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

Downflow air discharge
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2019 Lennox Industries Inc.
©
Dallas, Texas USA
Contents
Unit Dimensions - inches (mm) ......................................2
ML195DF Gas Furnace ..................................................3
Shipping and Packing List ..............................................3
Safety .............................................................................3
General ...........................................................................5
Combustion, Dilution, Ventilation Air...............................5
Setting Equipment ..........................................................8
Filters ............................................................................ 11
Duct System ................................................................. 11
Pipe Fittings Specifications...........................................12
Joint Cementing Procedure ..........................................14
Venting Practices ..........................................................14
INSTALLATION
INSTRUCTIONS
ML195DF
MERIT
SERIES GAS FURNACE
®
DOWNFLOW AIRDISCHARGE
507269-03
02/2019
Supersedes 07/2018
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 Guidlines ......................................................15
Gas Piping ....................................................................32
Electrical .......................................................................34
Integrated Control .........................................................41
Unit Start-Up .................................................................38
Gas Pressure Measurement.........................................39
Proper Combustion.......................................................40
High Altitude .................................................................40
Testing Non Direct Applications for Proper Air ..............41
Repair Parts Lsit ...........................................................41
Other Unit Adjustmens..................................................42
Service..........................................................................42
Twinning .......................................................................44
Start-Up Checklist.........................................................44
Page 1
WARNING
CAUTION

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Summary of Contents for Lennox MERIT Series

  • Page 1: Table Of Contents

    INSTALLATION INSTRUCTIONS ML195DF 2019 Lennox Industries Inc. © Dallas, Texas USA MERIT SERIES GAS FURNACE ® DOWNFLOW AIRDISCHARGE 507269-03 02/2019 Supersedes 07/2018 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 RETURN AIR (178) on either side of unit. OPENING EXHAUST AIR (See installation OUTLET instructions for O U T additional information.) 2-1/16 (52) 9/16 2-1/4...

  • Page 3: Ml195Df Gas Furnace

    ML195DF Gas Furnace Shipping and Packing List Package 1 of 1 contains The ML195DF Category IV gas furnace is shipped ready for installation in the downflow position. 1 - Assembled ML195DF 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 Heaterl

    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 Installation Codes, local plumbing or waste water codes AIR HANDLER GAS UNIT and other applicable local codes.

  • Page 5: General

    FAILURE TO FOLLOW THE ABOVE INSTALLATION IN- De-icing salts or chemicals STRUCTIONS VOIDS THE MANUFACTURER’S EQUIP- Carbon tetrachloride MENT LIMITED WARRANTY. LENNOX DISCLAIMS ALL LIABILITY IN CONNECTION WITH INSTALLER’S Halogen type refrigerants FAILURE TO FOLLOW THE ABOVE INSTALLATION IN- Cleaning solvents (such as perchloroethylene) STRUCTIONS.
  • Page 6 A portion of this information has been reprinted with per- Confined Space mission from the National Fuel Gas Code (ANSI Z223.1/ A confined space is an area with a volume less than 50 NFPA 54). This reprinted material is not the complete and cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of official position of the ANSI on the referenced subject, the combined input rating of all appliances installed in that...
  • Page 7 Air from Outside EQUIPMENT IN CONFINED SPACE (Inlet Air from Ventilated Crawlspace and Outlet Air to Outside) If air from outside is brought in for combustion and ven- tilation, in the confined space shall be provided with two permanent openings. One opening shall be within 12” Roof Terminated Exhaust Pipe (305mm) of the top of the enclosure and one within 12”...

  • Page 8: Setting Equipment

    Blower motor with three exible legs and one EQUIPMENT IN CONFINED SPACE - ALL AIR FROM OUTSIDE rigid shipping leg. Blower motor housings (All Air Through Ventilated Attic) will be tagged for shipping bolt removal RIGID LEG (Remove shipping bolt ROOF TERMINATED VENTILATION LOUVERS and washer)
  • Page 9 Front Back Horizontal NOTE - Do not install the furnace on its front, back or in the horizontal position FIGURE 12 WARNING Downflow Application Installation Clearances 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 Installation on Non-Combustible Flooring Figure 14 TABLE 2 1 - Cut floor opening keeping in mind clearances listed COMBUSTIBLE FLOORING BASE OPENING SIZE on unit rating plate. Also keep in mind gas supply Front to Rear Side to Side Cabinet Catalog connections, electrical supply, flue and air intake Width...

  • Page 11: Filters

    Before using any filter with this system, check the specifications provided by the filter manufacturer against FIGURE 16 the data given in the appropriate Lennox Product Return Air Opening -- Downflow Units Specifications bulletin. Additional information is provided Return air may be brought in only through the top opening in Service and Application Note ACC002 (August 2000).

  • Page 12: Pipe Fittings Specifications

    TABLE 4 Duct Installation Down-Flow Unit PIPING AND FITTINGS SPECIFICATIONS Schedule 40 PVC (Pipe) D1785 Schedule 40 PVC (Cellular Core Pipe) F891 Schedule 40 PVC (Fittings) D2466 Schedule 40 CPVC (Pipe) F441 Schedule 40 CPVC (Fittings) F438 SDR-21 PVC or SDR-26 PVC (Pipe) D2241 SDR-21 CPVC or SDR-26 CPVC (Pipe) F442...
  • Page 13 Canadian Applications Only - Pipe, fittings, primer and solvent cement used to vent (exhaust) this appliance must be certified to ULC S636 and supplied by a single manufacturer as part of an approved vent (exhaust) system. In addition, the first three feet of vent pipe from the furnace flue collar must be accessible for inspection. TABLE 5 OUTDOOR TERMINATION USAGE* STANDARD...

  • Page 14: Joint Cementing Procedure

    Joint Cementing Procedure Venting Practices All cementing of joints should be done according to the Piping Suspension Guidelines specifications outlined in ASTM D 2855. 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 15 3 - Close all building doors and windows and all doors between the space in which the appliances NOTE - Lennox has approved the use of DuraVent® and remaining connected to the common venting system Centrotherm manufactured vent pipe and terminations are located and other spaces of the building.
  • Page 16 Doing so will cause freeze-ups and may block the terminations. Desired pipe size? NOTE - Lennox offers a glueless vent adapter kit 17H92 2”, 2-1/2”, 3” as an option for exhaust exiting at the furnace top cap coupling.
  • Page 17 TABLE 7 NOTE - 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 TABLE 7 Continued NOTE - 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 - dditional vent pipe and elbows used to terminate the vent pipe outside the structure must be included in the total vent length calculation.
  • Page 19 TABLE 8 Maximum Allowable Exhaust Vent Lengths With Furnace Installed in a Closet or Basement Using Ventilated Attic or Crawl Space For Intake Air in Feet 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 20 TYPICAL EXHAUST PIPE CONNECTIONS 2” 2” 2” 2” 2” 3” TRANSITION INTAKE EXHAUST DO NOT transition from smaller *2” to larger pipe size in horizontal TOP VIEW runs of exhaust pipe. * When transitioning up in pipe size, use the shortest length of 2” PVC pipe possible. NOTE −...
  • Page 21 Intake Piping 1 - Use field-provided materials and the factory- provided air intake screen to route the intake piping The ML195DF furnace may be installed in either direct as shown in figure 25. Maintain a minimum clearance vent or non-direct vent applications. In non-direct vent ap- of 3”...
  • Page 22 Gas Code ANSI Z223-1/NFPA 54 in U.S.A., and current EQUIPMENT IN CONFINED SPACE CSA-B149 Natural Gas and Propane Installation Codes in (Inlet Air from Ventilated Crawlspace and Outlet Air to Outside) Canada for details. Position termination according to location given in figure Roof Terminated 29 or 30.

  • Page 23: Vent Pipe Guidlines

    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 °F Diameter (°C) 32 to 21 2 in (0 to -6) 2-1/2 in 3 in...
  • Page 24 ‡ 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 25 ‡ 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 25...
  • Page 26 Details of Intake and Exhaust Piping Terminations for NOTE - Care must be taken to avoid recirculation of Direct Vent Installations exhaust back into intake pipe. 6 - On field supplied terminations, a minimum distance NOTE - In Direct Vent installations, combustion air is taken between the end of the exhaust pipe and the end of from outdoors and flue gases are discharged to outdoors.
  • Page 27 7 - If intake and exhaust piping must be run up a side wall to position above snow accumulation or other FIELD-PROVIDED obstructions, piping must be supported. At least one QUIRED TO ADAPT bracket must be used within 6” from the top of the LARGER VENT PIPE SIZE TO TERMINATION.
  • Page 28 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 29 10.The specified pipe size ensures proper velocity required to move the exhaust gases away Lennox provides kit 51W18 (USA) and kit 15Z70 (Cana- from the building. da) to install 2” or 3” PVC exhaust piping through the floor 2 - On field supplied terminations for side wall exit, joists and into the the crawl space.
  • Page 30 Heat cable kit is avail- ry installed. Check the unused plug for tightness to able from Lennox in various lengths; 6 ft. (1.8m) - kit prevent leakage. no. 26K68 and 24 ft. (7.3m) - kit no. 26K69.
  • Page 31 Furnace with Evaporator CONDENSATE TRAP LOCATION Coil Using a Common Drain (shown with right side exit of condensation) Field Provided Vent 1” min. 2” max. above condensate drain. Trap can be installed a maximum of 5ft. from furnace (*PVC only) Condensate Field Provided Vent Drain Connection...
  • Page 32 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 33: 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 Leak Check authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace After gas piping is completed, carefully check all piping cabinet.
  • Page 34 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 35: Electrical

    Removal of the Furnace from Common Vent Electrical In the event that an existing furnace is removed from a ELECTROSTATIC DISCHARGE (ESD) venting system commonly run with separate gas applianc- Precautions and Procedures es, the venting system is likely to be too large to properly CAUTION vent the remaining attached appliances.
  • Page 36 Refer to figure 53 for field wiring, schematic wiring dia- Indoor Blower Speeds gram and troubleshooting. 1 - When the thermostat is set to “FAN ON,” the indoor The power supply wiring must meet Class I restrictions. blower will run continuously on the heating speed Protected by either a fuse or circuit breaker, select circuit when there is no cooling or heating demand.
  • Page 37 TYPICAL ML195DF WIRING DIAGRAM FIGURE 53 Page 37...

  • Page 38: Integrated Control

    INTEGRATED CONTROL (Automatic Hot Surface Ignition System) TERMINAL DESIGNATIONS Humidifier (120VAC) Input (120VAC) LINE Transformer (120VAC) XFMR Indoor Air Qality Accessory Air Cleaner (120VAC) Blower - Cooling Speed (120VAC) COOL Blower - Heating Speed (120VAC) HEAT Dead terminals to park alternate spd taps PARK Continuous blower CONT...

  • Page 39: 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 40 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 41: 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 42: Repair Parts Lsit

    Repair Parts List The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA nameplate -- Example: ML195DF045XP36B. All service must be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.

  • Page 43: Other Unit Adjustmens

    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. Flame Rollout Switches (Two) NO JUMPER To adjust fan-off timing, reposition jumper across pins to These manually reset switches are located on the front of achieve desired setting.
  • Page 44 At the beginning of each heating season, and to comply 1 - Check the operation of the ignition system, inspect with the Lennox Limited Warranty, your system should be and clean flame sensor. Check microamps before checked as follows: and after.

  • Page 45: Twinning

    8 - Reconnect the sensor wire and reconnect the 2-pin Each furnace must be wired with a dedicated line voltage plug to the ignitor wiring harness. supply. However, both circuits must be connected to the same buss in the main distribution panel. 9 - Reinstall the burner box assembly using the existing four screws.
  • Page 46 Start-Up & Performance Check List UNIT SET UP 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 Insulated (if necessary)
  • Page 47 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 48 Start-Up & Performance Check List Modifications to NFPA-54, Chapter 10 4 - INSPECTION. The state or local gas inspector of the 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 49 ADDENDUM FOR THE PROVINCE OF SASKATCHEWAN AND MANITOBA See below for venting in the province of Saskatchewan and Manitoba.. Lennox approves the following termination for use in Saskatchewan and Manitoba Canada. 12”...

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