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Lennox ML196UHE Series Unit Information
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Lennox ML196UHE Series Unit Information

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S e r v i c e L i t e r a t u r e
ML196UHE series units are high-efficiency gas furnaces
manufactured with Lennox DuralokPlus aluminized steel
clamshell-type heat exchangers, with a stainless steel
condensing coil. ML196UHE units are available in heating
input capacities of 30,000 to 135,000 Btuh and cooling
applications from 1.5 through 5 tons. Refer to Engineering
Handbook for proper sizing.
Units are factory equipped for use with natural gas. A kit
is available for conversion to LP/Propane operation. All
ML196UHE 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 out-
lined 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 disconnect
switch(es). Unit may have multiple power
supplies.

Table of Contents

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
. . . . . . . . . . . . . . . . . . . . . . . . . . 3
Blower Performance Data
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
II Placement and Installation . . . . . . . . . . . . . . . . . . . . 23
III-Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
V-Typical Operating Conditions
VI-Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
VII-Sequence of Operation and Flow Charts
UNIT INFORMATION
UNIT INFORMATION
ML196UHE SERIES UNITS
. . . . . . . . . . . . . . . . . . . . . . 4
. . . . . . . . . . . . . . 44
. . . . . . . . . . . . . . . . . 48
. . . . . . 52
Corp 1911-L7
Revised 08/2022
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
instale (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.
Page 1
ML196UHE
WARNING
CAUTION
©2016 Lennox Industries, Inc.

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Summary of Contents for Lennox ML196UHE Series

  • Page 1: Table Of Contents

    S e r v i c e L i t e r a t u r e Revised 08/2022 ML196UHE SERIES UNITS ML196UHE series units are high-efficiency gas furnaces manufactured with Lennox DuralokPlus aluminized steel clamshell-type heat exchangers, with a stainless steel condensing coil.

  • Page 2: Specifications

    SP ECIF ICATIONS ML196UH ML196UH ML196UH ML196UH ML196UH Model No. Heating 030XE36B 045XE36B 070XE36B 070XE48B 090XE36C Performance AFUE Input - Btuh 30,000 44,000 66,000 66,000 88,000 Output - Btuh 29,000 42,800 63,900 63,900 85,600 Temperature rise range - °F 25 - 55 35 - 65 35 - 65 30 - 60...

  • Page 3: Optional Accessories

    O P T IONA L AC C ESSORIES “B” Width “C” Width “D” Width Models Models Models CABINET ACCESSORIES Horizontal Suspension Kit - Horizontal only 51W10 51W10 51W10 Return Air Base - Upflow only 50W98 50W99 50W99 High Performance Economizer (Commercial Only) 10U53 10U53 10U53...
  • Page 4 BLO WER DATA ML196UH030XE36B 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 1435 1170 1000 0.10 1400 1130 0.20 1360...
  • Page 5 BLO WER DATA ML196UH090XE36C 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 1470 1355 1195 0.10 1445 1330 1170 0.20...
  • Page 6 BLO WER DATA ML196UH110XE60C PERFORMANCE (Less Filter) Air Volume / Watts at Different Blower Speeds Single Side Return Air − Air volumes in bold (over 1800 Bottom Return Air, Side Return Air with Return Air from cfm) require Optional Return Air Base and field fabricated External Both Sides or Return Air from Bottom and One Side.
  • Page 7 PARTS IDENTIFICATION FLEXIBLE NO-HUB EXHAUST COLLAR BURNER BOX ASSEMBLY TOP CAP GAS VALVE DuralokPlus HEAT EXCHANGER ASSEMBLY COMBUSTION AIR INDUCER BURNER ACCESS PANEL BAG ASSEMBLIES (shipping location) PRIMARY LIMIT COLD END BLOWER ACCESS HEADER BOX PANEL BLOWER COMBUSTION ASSEMBLY AIR PRESSURE SWITCH CONTROL BOX former, circuit breaker and interlock switch)

  • Page 8: I-Unit Components

    I-UNIT COMPONENTS 3. Circuit Breaker (CB8) A 24V circuit breaker is also located in the control box. The ELECTROSTATIC DISCHARGE (ESD) switch provides overcurrent protection to the transform- Precautions and Procedures er (T1). The breaker is rated at 3A at 32V. If the current CAUTION exceeds this limit the breaker will trip and all unit opera- tion will shutdown.
  • Page 9 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 Park terminal for speed taps...
  • Page 10 Fan Time Control - Ignition Control 103217-03 IGNITION CONTROL 103217-03 Heating Fan On Time The fan on time of 30 seconds is not adjustable. Heating Fan Off Time Fan off time (time that the blower operates after the heat demand has been satisfied) can be adjusted by moving the jumper to a different setting.
  • Page 11 TABLE 5 Ignition Control 107163-01 RED LED Flash Code Diagnostic Codes / Status of Furnace No Power to Control or Board Fault Detected Board Fault Detected Fast Heartbeat Call for Heat / Burner Operation Slow Heartbeat Normal Operation – Idle, Continuous Fan, or Cool 1 Flash Reverse Line Voltage Polarity or Phasing of 120V power 2 Flashes...
  • Page 12 Burner Box Assembly Burner Assembly Rollout Switch(s) Flame Sensor Ignitor Gas Valve Burner Box Front FIGURE 6 B-Heating Components The combustion air inducer pulls fresh air through the burner box. This air is mixed with gas in the burners. The Combustion air inducer (B6), primary limit control (S10), gas / air mixture is then burned at the entrance of each ignitor, burners, flame rollout switch (S47), gas valve...
  • Page 13 5. Flame Sensor (FIGURE 6) Primary Limit Location and Heat Exchanger A flame sensor is located on the left side of the burner support. The sensor is mounted on the front burner box plate and the tip protrudes into the flame envelope of the leftmost burner.
  • Page 14 Measuring Flame Signal Flame Signal In Microamps Normal Drop Out 0.5 - 1.4 Flame Sensor Wire Remove sensor from integrated control and connect alligator clip (−) to flame sensor lead. Multi−Meter Intergrated Control Set Dial to DC MicroAmps Flame Sensor Terminal (−) T o Flame Terminal...
  • Page 15 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 16 8. Combustion Air Pressure Switch (FIGURE 11) lems in the intake or exhaust piping, but may indicate ML196UHE series units are equipped with a differential problems in the heat exchanger, condensing coil, header pressure switch located on the cold end header box. The boxes, combustion inducer or other components.
  • Page 17 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 18 TABLE 8 Problem Corrective Action Check that the pressure switch is open without the com- Pressure switch stuck closed bustion air inducer operating. Replace if defective. Pressure switch does not close due to obstruction in vent Check for restricted vent. Remove all blockage. Check for pipe.
  • Page 19 C- Blower Compartment BLOWER WHEEL REPLACEMENT IMPORTANT Center Blower Wheel in Blower Housing Each blower is statically and dynamically balanced as an assembly before installation in the unit. ML196UHE 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 20 Multi−Meter (set to VAC) Multi−Meter (set to VAC) Test 1 Test 3 (if necesssary) 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 21 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 module. See FIGURE 17. 4 - Remove the two hex head bolts securing the motor control module to the motor.

  • Page 22: Placement And Installation

    II-PLACEMENT AND INSTALLATION IMPORTANT Pipe & Fittings Specifications Exhaust and intake connections are made of PVC. All pipe, fittings, primer and solvent cement must conform Use PVC primer and solvent cement when using with American National Standard Institute and the Ameri- PVC vent pipe.
  • Page 23 TABLE 11 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 24 NOTE - Assembly should be completed within 20 REPLACING FURNACE THAT WAS PART OF A seconds after last application of cement. Hammer COMMON VENT SYSTEM blows should not be used when inserting pipe. 8 - After assembly, wipe excess cement from pipe at CHIMNEY OR GAS end of fitting socket.
  • Page 25 TABLE 12 Vent Piping Guidelines MINIMUM VENT PIPE LENGTHS NOTE - Lennox has approved the use of DuraVent ® Centrotherm manufactured vent pipe and terminations ML196UHE Model MIN. VENT LENGTH* as an option to PVC. When using the PolyPro by Du- ®...
  • Page 26 TABLE 13 Maximum Allowable Intake or Exhaust Vent Length in Feet 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 27 TABLE 13 Continued Maximum Allowable Intake or Exhaust Vent Length in Feet 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 28 TABLE 14 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 29 TYPICAL EXHAUST AND INTAKE PIPE CONNECTIONS IN UPFLOW DIRECT OR NON-DIRECT VENT APPLICATIONS 2” EXHAUST EXHAUST INTAKE INTAKE 2” 2” 2” 2” 2” 3” 3” 030/045/070 Only 1−1/2” TRANSITION Exhaust 2” 6” Min Exhaust DO NOT transition from larger to smaller DO NOT transition pipe in horizontal runs from smaller to larger...
  • Page 30 Intake Piping (FIGURE 25 and FIGURE 26) TYPICAL AIR INTAKE PIPE CONNECTIONS UPFLOW NON−DIRECT The ML196UHE furnace may be installed in either direct VENT APPLICATIONS vent or non-direct vent applications. In non-direct vent ap- plications, when intake air will be drawn into the furnace INTAKE DEBRIS from the surrounding space, the indoor air quality must be...
  • Page 31 General Guidelines for Vent Terminations CAUTION In Non-Direct Vent applications, combustion air is taken If this unit is being installed in an application with from indoors and the flue gases are discharged to the out- combustion air coming in from a space serviced by doors.
  • Page 32 TABLE 15 Maximum Allowable Exhaust Vent Pipe Length (in ft.) Without Insulation In Unconditioned Space For Winter Design Temperatures Single - Stage High Efficiency Furnace Winter Vent Unit Input Size Design Pipe Temp °F (°C) Diam 1-1/2 in 32 to 21 2 in (0 to -6) 2-1/2 in...
  • Page 33 ‡ 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 34 ‡ 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 33 Page 34...
  • Page 35 Details of Intake and Exhaust Piping Terminations for 3”(76mm) MAX. Inches(mm) Direct Vent Installations NOTE - In Direct Vent installations, combustion air is taken UNCONDITIONED ATTIC SPACE from outdoors and flue gases are discharged to outdoors. 8” (203mm) MIN NOTE - Flue gas may be slightly acidic and may adverse- 12”...
  • Page 36 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 Accelerator not required REDUCER MAY BE for 3” concentric one bracket must be used within 6” from the top of REQUIRED TO ADAPT DIFFERENT VENT PIPE the elbow and then every 24”...
  • Page 37 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 38 FIGURE 43 KIT 15Z70 Crawl Space and Extended Horizontal Venting (CANADA) Lennox provides kit 51W18 (USA) kit 15Z70 (Canada) to FIGURE 45 install 2” or 3” PVC exhaust piping through the floor joists Condensate Piping and into the the crawl space. See FIGURE 45. This kit can...
  • Page 39 NOTE - If necessary the condensate trap may be installed CONDENSATE TRAP LOCATIONS up to 5’ away from the furnace. Use PVC pipe to connect (Unit shown in upflow position with remote trap) trap to furnace condensate outlet. Piping from furnace must slope down a minimum of 1/4”...
  • Page 40 If this is not possible, a heat cable kit may be used on the condensate trap and line. Heating cable kit is available from Lennox in various lengths; 6 ft. (1.8m) - kit no. 26K68 and 24 ft. (7.3m) - kit no. 26K69.
  • Page 41 Furnace with Evaporator Coil Using a Separate Drain (Unit shown in horizontal left-hand discharge position) Field Provided Vent Evaporator (4” min. to 5” max. above Coil condensate connection) 4”min 5”max 5’ max. PVC Pipe Only Condensate Drain Connection (Trap at coil is optional) Drain Pan Piping from furnace and evaporator coil must slope down a minimum 1/4”...
  • Page 42 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 43: Iii-Start-Up

    III-START-UP Gas Valve Operation (FIGURE 55) 1 - STOP! Read the safety information at the beginning A-Preliminary and Seasonal Checks of this section. 1 - Inspect electrical wiring, both field and factory 2 - Set the thermostat to the lowest setting. installed for loose connections.

  • Page 44: Iv-Heating System Service Checks

    Use of a specialty Gas Leak Detector is strongly recom- 5 - Shut unit off and remove manometer as soon as mended. It is available through Lennox under part number an accurate reading has been obtained. Take care 31B2001. See Corp. 8411-L10, for further details.
  • Page 45 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 57 G- Proper Combustion H- High Altitude Furnace should operate at least 15 minutes with correct NOTE - In Canada, certification for installations at eleva-...
  • Page 46 TABLE 19 Manifold and Supply Line Pressure 0-10,000ft. Manifold Pressure in. wg. Supply Line Pressure ML196 in. w.g. Unit 0 - 4500 ft 4501 - 5500 ft 5501 - 6500 ft 6501 - 7500 ft 7501 - 10,000 ft 0 - 10000 ft. Natural 13.0 Models...
  • Page 47 I- Proper Ground and Voltage 2 - In addition, measure the AC voltage from Line Hot to Line Neutral (spade terminals) on the integrated WARNING control. See FIGURE 58. This voltage should be in the range of 97 to 132 Vac. Electric Shock Hazard.
  • Page 48 V-TYPICAL OPERATING CHARACTERISTICS C-External Static Pressure 1 - Tap locations shown in FIGURE 60. A-Blower Operation and Adjustment1 2 - Punch a 1/4” diameter hole in supply and return NOTE- The following is a generalized procedure and does air plenums. Insert manometer hose flush with not apply to all thermostat controls.

  • Page 49: Vi-Maintenance

    True RMS Meter 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 information is provided in Service and Application Note ACC002 FIGURE 61 (August 2000).
  • Page 50 Winterizing and Condensate Trap Care 12 - Mark and disconnect all combustion air pressure tubing from cold end header collector box. 1 - Turn off power to the furnace. 13 - Mark and remove wires from pressure switch 2 - Have a shallow pan ready to empty condensate assembly.
  • Page 51 35 - Use securing screws to reinstall flue collar to the top Cleaning the Burner Assembly (if needed) cap on the furnace. Reconnect exhaust piping and 1 - Turn off electrical and gas power supplies to furnace. exhaust drain tubing. Remove upper and lower furnace access panels.
  • Page 52 VII-WIRING DIAGRAM AND SEQUENCE OF OPERATION 1 - Line voltage is applied to L1 and N. the T1 low voltage transformer is energized, and line voltage is applied to B3 indoor blower. 2 - S47 rollout switch(es) must be closed in order for 24V from transformer to be output on integrated control ”R” to power thermostat. 3 - When there is a call for heat, W1 of the thermostat energizes W of the furnace control with 24VAC.
  • Page 53 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 REVERSED.
  • Page 54 Heating Sequence of Operation Continued HEATING SEQUENCE CONTINUED 15 SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. LED FLASHES CODE 13 - LOW LINE VOLTAGE. ONCE VOLTAGE IS ABOVE IS VOLTAGE ABOVE 70 VOLTS? IGNITOR WARM UP -- 20 SECONDS. 75 VOLTS, HEATING SEQUENCE RESTARTS.
  • Page 55 Cooling Sequence of Operation COOLING SEQUENCE OF OPERATION POWER ON IGNITION CONTROL MAIN POWER ON. GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF WITH NORMAL DELAY. CONTROL SELF DIAGNOSTIC CHECK. SIGNAL CIRCUIT BOARD FAILURE AT LED. IS CONTROL OPERATING NORMALLY? INTERRUPT MAIN POWER TO RESET CONTROL.
  • Page 56 Continuous Fan / Accessories Sequence of Operation CONTINUOUS FAN 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). SYSTEM FAN CONTINUES FAN SPEED WITHOUT THERMOSTAT CALLS FOR COOLING.
  • Page 57 Page 57...

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