INSTALLATION INSTRUCTIONS Dallas, Texas USA SL297UHNV

Installation - Setting EquipmentWARNINGDo not connect the return air duct to the back of thefurnace. Doing so will adversely affect the operationof the safety control devices, which could result inpersonal injury or death.WARNINGBlower access panel must be securely in place whenblower and burners are operating. Gas fumes, whichcould contain carbon monoxide, can be drawn intoliving space resulting in personal injury or death.Upflow ApplicationsThe SL297UHNV gas furnace can be installed as shippedin the upflow position. Refer to FIGURE 6 for clearances.Select a location that allows for the required clearancesthat are listed on the unit nameplate. Also consider gassupply connections, electrical supply, vent connection,condensate trap and drain connections, and installationand service clearances 24 inches (610 mm) at unit front.The unit must be level from side to side. The unit may bepositioned from level to ½” toward the front. See FIGURE5.Allow for clearances to combustible materials as indicatedon the unit nameplate.SETTING EQUIPMENTUPFLOW APPLICATIONPlace level on blowerdeck screws to checkforward tiltPlace level on the front blowerdeck to check side to sideUNITFRONTAIR FLOW1/2”max.SIDE VIEWHORIZONTAL APPLICATIONUNITFRONTAIR FLOW1/2”max.END VIEWFRONT VIEWUnit must be level side-to-side. Unit may be positioned from level to 1/2” toward the front to aid in draining.FIGURE 5Page 6

WARNINGImproper installation of the furnace can result inpersonal injury or death. Combustion and flueproducts must never be allowed to enter the returnair system or air in the living space. Use sheet metalscrews and joint tape to seal return air system tofurnace. In platform installations with furnacereturn, the furnace should be sealed airtight to thereturn air plenum.A door must never be used as a portion of the returnair duct system. The base must provide a stablesupport and an airtight seal to the furnace. Allowabsolutely no sagging, cracks, gaps, etc.For no reason should return and supply air ductsystems ever be connected to or from other heatingdevices such as a fireplace or stove, etc. Fire,explosion,carbon monoxide poisoning, personalinjuryand/or property damage could result.Return Air GuidelinesReturn air can be brought in through the bottom or eitherside of the furnace installed in an upflow application. If thefurnace is installed on a platform with bottom return, makean airtight seal between the bottom of the furnace and theplatform to ensure that the furnace operates properly andsafely. The furnace is equipped with a removable bottompanel to facilitate installation.Markings are provided on both sides of the furnace cabinet for installations that require side return air. Cut thefurnace cabinet at the maximum dimensions shown onpage 2.Refer to Engineering Handbook for additional information.SL297UHNV applications which include side return airand a condensate trap installed on the same side of thecabinet (trap can be installed remotely within 5 ft.) requireeither a return air base or field-fabricated transition to accommodate an optional IAQ accessory taller than 14.5”.See FIGURE 7.Side Return Air(with transition and filter)Installation ClearancesTopLeft Side20” X 25” X 1”(508mmX635mmX 25mm)Air FilterRight SideBottom (Floor)Top/Plenum1 in. (25 numTransitionFIGURE 7*Front clearance in alcove installation must be 24 in. (610 mm).Maintain a minimum of 24 in. (610 mm) for front service access.†Allow proper clearances to accommodate condensate trap.‡For installations on a combustible floor, do not install the furnacedirectly on carpeting, tile or other combustible materials otherthan wood flooring.FIGURE 6Page 7

Optional Return Air Base(Upflow Applications Only)CONDENSATETRAPFURNACEFRONTINDOOR AIRQUALITYCABINET(PCO, FilterCabinet, etc.)AIR FLOW17 1/2 (446) B Width (50W98)21 (533) C Width (50W99)24 1/2 (622) D Width (51W00)IF BASEIS USEDWITHOUTIAQ CABINET,A SINGLERETURN AIRPLENUMMUSTCOVER BOTHUNIT ANDRETURNAIR BASEOPENINGS1 23(584)Overall(Maximum)3 1/4(83)17 1/4(184)Unit side return airOpening12Minimum11 (279)Maximum14 (356)(570)Overall(Maximum)SIDE RETURNAIR OPENINGS(Either Side)5 5/8(143)23(584)26 7/8(683)OPTIONALRETURNAIR BASE1 22 7/163/4(19)SIDE VIEWFRONT VIEWNOTE- Optional side return air filter kits are not for use with return air base.1 Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in. (584 x 279 mm).The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return airopening. The size of the opening must not extend beyond the markings on the furnace cabinet.2 To minimize pressure drop, the largest opening height possible (up to 14 inches) is preferred.Figure 8Removing the Bottom PanelRemoving the Bottom PanelRemove the two screws that secure the bottom cap to thefurnace. Pivot the bottom cap down to release the bottompanel. Once the bottom panel has been removed, reinstallthe bottom cap. See FIGURE 9.Horizontal ApplicationsWARNINGDo not install the furnace on its front or back. SeeFIGURE 10.See figure 4.ScrewBottom CapBottom PanelFrontFIGURE 9BackFIGURE 10Page 8

The SL297UHNV furnace can be installed in horizontalapplications with either right- or left-hand air discharge.Refer to FIGURE 11 for clearances in horizontal applications.HORIZONTAL SUSPENSION KITInternal Brace(provided with kit)Metal Strap(typical)Horizontal ApplicationInstallation ClearancesBracket(typical)Right-Hand DischargeLeft EndRight EndAirFlowAirFlowAirFlowBottom (Floor)**Left-Hand DischargeTopLeft EndAirFlowRight EndAirFlowBottom (Floor)**Top1Front*1Back1Ends1Vent1Floor1‡*Front clearance in alcove installation must be 24 in. (610 mm).Maintain a minimum of 24 in. (610 mm) for front service access.**An 8” service clearance must be maintained below the unit toprovide for servicing of the condensate trap.‡For installations on a combustible floor, do not install the furnacedirectly on carpeting, tile or other combustible materials otherthan wood flooring.FIGURE 11Suspended Installation of Horizontal UnitThis furnace may be installed in either an attic or a crawlspace. Either suspend the furnace from roof rafters orfloor joists, as shown in FIGURE 12, or install the furnaceon a platform, as shown in FIGURE 13. A horizontal suspension kit (51W10) may be ordered from Lennox or useequivalent.NOTE - Heavy-gauge sheet metal straps may be used tosuspend the unit from roof rafters or ceiling joists. Whenstraps are used to suspend the unit in this way, supportmust be provided for both the ends. The straps must notinterfere with the plenum or exhaust piping installation.Cooling coils and supply and return air plenums mustbe supported separately.FIGURE 12NOTE - When the furnace is installed on a platform or withthe horizontal suspension kit in a crawlspace, it must beelevated enough to avoid water damage, accommodatedrain trap and to allow the evaporator coil to drain.Platform Installation of Horizontal Unit1 - Select location for unit keeping in mind service andother necessary clearances. See FIGURE 11.2 - Construct a raised wooden frame and cover framewith a plywood sheet. If unit is installed abovefinished space, install an an auxiliary drain pan underunit. Set unit in drain pan as shown in FIGURE 13.Leave 8 inches for service clearance below unit forcondensate trap.3- Provide a service platform in front of unit. Wheninstalling the unit in a crawl space, a proper supportplatform may be created using cement blocks.4 - Route auxiliary drain line so that water draining fromthis outlet will be easily noticed by the homeowner.5 - If necessary, run the condensate line into a condensatepump to meet drain line slope requirements. Thepump must be rated for use with condensingfurnaces. Protect the condensate discharge linefrom the pump to the outside to avoid freezing.6 - Continue with exhaust, condensate and intake pipinginstallation according to instructions.INTAKE PIPE*GAS CONNECTIONEXHAUST PIPE*Gas connector may beused for Canadianable by local authorityhaving jurisdiction.SERVICE PLATFORMFIGURE 13Page 9RAISEDPLATFORM

Return Air -- Horizontal ApplicationsReturn air may be brought in only through the end of afurnace installed in the horizontal position. The furnace isequipped with a removable bottom panel to facilitate installation. See FIGURE 9.FiltersThis unit is not equipped with a filter or rack. A field-provided high velocity rated filter is required for the unit tooperate properly. TABLE 1 lists recommended filter sizes.A filter must be in place whenever the unit is operating.IMPORTANTIf a highefficiency filter is being installed as part of thissystem to ensure better indoor air quality, the filter mustbe properly sized. Highefficiency filters have a higherstatic pressure drop than standardefficiency glass/foamfilters. If the pressure drop is too great, system capacityand performance may be reduced. The pressure dropmay also cause the limit to trip more frequently duringthe winter and the indoor coil to freeze in the summer,resulting in an increase in the number of service calls.Before using any filter with this system, check thespecifications provided by the filter manufacturer againstthe data given in the appropriate Lennox ProductSpecifications bulletin. Additional information is providedin Service and Application Note ACC002 (August 2000).TABLE 1Filter SizeFurnaceCabinet WidthSide Return17-1/2”16 X 25 X 1 (1)16 X 25 X 1 (1)21”16 X 25 X 1 (1)20 X 25 X 1 (1)Bottom ReturnDuct SystemUse industry-approved standards to size and install thesupply and return air duct system. FIGURE 14 shows thecorrect supply and return duct installation. Refer to ACCAManual D. This will result in a quiet and low-static systemthat has uniform air distribution.NOTE - This furnace is not certified for operation in heating mode (indoor blower operating at selected heatingspeed) with an external static pressure which exceeds 0.8inches w.c. Operation at these conditions may result inimproper limit operation.Supply Air PlenumIf the furnace is installed without a cooling coil, a removable access panel should be installed in the supply airduct. The access panel should be large enough to permit inspection of the heat exchanger. The furnace accesspanel must always be in place when the furnace is operating and it must not allow leaks. For horizontal units, install self tapping screws in the three evaporator coil screwholes made for horizontal applications to seal the top capto the vestibule panel.Return Air PlenumNOTE - Return air must not be drawn from a roomwhere this furnace, or any other gas-fueled appliance(i.e., water heater), or carbon monoxide-producing device (i.e., wood fireplace) is installed.When return air is drawn from a room, a negative pressureis created in the room. If a gas appliance is operating ina room with negative pressure, the flue products can bepulled back down the vent pipe and into the room. Thisreverse flow of the flue gas may result in incomplete combustion and the formation of carbon monoxide gas. Thisraw gas or toxic fumes might then be distributed throughout the house by the furnace duct system.Return air can be brought in through the bottom or eitherside of the furnace (return air brought into either side offurnace allowed only in upflow applications). If a furnacewith bottom return air is installed on a platform, make anairtight seal between the bottom of the furnace and theplatform to ensure that the unit operates properly andsafely. Use fiberglass sealing strips, caulking, or equivalent sealing method between the plenum and the furnacecabinet to ensure a tight seal. If a filter is installed, size thereturn air duct to fit the filter frame.SUPPLYAIRInstall self tapping screwsto seal any potential airleaksSUPPLYAIRUPFLOW UNITHORIZONTAL UNITFIGURE 14Page 10

Pipe & Fittings SpecificationsAll pipe, fittings, primer and solvent cement must conformwith American National Standard Institute and the American Society for Testing and Materials (ANSI/ASTM) standards. The solvent shall be free flowing and contain nolumps, undissolved particles or any foreign matter that adversely affects the joint strength or chemical resistance ofthe cement. The cement shall show no gelation, stratification, or separation that cannot be removed by stirring. Refer to TABLE 2 for approved piping and fitting materials.SL297UHNV exhaust and intake connections aremade of PVC. Use PVC primer and solvent cementwhen using PVC vent pipe. When using ABS ventpipe, use transitional solvent cement to makeconnections to the PVC fittings in the unit.PIPING AND FITTINGS SPECIFICATIONSSchedule 40 PVC (Cellular Core Pipe)D1785F891Schedule 40 PVC (Fittings)D2466Schedule 40 CPVC (Pipe)F441Schedule 40 CPVC (Fittings)F438SDR-21 PVC or SDR-26 PVC (Pipe)D2241SDR-21 CPVC or SDR-26 CPVC (Pipe)F442Schedule 40 ABS Cellular Core DWV (Pipe)F628Schedule 40 ABS (Pipe)D1527Schedule 40 ABS (Fittings)D2468ABS-DWV (Drain Waste & Vent) (Pipe &Fittings)D2661PVC-DWV (Drain Waste & Vent) Pipe &Fittings)D2665PRIMER & SOLVENT CEMENTASTMSPECIFICATIONPVC & CPVC PrimerF656PVC Solvent CementD2564CPVC Solvent CementABS Solvent CementPVC/CPVC/ABS All Purpose Cement ForFittings & Pipe of the same materialF493D2235D2564, D2235, F493ABS to PVC or CPVC Transition SolventCementPVC & ABS & NORYL Transition SolventCement WELD-ON 4052CANADA PIPE & FITTING & SOLVENTCEMENTSolvent cements for plastic pipe are flammableliquids and should be kept away from all sources ofignition. Do not use excessive amounts of solventcement when making joints. Good ventilationshould be maintained to reduce fire hazard and tominimize breathing of solvent vapors. Avoid contactof cement with skin and eyes.IMPORTANTTABLE 2Schedule 40 PVC (Pipe)CAUTIOND3188Use PVC primer and solvent cement or ABS solvent cement meeting ASTM specifications, refer to TABLE 2.As an alternate, use all purpose cement, to bond ABS,PVC, or CPVC pipe when using fittings and pipe made ofthe same materials. Use transition solvent cement whenbonding ABS to either PVC or CPVC.Low temperature solvent cement is recommended duringcooler weather. Metal or plastic strapping may be used forvent pipe hangers. Uniformly apply a liberal coat of PVCprimer for PVC or use a clean dry cloth for ABS to cleaninside socket surface of fitting and male end of pipe todepth of fitting socket.Canadian Applications Only - Pipe, fittings, primer andsolvent cement used to vent (exhaust) this appliance mustbe certified to ULC S636 and supplied by a single manufacturer as part of an approved vent (exhaust) system. Inaddition, the first three feet of vent pipe from the furnaceflue collar must be accessible for inspection.NOTE - The intake coupling on the furnace is ABS material. Use transitional solvent to make connections toPVC pipe.NOTE - Vent pipe must be installed with flue couplingSee FIGURE 17.MARKINGPVC & CPVC Pipe and FittingsPVC & CPVC Solvent CementABS to PVC or CPVC Transition CementPOLYPROPYLENE VENTING SYSTEMULCS636PolyPro by DuraventInnoFlue by CentrothermPage 11

TABLE 3OUTDOOR TERMINATION USAGE*STANDARDInput Size040060080Vent PipeDia. in.CONCENTRICWall KitFlush MountKit2 inch3 inch51W11 (US)51W12(CA)22G44 (US)430G28 (CA)44J40 (US)481J20 (CA)FieldFabricated1-1.2 inch2 inch3 inch71M80 (US)444W92(CA)69M29 (US)444W92(CA)60L46 ES5YESYESYES33YESYES5YESYESYESNOTE - Standard Terminations do not include any vent pipe or elbows external to the structure. Any vent pipe or elbows external to the structure must be included in totalvent length calculations. See vent length tables.* Kits must be properly installed according to kit instructions.1 Requires field-provided outdoor 1-1/2” exhaust accelerator.2 Concentric kits 71M80 and 44W92 include 1-1/2” outdoor accelerator, when uses with 040 and 060 input models.3 Flush mount kits 51W11 and 51W12 includes 1-1/2 in. outdoor exhaust accelerator, required when used with 040, 060 and 080 input models.4 Termination kits 30G28, 44W92, 4493 and 81J20 are certified to ULC S636 for use in Canada only.5 See TABLE 8 for vent accelerator requirements.Joint Cementing ProcedureAll cementing of joints should be done according to thespecifications outlined in ASTM D 2855.DANGERDANGER OF EXPLOSION!Fumes from PVC glue may ignite during systemcheck. Allow fumes to dissipate for at least 5 minutesbefore placing unit into operation.1 - Measure and cut vent pipe to desired length.2 - Debur and chamfer end of pipe, removing any ridgesor rough edges. If end is not chamfered, edge of pipemay remove cement from fitting socket and result ina leaking joint.NOTE - Check the inside of vent pipe thoroughly forany obstruction that may alter furnace operation.3 - Clean and dry surfaces to be joined.4 - Test fit joint and mark depth of fitting on outside ofpipe.5 - Uniformly apply a liberal coat of PVC primer for PVCor use a clean dry cloth for ABS to clean inside socketsurface of fitting and male end of pipe to depth offitting socket.Page 12NOTE - Time is critical at this stage. Do not allowprimer to dry before applying cement.6 - Promptly apply solvent cement to end of pipe andinside socket surface of fitting. Cement should beapplied lightly but uniformly to inside of socket. Takecare to keep excess cement out of socket. Applysecond coat to end of pipe.7- Immediately after applying last coat of cement topipe, and while both inside socket surface and endof pipe are wet with cement, forcefully insert end ofpipe into socket until it bottoms out. Turn

A communicating thermostat must be used in communicating applications. In non-communicating applications, any Lennox conventional thermostat may be used, as well as other non-communicating thermostats. . New York, NY 10036 In Canada, installation must conform with current National