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© 2025 Lennox Industries Inc.
Dallas, Texas USA
WARNING
This furnace is equipped with an ignition control
factory enabled for use with Lennox A2L refrigerant
systems.
Disabling
functionality on A2L system is prohibited by safety
codes. Refer to furnace installation instructions for
non-A2L and non-Lennox refrigerant system setup.
Contents
Unit Dimensions - inches (mm) ......................................2
EL297DFEK Gas Furnace ..............................................3
Shipping and Packing List ..............................................3
Safety .............................................................................3
Use of Furnace as a Construction Heaterl .....................4
General ...........................................................................5
Combustion, Dilution, Ventilation Air...............................5
Setting Equipment ..........................................................8
Filters ............................................................................12
Duct System .................................................................12
Pipe Fittings Specifications...........................................12
Venting Options ............................................................13
Joint Cementing Procedure ..........................................16
Venting Practices ..........................................................16
the
refrigerant
detection
INSTALLATION
INSTRUCTIONS
EL297DFEK
ELITE
SERIES GAS FURNACE
®
DOWNFLOW AIR DISCHARGE
508579-01
01/2025
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be
ignored. When you see this symbol on labels or in man-
uals, be alert to the potential for personal injury or death.
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer (or
equivalent), service agency or the gas supplier.
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
Vent Pipe Guidleines ....................................................18
Gas Piping ....................................................................35
Electrical .......................................................................37
Ignition Control .............................................................39
Low GWP Application ...................................................48
Unit Start-Up .................................................................51
Gas Pressure Measurement.........................................52
Proper Combustion.......................................................53
High Altitude .................................................................53
Other Unit Adjustments.................................................55
Sequence of Operation.................................................55
Service..........................................................................56
Star-Up and Performance Checklist .............................58
Repair Parts List ...........................................................61
Page 1
WARNING
CAUTION
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Summary of Contents for Lennox ELITE EL297DFEK
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Page 1: Table Of Contents
Take care while handling this equipment and wear gloves and This furnace is equipped with an ignition control protective clothing. factory enabled for use with Lennox A2L refrigerant systems. Disabling refrigerant detection functionality on A2L system is prohibited by safety codes. -
Page 2: Unit Dimensions - Inches (Mm)
Unit Dimensions - inches (mm) 9/16 (14) Flue Condensate Trap Assembly COMBUSTION AIR INTAKE Furnished for external field installation (178) RETURN AIR on either side of unit. OPENING EXHAUST AIR (See installation instructions OUTLET for additional information.) 2-1/16 (52) 2-1/4 9/16 (14) (57) -
Page 3: El297Dfek Gas Furnace
EL297DFEK Gas Furnace Shipping and Packing List Package 1 of 1 contains The EL297DFEK Category IV gas furnace is shipped ready for installation in the downflow position. 1 - Assembled EL297DFEK unit The furnace is equipped for installation in natural gas 1 - Bag assembly containing the following: applications. -
Page 4: Building Codes
Building Codes In Canada, all electrical wiring and grounding for the unit must be installed according to the current regulations of In the USA, installation of gas furnaces must conform with the Canadian Electrical Code Part I (CSA Standard C22.1) local building codes. -
Page 5: General
FAILURE TO FOLLOW THE ABOVE INSTALLATION IN- Chlorine base swimming pool chemicals STRUCTIONS VOIDS THE MANUFACTURER’S EQUIP- Water softening chemicals MENT LIMITED WARRANTY. LENNOX DISCLAIMS De-icing salts or chemicals ALL LIABILITY IN CONNECTION WITH INSTALLER’S FAILURE TO FOLLOW THE ABOVE INSTALLATION IN- Carbon tetrachloride STRUCTIONS. -
Page 6: Unconfined Space
When the furnace is installed so that supply ducts carry DANGER air circulated by the furnace to areas outside the space containing the furnace, the return air must be handled by Do not install the furnace in a corrosive or contaminated ducts which are sealed to the furnace casing and which atmosphere. - Page 7 Air from Outside If air from outside is brought in for combustion and ventila- EQUIPMENT IN CONFINED SPACE (Inlet Air from Ventilated Crawlspace and Outlet Air to Outside) tion, the confined space shall be provided with two perma- nent openings. One opening shall be within 12” (305mm) of the top of the enclosure and one within 12”...
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Page 8: Installation - Setting Equipment
Installation - Setting Equipment EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE WARNING ROOF TERMINATED Do not install the furnace on its front, back or in the EXHAUST PIPE horizontal position. See FIGURE 12. Do not connect the return air ducts to the back of the furnace. Doing so OUTLET AIR will adversely affect the operation of the safety control devices, which could result in personal injury or death. - Page 9 Front Back Horizontal NOTE - Do not install the furnace on its front, back or in the horizontal position FIGURE 12 WARNING Improper installation of the furnace can result in personal injury or death. Combustion and flue products must never be allowed to enter the return air system or air in the living space.
- Page 10 The unit may be installed three ways in downflow applica- TABLE 1 tions: on non-combustible flooring, on combustible floor- NON-COMBUSTIBLE FLOOR OPENING SIZE ing using an additive base, or on a reverse-flow cooling coil cabinet. Do not drag the unit across the floor in the Front to Rear Side to Side Cabinet...
- Page 11 FURNACE FURNACE SUPPLY AIR PLENUM PROPERLY COMBUSTIBLE SIZED FLOOR FLOORING BASE COOLING COIL OPENING PROPERLY SIZED FLOOR OPENING PLENUM FIGURE 15 TABLE 2 FIGURE 16 COMBUSTIBLE FLOORING BASE OPENING SIZE Return Air Opening -- Downflow Units Front to Rear Side to Side Cabinet Catalog Return air may be brought in only through the top opening...
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Page 12: Filters
Lennox Product bustion and the formation of carbon monoxide gas. This Specifications bulletin. Additional information is provided... -
Page 13: Specification
Use PVC primer and solvent cement or ABS solvent ce- TABLE 4 ment meeting ASTM specifications, refer to TABLE 4. As PIPING AND FITTINGS SPECIFICATIONS an alternate, use all purpose cement, to bond ABS, PVC, or CPVC pipe when using fittings and pipe made of the Schedule 40 PVC (Pipe) D1785 same materials. - Page 14 Failure to use gaskets and plates may lead to improper Lennox provides kit 51W18 (USA) and kit 15Z70 (Cana- operation of unit. da) to install 2” or 3” PVC exhaust piping through the floor joists and into the the crawl space.
- Page 15 Right Side Vent Configuration Side Vent Sealing Plate Side Vent Sealing Gaskets Exhaust Intake Street Elbows (2) FIGURE 23 TABLE 5 OUTDOOR TERMINATION USAGE* STANDARD CONCENTRIC Flush Mount Wall Kit 1-1/2 inch 2 inch 3 inch Vent Pipe Input Size 2 inch 3 inch Field...
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Page 16: Joint Cementing Procedure
Joint Cementing Procedure Venting Practices All cementing of joints should be done according to the specifications outlined in ASTM D 2855. HORIZONTAL PIPING SUPPORT GUIDELINES NOTE - A sheet metal screw may be used to secure the SCHEDULE 40 intake pipe to the connector, if desired. Use a drill or self PVC - 5' tapping screw to make a pilot hole. - Page 17 2 - When furnace is installed in a residence where unit 4 - Follow the lighting instructions. Turn on the appliance is shut down for an extended period of time, such that is being inspected. Adjust the thermostat so that as a vacation home, make provisions for draining the appliance operates continuously.
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Page 18: Vent Piping Guidelines
Doing so will cause freeze-ups and FIGURE 26 may block the terminations. NOTE - Lennox offers a glueless vent adapter kit 17H92 NOTE - It is acceptable to use any pipe size which fits as an option for exhaust exiting at the furnace top cap coupling. - Page 19 TABLE 7 Maximum Allowable Intake or Exhaust Vent Length Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Intake and Exhaust must be same size. NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation. Standard Termination at Elevation 0 - 4500 ft Number 1-1/2”...
- Page 20 TABLE 7 Continued Maximum Allowable Intake or Exhaust Vent Length Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Intake and Exhaust must be same size. NOTE - Additional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation. Concentric Termination at Elevation 0 - 4500 ft Number 1-1/2”...
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Page 21: Top View
TYPICAL EXHAUST PIPE CONNECTIONS 045/070 Only 2” 1−1/2” 2” 2” 2” TRANSITION 2” 2” Exhaust Exhaust 3” DO NOT transition from larger to smaller pipe in horizontal runs TRANSITION of exhaust pipe. INTAKE EXHAUST DO NOT transition from smaller *2” to larger pipe size in horizontal TOP VIEW runs of exhaust pipe. - Page 22 TYPICAL EXHAUST CONNECTIONS WITH RIGHT SIDE VENT OPTION Pipe Length 4” Maximum (Not Furnished) 3” 2” 2” TRANSITION *2” 2” Plate (Furnished) Street Ell (Not Furnished) TOP VIEW * When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible. NOTE Intake pipe and exhaust pipe must be the same diameter.
- Page 23 Intake Piping EQUIPMENT IN CONFINED SPACE The EL297DFEK furnace may be installed in either direct (Inlet Air from Ventilated Crawlspace and Outlet Air to Outside) vent or non-direct vent applications. In non-direct vent applications, when intake air will be drawn into the furnace Roof Terminated from the surrounding space, the indoor air quality must be Exhaust Pipe...
- Page 24 In both Non-Direct Vent and Direct Vent applications, the vent termination is limited by local building codes. In the TYPICAL AIR INTAKE PIPE CONNECTIONS absence of local codes, refer to the current National Fuel NON−DIRECT VENT APPLICATIONS Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current CSA-B149 Natural Gas and Propane Installation Codes in INTAKE SCREEN...
- Page 25 TABLE 9 Maximum Allowable Exhaust Vent Pipe Length (in ft. ) Without Insulation In Unconditioned Space For Winter Design Temperatures Two - Stage High Efficiency Furnace Vent Pipe Unit Input Size Winter Design Temperatures1 °F (°C) Diameter 1-1/2 in 32 to 21 2 in (0 to -6) 2-1/2 in...
- Page 26 ‡ Permitted only if veranda, porch, deck or balcony is fully open NOTE - This figure is intended to illustrate clearance on a minimum of two sides beneath the floor. Lennox recommends requirement and does not serve as a substitute for avoiding this location if possible.
- Page 27 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of locally adopted installation codes. two sides beneath the floor. Lennox recommends avoiding this location if possible. FIGURE 36 Page 27...
- Page 28 Details of Intake and Exhaust Piping Terminations for 6 - On field supplied terminations, a minimum distance Direct Vent Installations between the end of the exhaust pipe and the end of the intake pipe without a termination elbow is 8” and NOTE - In Direct Vent installations, combustion air is taken a minimum distance of 6”...
- Page 29 7 - If intake and exhaust piping must be run up a side wall to position above snow accumulation or other obstructions, piping must be supported. At least 12” EXHAUST one bracket must be used within 6” from the top of (305mm) VENT 5-1/2”...
- Page 30 FIELD FABRICATED WALL TERMINATION NOTE − FIELD−PROVIDED REDUCER MAY BE 2” (51mm) 3” (76mm) REQUIRED TO ADAPT Vent Pipe Vent Pipe LARGER VENT PIPE SIZE TO TERMINATION A− Minimum clearance above grade or average 12” (305 mm) 12” (305 mm) snow accumulation B−...
- Page 31 Details of Exhaust Piping Terminations for Non-Direct Vent Applications 12” (305mm) ABOVE AVE. Exhaust pipes may be routed either horizontally through SNOW an outside wall or vertically through the roof. In attic or ACCUMULATION closet installations, vertical termination through the roof is preferred.
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Page 32: Condensate Trap Location
If this is not possible, a heat cable kit may be used on the condensate trap and line. Heat cable kit is avail- able from Lennox in various lengths; 6 ft. (1.8m) - kit to drain no. 26K68 and 24 ft. (7.3m) - kit no. 26K69. - Page 33 Condensate Trap With Optional Overflow Switch Furnace with Evaporator Coil Using a Separate Drain From Evaporator Coil HorizontalFurnace4” Min. to 5” Max.above condensatedrain connection) Field Provided Vent 1” min. 2” max. above condensate drain. FurnaceCondensate Condensate DrainConnection Drain Connection Optional Evaporator Drain Line (vent required) Drain...
- Page 34 TRAP / DRAIN ASSEMBLY USING 1/2” PVC OR 3/4” PVC Optional Condensate Drain Connection Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) 90° Street Elbow 3/4 inch PVC (not furnished) Adapter 3/4 inch slip X 3/4 inch mpt (not furnished) Condensate Drain Connection In Unit 1 (25 mm) Min.
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Page 35: Gas Piping
IMPORTANT Gas Piping CAUTION Compounds used on threaded joints of gas piping must be resistant to the actions of liquified petroleum gases. If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be Leak Check installed at the gas valve and extend outside the furnace After gas piping is completed, carefully check all field-in-... - Page 36 Left Side Piping AUTOMATIC MANUAL (Standard) GAS VALVE MAIN SHUT-OFF MANUAL (with manual VALVE AUTOMATIC MAIN SHUT-OFF shut-off valve) (1/8 in. NPT GAS VALVE VALVE plugged tap (with manual (1/8 in. NPT shown) shut-off valve) plugged tap shown) GROUND JOINT UNION GROUND JOINT...
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Page 37: Electrical
IMPORTANT Electrical WARNING When matching this gas furnace with zoning, defrost tempering stat or other 24V accessories, Electric Shock Hazard. Can cause injury or It is recommended to replace the factory installed death. Unit must be properly grounded in transformer with kit 27J32. accordance with national and local codes. - Page 38 Indoor Blower Speeds On-Board Link W914 Dehum 1 - When the thermostat is set to “FAN ON,” the indoor On-board link W914, is a clippable connection between blower will run continuously on the field selectable terminals R and DS on the integrated control. W914 must fan speed (“LOW HEAT”...
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Page 39: Ignition Control
Ignition Control TWO STAGE CONSTANT TORQUE, NON-COMMUNICATING 107897-01 FIGURE 58 TABLE 13 TABLE 12 THERMOSTAT INPUT TERMINALS 1/4” QUICK CONNECT TERMINALS LOW STAGE HEAT 120V HUM POWER FOR HUMIDIFIER (120 VAC HIGH STAGE HEAT LINE INCOMING POWER LINE (120 VAC) XFMR TRANSFORMER PRIMARY (120 VAC) LOW STAGE COOL (when W915 is clipped) - Page 40 Ignition Control Diagnostics Codes DIAGNOSTIC CODES / STATUS OF FURNACE CODE IDLE MODE (DECIMALBLINKS AT 1 HERTZ -- 0.5 SECONDS ON, 0.5 SECONDS OFF INDOOR BLOWER OPERATION: CONTINUOUS FAN MODE (COSTANT TORQUE ONLY) INDOOR BLOWER OPERATION: FOLLOWED BY CFM SETTING FOR INDOOR BLOWER (1 SECOND ON, 0.5 SECOND OFF) / CFM SETTING FOR MODE DISPLAYED (VARIALBE SPEED ONLY) COOLING STAGE (1 SECOND ON, 0.5 SECOND OFF) 1 OR 2 DISPLAYED / PAUSE / REPEAT CODES.
- Page 41 Ignition Control Diagnostic Codes (continued) SOFT LOCKOUT FAULTS (60 MINUTES) GAS VALVE RELAY (1ST OR 2ND STAGE) CONTACT SHORTED E205 HOT SURFACE IGNITOR (HSI) SENSED OPEN E207 SOFT LOCKOUT-FLAME FAILURE ON IGNITION, IGNITION RETRY>MAX, LAST FAILED RETRY DUE TO FLAME E270 FAILURE SOFT LOCKOUT-PRESSURE SWITCH OPEN, IGNITION RETRY>MAX, LAST FAILED RETRY DUE TO LPSW OPEN...
- Page 42 The blower off delay affects comfort and is adjustable to Ignition Control DIP Switch Settings satisfy individual applications. Adjust the blower off de- EL297DFEK units are equipped with a two-stage integrat- lay to achieve a supply air temperature between 90° and ed control.
- Page 43 DIP Switch Settings and On-Board Links DIP Switch 1 On Board Links Must Be Cut To Select Thermostat Thermostat Wiring Connections System Options TABLE 18 Heating EL297DFEK Field Wiring Applications With Conventional Thermostat Stages 1 Heat / 1 Cool FURNACE OUTDOOR T'STAT TERM.
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Page 44: Wiring Connections
TABLE 18 EL297DFEK Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 On Board Links Must Be Cut To Select Thermostat Thermostat Wiring Connections System Options Heating Stages 2 Heat / 2 Cool FURNACE OUTDOOR (M30 T-stat) T'STAT... - Page 45 TABLE 18 EL297DFEK Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 Thermostat On Board Links Must Be Cut To Select Wiring Connections Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP T'STAT TERM.
- Page 46 TABLE 18 EL297DFEK Field Wiring Applications With Conventional Thermostat DIP Switch Settings and On-Board Links DIP Switch 1 Wiring Connections Thermostat On Board Links Must Be Cut To Select Thermostat Heating System Options Stages Dual Fuel FURNACE HEAT PUMP T'STAT TERM.
- Page 47 Wiring Diagram FIGURE 59 Page 47...
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Page 48: Low Gwp Application
Low GWP Application WARNING For use with Lennox approved evaporator coil and LGWP sensors only. Use original manufacturer recommended LGWP sensors if using non Lennox approved evaporator coil. CONNECTING THE FURNACE CONTROL BOARD SENSOR. See FIGURE 62 and follow steps below: 1 - Route sensor wire #1 through provided grommet. - Page 49 FURNACE CONTROL BOARD LOW GWP MODES OF NOTE - The HVAC system may not maintain a cooling or heating setpoint if a significant leak exists. Any refrigerant OPERATION leaks that remain unaddressed for an extended time may The modes of operation for the furnace control board are cause the HVAC system to shut down on a low refrigerant Initializing, Normal, Leak Detected, and Fault.
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Page 50: Start-Up Procedure
LGWP TEST BUTTON FUNCTIONALITY External Alarm (For applications with external alarms wired directly to the The furnace control board is equipped with a Test/Reset furnace control board) push button. The Test button can be used to perform sev- The furnace control board triggers the external alarm sys- eral functions, depending on the mode of operation of the tem when it enters Leak Detected mode. -
Page 51: Unit Start-Up
WARNING Unit Start-Up FOR YOUR SAFETY READ BEFORE OPERATING If you do not follow these instructions exactly, a fire or WARNING explosion may result causing property damage, personal injury or death. Do not use this furnace if any part has been underwater. A flood-damaged furnace is extremely dangerous. -
Page 52: Supply Pressure Measurement
Gas Flow (Approximate) NOTE - Pressure test adapter kit (10L34) is available from Lennox to facilitate manifold pressure measurement. TABLE 22 1 - Connect the test gauge positive side “+“ to manifold GAS METER CLOCKING CHART pressure tap on gas valve as noted above. -
Page 53: Proper Combustion
Proper Combustion High Altitude Information Furnace should operate minimum 15 minutes with correct NOTE - In Canada, certification for installations at eleva- manifold pressure and gas flow rate before checking com- tions over 4500 feet (1372 m) is the jurisdiction of local bustion. - Page 54 Testing of Non-Direct Vent Applications for Proper Venting and Sufficient Combustion Air 3 - To the extent that it is practical, close all building WARNING doors and windows and all doors between the space in which the appliances connected to the venting CARBON MONOXIDE POISONING HAZARD! system are located and other spaces of the building.
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Page 55: Other Unit Adjustments
Applications Using a Two-Stage Thermostat Other Unit Adjustments A - Heating Sequence -- Integrated Control Thermo- NOTE - See troubleshooting flow charts if any safety stat Selection DIP Switch 1 OFF in “Two-Stage” Posi- switches are found to be open. tion (Factory Setting) Primary Limit 1 - On a call for heat, thermostat first-stage contacts... -
Page 56: Service
At the beginning of each heating season, and to comply tion the unit will switch to low fire. with the Lennox Limited Warranty, your system should 3 - After the pre-purge is complete, a 20-second initial be checked as follows: ignitor warm-up period begins. - Page 57 8- Evaluate the heat exchanger integrity by inspecting Winterizing and Condensate Trap Care the heat exchanger per the AHRI heat exchanger 1 - Turn off power to the furnace. inspection procedure. This procedure can be viewed 2 - Have a shallow pan ready to empty condensate at www.ahrinet.org water.
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Page 58: Unit Setup
Start-Up & Performance Check List UNIT SET UP (typical) Furnace: Model Number_______________ Serial Number_________________ SUPPLY Line Voltage GAS SUPPLY LP Propane Gas Natural Gas Piping Connections Tight Leak Tested Flter Supply Line Pressure “W.C.________ RETURN AIR Gas Supply Pressure DUCT SYSTEM SUPPLY AIR DUCT Sealed INTAKE / EXHAUST PIPE... -
Page 59: Unit Operation
UNIT OPERATION HEATING MODE COOLING MODE GAS MANIFOLD PRESSURE “W.C._____ INDOOR BLOWER AMPS______ COMBUSTION SAMPLE CO CO PPM_______ TEMPERATURE DROP ______ Return Duct Temperature _________ INDOOR BLOWER AMPS______ Supply Duct Temperature _______ Temperature Drop = _________ TEMPERATURE RISE TOTAL EXTERNAL STATIC (dry coil) Supply Duct Temperature ________ Supply External Static _______ Return Duct Temperature... -
Page 60: Approved Carbon Monoxide Detectors
Requirements for Commonwealth of Massachusetts 4 - INSPECTION. The state or local gas inspector of the Modifications to NFPA-54, Chapter 10 side wall, horizontally vented, gas-fueled equipment Revise NFPA-54 section 10.8.3 to add the following shall not approve the installation unless, upon requirements: inspection, the inspector observes carbon monoxide For all side wall, horizontally vented, gas-fueled equip-... -
Page 61: Repair Parts List
Top Cap Addendum For All Porvinces Of Canada Control Panel Parts See below for venting in all provinces of Canada. Lennox Transformer approves the following termination for use in all provices Integrated control board of Canada. - Page 62 12” 2” (51MM) 3” (76MM) Vent Pipe Vent Pipe A − Clearance above grade or 12” (305 mm) Min. 12” (305 mm) Min. average snow accumulation 6” (152 mm) Min. 6” (152 mm) Min. B − Horizontal separation between 24” (610 mm) Max. 24”...
- Page 63 TABLE 26 Allowable Heating Speeds EL297DFEK Low Fire Heating Speeds High Fire Heating Speeds Model Yellow Blue Brown Black Yellow Blue Brown Black Number 045XE36B Allowed 070XE48B Factory Allowed Allowed Allowed Allowed Allowed Setting Allowed Allowed Allowed lowed 090XE48C 110XE60C Allowed TABLE 27 Allowable Circulation Speeds...
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