGFA4/5-125G26Q3/4-125 LB*91398D 84K48G26Q4/5-125G32-125ELECTROSTATIC DISCHARGE (ESD)Precautions and ProceduresCAUTIONRefer to figure 8 when disassembling unit.NOTE- Figure 8 illustrates units built with the SureLight hotsurface ignition and a soft rubber flue transition.Use papers or protective covering in front of furnace whileremoving heat exchanger assembly,1 - Turn off electrical and gas power supplies to furnace.2 - Remove upper and lower furnace access panels.3 - Remove four screws around air intake fitting and liftintake pipe up and away.4 - Units with soft rubber flue transition - Loosen theclamp between the flue transition and flue collar,Remove the flue collar mounting screw from the topcap and pull the flue collar / exhaust pipe up and awayfrom the cabinet. Detach and remove the top cap fromcabinet and supply air plenum.Page 1
Units with hard plastic flue Y - Loosen the lowerclamp of no-hub connector at exhaust line and lift pipeup and away. Detach unit top cap from cabinet andsupply air plenum and remove the top cap.5 - If the electrical field make-up box is located inside theunit, you must remove it.6 - Mark all gas valve wires and disconnect them from thevalve.7 - Disconnect gas supply from the gas valve.8 - Disconnect and remove the condensate line from thecondensate trap (which is on the bottom of thecollector box), Turn the adapter fittingcounterclockwise to remove it from the condensatetrap. The fitting has standard right-hand threads,9 - Carefully remove the spring clip and boot from thecondensate trap. Drain the condensate trap, andcatch the condensate into a shallow pan. Do not spillwater in the control box.10 - Remove the drain tube from the cold end collector boxelbow.11 - Units with hard plastic flue Y- Remove two screwsfrom the flue Y trap at the cabinet door flange.12 - Disconnect the 2-pin plug (3-pin plug on G32)from thecombustion air blower. Remove the four screws fromthe combustion air blower, then remove the flue Y orthe flue transition and the blower assembly from theunit. Do not misplace the combustion air blowerorifice.13 - Units with hard plastic flue Y- Invert the combustionair blower/flue assembly, and drain the flue Y into thefloor drain.14-Units with SureLight hot surface ignition -Disconnect ignitor lead 2-pin plug located just outsideof burner box. Mark and disconnect sensor wire fromignition control.Units with intermittent pilot ignition - Mark anddisconnect ignitor lead and sensor wire from ignitioncontrol.15 - Mark and disconnect pressure switch tubing from bothsides of the pressure switch.16 - Units with SureLight hot surface ignition - Removethe limit switch, pressure switch, and the attachedwiring harness from the vestibule panel.Units with intermittent pilot ignition - Remove thelimit switch, pressure switch, ignition control with itsbracket and the attached wiring harness from thevestibule panel.17 - Loosen the two screws that hold the gas manifoldsupport at the vestibule panel.18 - Remove the four burner box screws at the vestibulepanel and remove burner box and gas valve/manifoldassembly with bracket.19- Disconnect the 9-pin plug from the blowercompartment at the blower deck.20 - Remove the 9-pin plug above the blower deck.21 - Remove the two screws from the front cabinet flangeat the blower deck, Remove the front screws from thecabinet at the blower deck on left and right sides.Cabinet sides must be slightly spread to clear heatexchanger passage.22- Remove screws along vestibule sides and bottomwhich secure vestibule panel and heat exchangerassembly to cabinet. Remove heat exchanger.23 - Remove existing insulation from the mounting angleslocated on the cabinet sides.24-Install the replacement heat exchanger into thecabinet, and make sure that the clamshells of the heatexchanger assembly are resting in the notches of thesupport which is located at the rear of the cabinet. Toview the clamshell, remove the indoor blower andexamine it through the blower opening.25-Resecure the heat exchanger supporting screwsalong the vestibule sides and bottom.26 - Resecure cabinet screws on sides and front flange atblower deck,27 - Units with SureLight hot surface ignition - Reinstalllimit switch and pressure switch, with attached wiringharness, on the vestibule panel.Units with intermittent pilot ignition - Reinstall thelimit switch, pressure switch and ignition control withits bracket and the attached wiring harness on thevestibule panel.28 - Reinstall the 9-pin plug to blower deck and reconnect itto the the 9-pin plug from below the blower deck.29 - From the original burner box, unscrew and remove theburner box cover, and the gas manifold.30 - Unscrew and remove the fresh air intake fitting from topof old burner box. Unscrew patch plates from left andright sides of burner box.31 - Unscrew and remove the gas manifold and old burnercluster from the old burner box. On intermittent pilotG26 units, handle the gas valve and burner clustertogether; this will prevent the pilot tube from beingdamaged.32 - Furnaces with intermittent pilot ignition - Unscrewand remove original pilot assembly from the old burnercluster along with "D" wire grommet. Reattach the pilotassembly to new cluster in the same location. Whenyou install the burner cluster, the raisedtoggle locksmust be pointing up. Install the pilot assembly on theunderside of the burner cluster, between the tworightmost burners. See figure 1.All other units - Remove SureLight ignitor bracket andsensor bracket from the old burner cluster along with"D" wire grommet. Reattach ignitor and sensor to thenew burner cluster. The raised toggle locks in theburner cluster should be pointing up when installed inthe unit. Install the SureLight ignitor on the bottom of theburner cluster, and install the sensor to the topside ofthe bumer cluster. See Figure 2.Page 2

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