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Lennox ML196DF045XE36B Manual

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Service Literature
ML196DFE series units are high-efficiency gas fur­
naces manufactured with Lennox DuralokPlust alumi­
nized steel clamshell-type heat exchangers, with a stainless
steel condensing coil. ML196DFE units are available in
heating input capacities of 44,000 to 110,000 Btuh and
cooling applications from 2 through 5 tons. Refer to Product
Specifications for proper sizing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LP/Propane operation. All
ML196DFE units are equipped with a hot surface ignition
system. The gas valve is redundant to assure safety
shut-off as required by C.S.A.
The heat exchanger, burners and manifold assembly can be
removed for inspection and service. The maintenance section
gives a detailed description on how this is done.
All specifications are subject to change. Procedures outlined
in this manual are presented as a recommendation only
and do not supersede or replace local or state codes.
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon­
nect switch(es). Unit may have multiple
power supplies.

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Corp. 1910-L7
02/2021
ML196DFE SERIES UNITS
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Improper installation, adjustment, alteration, service
3
or maintenance can cause property damage, person­
al injury or loss of life. Installation and service must
4
be performed by a licensed professional HVAC in­
5
staller (or equivalent), service agency or the gas sup­
19
plier.
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As with any mechanical equipment, contact with
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sharp sheet metal edges can result in personal in­
48
jury. Take care while handling this equipment and
wear gloves and protective clothing.
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Page 1
ML196DFE
WARNING
CAUTION
© 2021 Lennox Industries Inc.
Litho U.S.A.

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Summary of Contents for Lennox ML196DF045XE36B

  • Page 1: Table Of Contents

    Service Literature ML196DFE SERIES UNITS ML196DFE series units are high-efficiency gas fur­ naces manufactured with Lennox DuralokPlust alumi­ nized steel clamshell-type heat exchangers, with a stainless steel condensing coil. ML196DFE units are available in heating input capacities of 44,000 to 110,000 Btuh and cooling applications from 2 through 5 tons.

  • Page 2: Specifications

    SP ECIF ICATIONS Model No. ML196DF045XE36B ML196DF070XE48B ML196DF090XE48C ML196DF110XE60C Heating AFUE Performance Input - Btuh 44,000 66,000 88,000 110,000 Output - Btuh 42,000 64,000 85,000 106,000 Temperature rise range - °F 30 - 60 35 - 65 50 - 80 40 - 70 Gas Manifold Pressure (in.

  • Page 3: Optional Accessories

    OPT IONAL AC C ESSORIES “B” Width Models “C” Width Models CABINET ACCESSORIES Downflow Combustible Flooring Base 11M60 11M61 CONDENSATE DRAIN KITS Condensate Drain Heat Cable 26K68 26K68 6 ft. 26K69 26K69 24 ft. Crawl Space Vent Drain Kit 51W18 51W18 Canada 15Z70...

  • Page 4: Blower Performance Data

    BLO WER DATA ML196DF045XE36B PERFORMANCE (Less Filter) External Air Volume / Watts at Various Blower Speeds Static High Medium-High Medium Medium-Low Pressure Watts Watts Watts Watts Watts in. w.g. 0.00 1455 1275 1175 0.10 1425 1250 1145 0.20 1395 1225 1115 0.30...
  • Page 5 PARTS ARRANGEMENT CONTROL BOX (Includes integrated control, transformer, circuit breaker and door switch) BLOWER MOTOR (hidden) BAG ASSEMBLY (shipping location) BLOWER ACCESS PANEL COMBUSTION AIR INDUCER BLOWER DECK DuralokPlus HEAT EXCHANGER ASSEMBLY BURNER ACCESS PANEL COLD END HEADER BOX COMBUSTION AIR INDUCER PRESSURE SWITCH PRIMARY LIMIT BURNER BOX ASSEMBLY...

  • Page 6: I-Unit Components

    I-UNIT COMPONENTS 3. Circuit Breaker (CB8) A 24V circuit breaker is also located in the control box. The switch provides overcurrent protection to the transformer ELECTROSTATIC DISCHARGE (ESD) (T1). The breaker is rated at 3A at 32V. If the current ex­ ceeds this limit the breaker will trip and all unit operation will Precautions and Procedures shutdown.
  • Page 7 TABLE 3 1/4” QUICK CONNECT TERMINALS 120HUM Humidifier 120VAC LINE 120VAC XFMR Transformer 120VAC CIRC Indoor blower 120VAC Indoor air quality accessory 120VAC NEUTRALS Common 120VAC HUM24 Humidifier 24VAC 3/16” QUICK CONNECT TERMINALS COOL Cooling tap 24VAC HEAT Heating tap 24VAC Continuous blower 24 VAC PARK (no power) Park terminal for unused speed taps...
  • Page 8 After a total of five trials for ignition (including the initial INTEGRATED CONTROL trial), the integrated control goes into Watchguard-Flame (Automatic Hot Surface Ignition System) Failure mode. After a 60-minute reset period, the inte­ grated control will begin the ignition sequence again. Fan Time Control Heating Fan On Time The fan on time of 30 seconds is not adjustable.
  • Page 9 ML196DFE Burner Box Assembly IGNITOR BURNERS ROLLOUT SWITCHES FRONT BURNER BOX PLATE SENSOR GAS VALVE FIGURE 5 B-Heating Components 2. Heat Exchanger (Figure 6) ML196DFE units use an aluminized steel primary and Combustion air inducer (B6), primary limit control (S10), stainless steel secondary heat exchanger assembly.
  • Page 10 5. Flame Sensor (Figure 5) Primary Limit Location and Heat Exchanger A flame sensor is located on the left side of the burner sup­ port. The sensor is mounted on the bottom burner box plate and the tip protrudes into the flame envelope of the left- most burner.
  • Page 11 Measuring Flame Signal Flame Signal In Microamps Normal Drop Out  1.5  0.4 0.5 - 1.4 Flame Sensor Terminal Remove Sensor Wire from Intergrated Control and Intergrated Connect Alligator Clip (−) Control to Frame Sensor Lead Remove Sensor Wire from Intergrated Control and Connect Alligator Clip (+) to Terminal on Control...
  • Page 12 Test 1 Check ignitor circuit for correct resistance. Remove 4-pin plug from control. Check ohms reading across terminals 2 and 4. Reading should be between 39 and 70 ohms. If value is correct, this is the only test needed. If the reading on the meter is not correct, (0 or infinity) then a second test is needed.
  • Page 13 7. Combustion Air Inducer (B6) Pressure Switch & Cold End Header Box All ML196DFE units use a combustion air inducer to move air through the burners and heat exchanger during 24VAC BRACKET heating operation. The blower uses a shaded pole TERMINALS 120VAC motor.
  • Page 14 Measuring Pressure Differential Black Tubing (positive +) Red and Black Tubing or Red Tubing (negative -) To Cold End Header Box To Cold End Header Box Field Provided Tubing To Pressure Switch “+” High “-” 1 - Remove thermostat demand and allow unit to cycle off.
  • Page 15 TABLE 7 Problem Corrective Action Check that the pressure switch is open without the combustion air inducer operat­ Pressure switch stuck closed ing. Replace if defective. Pressure switch does not close due to Check for restricted vent. Remove all blockage. obstruction in vent pipe.
  • Page 16 C- Blower Compartment BLOWER WHEEL REPLACEMENT IMPORTANT Center Blower Wheel in Blower Housing Each blower is statically and dynamically bal­ anced as an assembly before installation in the unit. ML196DFE units are equipped with a constant torque ECM motor. It has a DC motor coupled to an electronic control module both contained in the same motor housing.
  • Page 17 Multi−Meter (set to VAC) Multi−Meter (set to VAC) Test 1 Test 3 (if necessary) Turn on power to unit. Check for 120 volts across terminals Check for 120 volts across terminals “CIRC” and “Neutrals” “L” and “N” on input plug P48. If voltage is present continue on the integrated control.
  • Page 18 Replacing the Motor Module Motor Test 1. Disconnect electrical power to unit. 2. Remove unit access panel. 3. Unplug the two harnesses from the motor control mod­ ule. See figure 17. Unplug the Two Harness Connection TWO HARNESS FIGURE 19 CONNECTIONS TABLE 8 MOTOR...

  • Page 19: Placement And Installation

    II-PLACEMENT AND INSTALLATION IMPORTANT Pipe & Fittings Specifications ML196DFE exhaust and intake connections are All pipe, fittings, primer and solvent cement must conform made of PVC. Use PVC primer and solvent cement with American National Standard Institute and the Ameri­ when using PVC vent pipe.
  • Page 20 TABLE 10 OUTDOOR TERMINATION USAGE* STANDARD CONCENTRIC Flush­ Wall Kit Wall Ring Kit Mount 1-1/2 inch 2 inch 3 inch Vent 2 inch 3 inch 2 inch Pipe Input Size Field Dia. in. 51W11 71M80 69M29 Fabricated 44J40 (US) 22G44 (US) (US) (US) 60L46 (US)
  • Page 21 7 - Immediately after applying last coat of cement to pipe, REPLACING FURNACE THAT and while both inside socket surface and end of pipe WAS PART OF A COMMON are wet with cement, forcefully insert end of pipe into CHIMNEY VENT SYSTEM OR GAS socket until it bottoms out.
  • Page 22 Vent Piping Guidelines Piping Size Process ® NOTE - Lennox has approved the use of DuraVent Centrotherm manufactured vent pipe and terminations as What is the ® an option to PVC. When using the PolyPro by DuraVent or furnace capacity? ®...
  • Page 23 TABLE 12 Maximum Allowable Intake or Exhaust Vent Length 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. Standard Termination at Elevation 0 - 4500 ft 1-1/2”...
  • Page 24 TABLE 13 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. Standard Termination at Elevation 0 - 10,000 ft 1-1/2”...
  • Page 25 TYPICAL EXHAUST PIPE CONNECTIONS 045/070 Only 2” 1−1/2” 2” 2” 2” 2” TRANSITION 2” Exhaust Exhaust 3” DO NOT transition from larger to smaller pipe in horizontal runs TRANSITION of exhaust pipe. INTAKE DO NOT transition from smaller EXHAUST *2” to larger pipe size in horizontal TOP VIEW runs of exhaust pipe.
  • Page 26 Intake Piping TYPICAL AIR INTAKE PIPE CONNECTIONS The ML196DFE furnace may be installed in either direct NON−DIRECT VENT APPLICATIONS vent or non-direct vent applications. In non-direct vent applications, when intake air will be drawn into the furnace INTAKE SCREEN from the surrounding space, the indoor air quality must be (Provided) considered.
  • Page 27 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 figure 30 or 31. In addition, position termination so it is free from any obstructions and 12”...
  • Page 28 TABLE 14 Maximum Allowable Exhaust Vent Pipe Length Without Insulation In Unconditioned Space For Winter Design Temperatures Single - Stage High Efficiency Furnace Unit Input Size Winter Design Vent Pipe Temperatures °F (°C) Diameter 1-1/2 in. 32 to 21 2 in. (0 to -6) 2-1/2 in.
  • Page 29 Conditioned Space Exhaust Pipe Pipe Insulation Intake Conditioned Pipe Unconditioned Space Space FIGURE 29 Page 29...
  • Page 30 ‡ 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 31 ‡ 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 31 Page 31...
  • Page 32 Details of Intake and Exhaust Piping Terminations for 3”(76mm) MAX. Inches(mm) SIZE TERMINATION Direct Vent Installations PIPE PER TABLE 15. NOTE - In Direct Vent installations, combustion air is tak­ UNCONDITIONED en from outdoors and flue gases are discharged to out­ ATTIC SPACE 8”...
  • Page 33 7. If intake and exhaust piping must be run up a side wall to position above snow accumulation or other ob­ 12” structions, piping must be supported. At least one EXHAUST (305mm) VENT 5-1/2” bracket must be used within 6” from the top of the el­ 5”...
  • Page 34 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 35 Details of Exhaust Piping Terminations for Non‐Direct ML196DFE NON-DIRECT VENT APPLICATION Vent Applications USING EXISTING CHIMNEY Exhaust pipes may be routed either horizontally through an SIZE TERMINATION STRAIGHT-CUT OR outside wall or vertically through the roof. In attic or closet ANGLE-CUT IN DIRECTION PIPE PER TABLE 15.
  • Page 36 Heat cable kit is avail­ 1/2” drive socket extension and remove plug. Install able from Lennox in various lengths; 6 ft. (1.8m) - kit provided 3/4 NPT street elbow fitting into cold end no. 26K68 and 24 ft. (7.3m) - kit no. 26K69.
  • Page 37 Condensate Trap With Optional Overflow Switch IMPORTANT When combining the furnace and evaporator From Evaporator Coil coil drains together, the A/C condensate drain Field Provided Vent outlet must be vented to relieve pressure in or­ 1” min. 2” max. above condensate drain.
  • Page 38 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 39: Iii-Start-Up

    III-START‐UP 2 - Set the thermostat to the lowest setting. 3 - Turn off all electrical power to the unit. A-Preliminary and Seasonal Checks 4 - This furnace is equipped with an ignition device which 1 - Inspect electrical wiring, both field and factory installed for loose connections.

  • Page 40: Iv-Heating System Service Checks

    Use of a specialty Gas Leak Detector is strongly recommended. It is available A-C.S.A. Certification through Lennox under part number 31B2001. See Corp. All units are C.S.A. design certified without modifications. 8411-L10, for further details.
  • Page 41 Negative Barbed Fitting (remove for manifold adjustment) (−) 2” Long Square Tubing (remove for manifold adjustment) Manifold Pressure Outlet Gas Valve Regulator Vent Hose (to burner box) Barbed Fitting 10” Long Square Tubing Measuring Device FIGURE 52 TABLE 16 Manifold and Supply Line Pressure 0-10,000ft. Supply Line Manifold Pressure in.
  • Page 42 F- Proper Gas Flow (Approximate) G- Proper Combustion Furnace should operate at least 15 minutes with correct Gas Flow (Approximate) manifold pressure and gas flow rate before checking com­ TABLE 17 bustions. Take sample beyond the flue outlet and GAS METER CLOCKING CHART compare to table 18.
  • Page 43 I- Proper Ground and Voltage 2 - In addition, measure the AC voltage from Line Hot to Line Neutral (spade terminals) on the integrated con­ WARNING trol. See figure 53. This voltage should be in the range of 97 to 132 Vac Electric Shock Hazard.

  • Page 44: V-Typical Operating Conditions

    V-TYPICAL OPERATING CHARACTERISTICS C-External Static Pressure 1 - Tap locations shown in figure 55. A-Blower Operation and Adjustment1 2 - Punch a 1/4” diameter hole in supply and return air ple­ NOTE- The following is a generalized procedure and nums. Insert manometer hose flush with inside edge of hole or insulation.

  • Page 45: Vi-Maintenance

    Before using any filter with this system, check the specifications provided by the filter manufacturer against the data given in the appropriate Lennox Product Specifications bulletin. Additional informa­ FIGURE 57 tion is provided in Service and Application Note ACC­00­2 (August 2000).
  • Page 46 Condensate Hose Screen (Figure 58) 15 - Loosen clamps on exhaust and air intake pipe seal Check the condensate hose screen for blockage and clean plate. Slide exhaust and intake pipes up and out to if necessary. clear blower deck. Remove exhaust and air intake 1 - Turn off power to the unit.
  • Page 47 38 - Reinstall gas valve manifold assembly. Reconnect 5 - -Loosen clamps and remove combustion air intake gas supply line to gas valve. flexible connector (if equipped). 5 - Mark and disconnect sensor wire from the sensor. Dis­ 39 - Reinstall burner box cover if equipped. connect plug from the ignitor at the burner box.

  • Page 48: Vii-Wiring And Sequence Of Operation

    VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION Line voltage is applied to L1 and N. the T1 low voltage transformer is energized, and line voltage is applied to B3 indoor blower. S47 rollout switch(es) must be closed in order for 24V from transformer to be output on integrated control ”R” to power thermostat. When there is a call for heat, W1 of the thermostat energizes W of the furnace control with 24VAC.

  • Page 49: Viii-Troubleshooting

    VIII-Troubleshooting: Heating Sequence of Operation HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER DELAY OFF. CONTROL SELF-CHECK OKAY? LED SLOW FLASH (RESET CONTROL BY TURNING MAIN POWER OFF.) LED FLASHES CODE 1 - POLARITY IS POLARITY CORRECT? REVERSED.
  • Page 50 Troubleshooting: Heating Sequence of Operation (Continued) HEATING SEQUENCE CONTINUED NORMAL HEATING MODE ABNORMAL HEATING MODE 15‐SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. LED FLASHES CODE 13 - LOW LINE VOLTAGE. ONCE VOLTAGE IS ABOVE IGNITOR WARM‐UP -- 20 SECONDS. IS VOLTAGE ABOVE 70 VOLTS? 75 VOLTS, HEATING SEQUENCE RESTARTS.
  • Page 51 Troubleshooting: Cooling Sequence of Operation COOLING SEQUENCE OF OPERATION NORMAL COOLING MODE ABNORMAL COOLING MODE POWER ON IGNITION CONTROL MAIN POWER ON. LED FLASHES STEADY - CIRCUIT BOARD FAILURE CONTROL SELF DIAGNOSTIC CHECK. GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. IS CONTROL OPERATING NORMALLY? INDOOR BLOWER OFF WITH NORMAL DELAY.
  • Page 52 Troubleshooting: Continuous Fan / Accessories Sequence of Operation CONTINUOUS FAN / ACCESSORIES SEQUENCE OF OPERATION LED: SLOW FLASH RATE REMAINS UNCHANGED THROUGHOUT SEQUENCE. MANUAL FAN SELECTION MADE AT THERMOSTAT. CONTROL (G) ENERGIZES SYSTEM FAN AT FAN SPEED. EAC TERMINAL IS ENERGIZED. THERMOSTAT CALLS FOR HEAT (W).

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