Lennox MERIT Series Installation Instructions Manual
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Lennox MERIT Series Installation Instructions Manual

Downnflow air discharge
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© 2020 Lennox Industries Inc.
Dallas, Texas USA
Contents
Unit Dimensions - inches (mm) ......................................2
ML193DFE Gas Furnace................................................3
Shipping and Packing List ..............................................3
Safety .............................................................................3
General ...........................................................................5
Combustion, Dilution, Ventilation Air...............................5
Setting Equipment ..........................................................8
Filters ............................................................................12
Duct System .................................................................12
Pipe Fittings Specifications...........................................12
Joint Cementing Procedure ..........................................15
INSTALLATION
INSTRUCTIONS
ML193DFE
MERIT
SERIES GAS FURNACE
®
DOWNNFLOW AIR DISCHARGE
507865-02
06/2020
Supersedes 06/2019
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.
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.
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.
Venting Practices ..........................................................15
Gas Piping ....................................................................31
Electrical .......................................................................33
Unit Start-Up .................................................................37
Gas Pressure Measurement.........................................38
Proper Combustion.......................................................39
High Altitude .................................................................39
Other Unit Adjustments.................................................41
Service..........................................................................43
Repair Parts List ...........................................................44
Start Up Checklist .........................................................45
Blower Data ..................................................................48
Page 1
CAUTION
WARNING

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Summary of Contents for Lennox MERIT Series

  • Page 1: Table Of Contents

    INSTALLATION INSTRUCTIONS ML193DFE © 2020 Lennox Industries Inc. Dallas, Texas USA MERIT SERIES GAS FURNACE ® DOWNNFLOW AIR DISCHARGE 507865-02 06/2020 Supersedes 06/2019 THIS MANUAL MUST BE LEFT WITH THE HOMEOWNER FOR FUTURE REFERENCE This is a safety alert symbol and should never be ignored.

  • 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 OPENING on either side of unit. EXHAUST AIR (See installation instructions OUTLET for additional information.) 2-1/16 (52) 2-1/4 9/16 (14) (57)

  • Page 3: Ml193Dfe Gas Furnace

    ML193DFE Gas Furnace Shipping and Packing List The ML193DFE Category IV gas furnace is shipped ready Package 1 of 1 contains for installation in the downflow position. 1 - Assembled ML193DFE unit The furnace is equipped for installation in natural gas 1 - Bag assembly containing the following: applications.

  • Page 4: Use Of Furnace As A Construction Heater

    American National Standards Institute, Inc. 11 West 42nd Street New York, NY 10036 In Canada, installation must conform with current National Standard of Canada CSA-B149 Natural Gas and Propane AIR HANDLER GAS UNIT Installation Codes, local plumbing or waste water codes and other applicable local codes.

  • Page 5: General

    FAILURE TO FOLLOW THE ABOVE INSTALLATION IN- Chlorinated waxes and cleaners STRUCTIONS VOIDS THE MANUFACTURER’S EQUIP- Chlorine base swimming pool chemicals MENT LIMITED WARRANTY. LENNOX DISCLAIMS Water softening chemicals ALL LIABILITY IN CONNECTION WITH INSTALLER’S FAILURE TO FOLLOW THE ABOVE INSTALLATION IN- De-icing salts or chemicals STRUCTIONS.
  • Page 6 When the furnace is installed so that supply ducts carry CAUTION 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- tion, the confined space must have two permanent open- If air from outside is brought in for combustion and ventila- ings. One opening shall be within 12 inches (305 mm) of tion, the confined space shall be provided with two perma- the top of the enclosure and one opening within 12 inches nent openings.

  • Page 8: Setting Equipment

    Shipping Bolt Removal EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE (All Air Through Ventilated Attic) Units with 1/2 and 3/4 hp blower motor are equipped with three flexible legs and one rigid leg. The rigid leg is equipped with a shipping bolt and a flat white plastic wash- ROOF TERMINATED er (rather than the rubber mounting grommet used with VENTILATION LOUVERS...
  • Page 9 Allow for clearances to combustible materials as indicated SETTING EQUIPMENT on the unit nameplate. Minimum clearances for closet or alcove installations are shown in FIGURE 13. AIR FLOW AIR FLOW AIR FLOW WARNING Blower access panel must be securely in place when blower and burners are operating.
  • Page 10 Installation on Non-Combustible Flooring FIGURE 14 WARNING 1 - Cut floor opening keeping in mind clearances listed Improper installation of the furnace can result in personal on unit rating plate. Also keep in mind gas supply injury or death. Combustion and flue products must connections, electrical supply, flue and air intake never be allowed to enter the return air system or air connections and sufficient installation and servicing...
  • Page 11 TABLE 2 COMBUSTIBLE FLOORING BASE OPENING SIZE Front to Rear Side to Side Cabinet Catalog FURNACE Width Number B (17.5”) 11M60 18-3/4 C (21”) 11M61 22-3/4 COOLING COIL PROPERLY FURNACE SIZED FLOOR OPENING PLENUM SUPPLY AIR PLENUM PROPERLY COMBUSTIBLE SIZED FLOOR FLOORING BASE OPENING FIGURE 16...

  • Page 12: Filters

    Before using any filter with this system, check the specifications provided by the filter manufacturer against the data given in the appropriate Lennox Product FIGURE 19 Specifications bulletin. Additional information is provided...
  • Page 13 CAUTION IMPORTANT Solvent cements for plastic pipe are flammable liquids Exhaust and intake connections are made of PVC. Use and should be kept away from all sources of ignition. PVC primer and solvent cement when using PVC vent Do not use excessive amounts of solvent cement when pipe.

  • Page 14: Joint Cementing Procedure

    TABLE 5 OUTDOOR TERMINATION USAGE* STANDARD CONCENTRIC Wall Kit 1-1.2 inch 2 inch 3 inch Flush Mount Kit 2 inch 3 inch Vent Pipe 71M80 69M29 Input Size Field 60L46 (US) 51W11 22G44 Dia. in. (US) (US) 44J40 (US) Fabricated 44W93 (US) (US)

  • Page 15: Venting Practices

    CHIMNEY Vent Piping Guidelines OR GAS VENT (Check sizing NOTE - Lennox has approved the use of DuraVent® and for water heater only) Centrotherm manufactured vent pipe and terminations as an option to PVC. When using the PolyPro® by Du- raVent or InnoFlue®...
  • Page 16 Use the following steps in the Piping Size Process to cor- rectly size vent pipe diameter. Desired pipe size? NOTE - Lennox offers a glueless vent adapter kit 17H92 as an option for exhaust exiting at the furnace top cap coupling.
  • Page 17 TABLE 7 Maximum Allowable Intake or Exhaust Vent Length in Feet *Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust must be same pipe 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.
  • Page 18 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 of exhaust pipe. TRANSITION INTAKE EXHAUST DO NOT transition from smaller *2” to larger pipe size in horizontal TOP VIEW runs of exhaust pipe.
  • Page 19 Intake Piping 1 - Use field-provided materials and the factory-provided air intake screen to route the intake piping as shown The ML193DFE furnace may be installed in either Direct in FIGURE 25. Maintain a minimum clearance of Vent or Non-Direct Vent applications. In non-direct vent 3”...
  • Page 20 CSA-B149 Natural Gas and Propane Installation Codes in EQUIPMENT IN CONFINED SPACE Canada for details. (Inlet Air from Ventilated Crawlspace and Outlet Air to Outside) Position termination according to location given in FIG- URE 29 or FIGURE 30. In addition, position termination Roof Terminated so it is free from any obstructions and 12”...
  • Page 21 TABLE 9 Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For Winter Design Temperatures Single - Stage High Efficiency Furnace Winter Design Unit Input Size Vent Pipe Temperatures1 Diameter °F (°C) 1-1/2” 32 to 21 2 in (0 to -6) 2-1/2 in...
  • Page 22 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible. FIGURE 29...
  • Page 23 ‡ Permitted only if veranda, porch, deck or balcony is fully open on a minimum of two sides beneath the floor. Lennox recommends avoiding this location if possible. FIGURE 30 Page 23...
  • Page 24 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 25 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 EXHAUST 12” one bracket must be used within 6” from the top of (305mm) VENT the elbow and then every 24”...
  • Page 26 FIELD FABRICATED WALL TERMINATION NOTE − FIELD−PROVIDED REDUCER MAY BE 2” (51mm) 3” (76mm) REQUIRED TO ADAPT LARGER VENT PIPE SIZE Vent Pipe Vent Pipe TO TERMINATION A− Minimum clearance above grade or average 12” (305 mm) 12” (305 mm) snow accumulation B−...
  • Page 27 The termination pipe must be sized as listed in TABLE 10.The Specified pipe size ensures Lennox provides kit 51W18 to install 2” or 3” PVC exhaust proper velocity required to move the exhaust gases piping through the floor joists and into the crawl space.
  • Page 28 Condensate Piping 2 - Use a large flat head screw driver or a 1/2” drive socket extension and remove plug (figure 43) from the This unit is designed for either right- or left-side exit of cold end header box at the appropriate location on the condensate piping.
  • Page 29 Heat cable kit is avail- Do not use copper tubing or existing copper condensate able from Lennox in various lengths; 6 ft. (1.8m) - kit lines for drain line. no. 26K68 and 24 ft. (7.3m) - kit no. 26K69.
  • Page 30 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.

  • Page 31: 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 piping...
  • Page 32 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...

  • Page 33: Electrical

    Removal of the Furnace from Common Vent Resize the common venting system to the minimum vent pipe size determined by using the appropriate In the event that an existing furnace is removed from a tables in Appendix G. (These are in the current stan- venting system commonly run with separate gas applianc- dards of the National Fuel Gas Code ANSI Z223.1.
  • Page 34 Refer to FIGURE 53 for field wiring, schematic wiring dia- One line voltage 120V “HUM” 1/4” spade terminal is pro- gram and troubleshooting. vided on the furnace integrated control. See FIGURE 54 for integrated control configuration. This terminal is ener- The power supply wiring must meet Class I restrictions.
  • Page 35 FIGURE 53 Page 35...
  • Page 36 TABLE 12 Integrated Control 1/4” QUICK CONNECT TERMINALS INTEGRATED CONTROL 120HUM Humidifier 120VAC (Automatic Hot Surface Ignition System) LINE 120VAC XFMR Transformer 120VAC CIRC Indoor blower 120VAC Indoor air quality accessory 120VAC NEUTRAL Common 120VAC HUM24 Humidifier 24VAC 3/16” QUICK CONNECT TERMINALS COOL Cooling tap 24VAC HEAT...

  • Page 37: Unit Start-Up

    6 - Adjust the thermostat to deactivate the heating Unit Start Up demand and wait for the combustion air inducer to FOR YOUR SAFETY READ BEFORE OPERATING stop. At this point, the trap should be primed with sufficient water to ensure proper condensate drain WARNING operation.

  • Page 38: Gas Pressure Measurement

    Failure To Operate NOTE - To obtain accurate reading, shut off all other gas appliances connected to meter. If the unit fails to operate, check the following: Furnace should operate at least 5 minutes before check- 1 - Is the thermostat calling for heat? ing gas flow.

  • Page 39: 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 40: Testing Non Direct Appliances For Proper Air

    Horizontal pitch. Determine there is no blockage or Testing of Non-Direct Vent Applications for Proper restriction, leakage, corrosion, or other deficiencies Venting and Sufficient Combustion Air which could cause an unsafe condition. WARNING 3 - To the extent that it is practical, close all building doors and windows and all doors between the space in which the appliances connected to the venting .

  • Page 41: Other Unit Adjustments

    Other Unit Adjustments HEAT FAN OFF TIME IN SECONDS Primary Limit The primary limit is located on the heating compartment vestibule panel. This limit is factory set and requires no adjustment. NO JUMPER Flame Rollout Switches (Two) To adjust fan-off timing, reposition jumper across pins to achieve desired setting.
  • Page 42 At the beginning of each heating season, and to comply and operation. Consult Service Literature for proper with the Lennox Limited Warranty, your system should be combustion values. checked as follows: 14- Verify operation of CO detectors and replace 1 - Check wiring for loose connections, voltage at batteries as required.

  • Page 43: Service

    Winterizing and Condensate Trap Care Repair Parts List 1 - Turn off power to the furnace. The following repair parts are available through Lennox dealers. When ordering parts, include the complete fur- 2 - Have a shallow pan ready to empty condensate nace model number listed on the CSA nameplate -- Exam- water.
  • Page 44 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 45: Start Up Checklist

    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 46 4 - INSPECTION. The state or local gas inspector of the Requirements for Commonwealth of Massachusetts side wall, horizontally vented, gas-fueled equipment Modifications to NFPA-54, Chapter 10 shall not approve the installation unless, upon inspection, the inspector observes carbon monoxide Revise NFPA-54 section 10.8.3 to add the following detectors and signage installed in accordance with requirements:...
  • Page 47 FOR THE PROVINCE OF ONTARIO, HORIZONTAL SIDE- ADDENDUM FOR ALL PROVINCES OF CANADA WALL VENT APPLICATIONS ONLY See below for venting in all provinces of Canada. Lennox For exterior horizontal venting applications, the 2” X 1.5” approves the following termination for use in all provinces reducer for 2”...

  • Page 48: Blower Data

    Blower Data ML193DF045XE36B PERFORMANCE (Less Filter) Air Volume / Watts at Various Blower Speeds External High Medium-High Medium Medium-Low Static (Black) (Brown) (Blue) (Yellow) (Red) Pressure in. w.g. Watts Watts Watts Watts Watts 0.00 1430 1305 1180 0.10 1395 1270 1145 0.20 1365...

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Ml193dfeMerit ml193dfe seriesMerit ml193df045xe36bMerit ml193df070xe36bMerit ml193df090xe48cMerit ml193dfe

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