Lennox SLP99UHV Series Unit Information
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Lennox SLP99UHV Series Unit Information

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Table of Contents

S e r v i c e L i t e r a t u r e
SLP99UHV series units are high-efficiency upflow, hori-
zontal right and left) gas furnaces equipped with variable
capacity gas valve, variable speed combustion air inducer
and variable speed indoor blower motor. All models are
designed only for direct vent (dual pipe) venting system.
SLP99UHV units are available in heating capacities from
66,000 to 132,000 Btuh (19.3 to 38.6 kW) and cooling ap-
plications from 2 to 5 tons (7.0 kW to 17.5 kW). Refer to
Engineering Handbook for proper sizing.
Units are factory-equipped for use with natural gas. Kits
are available for conversion to LPG operation. SLP99UHV
models include a SureLight
control that can be used with a Lennox communicating
thermostat as part of a communicating comfort system.
All SLP99UHV units meet the California Nitrogen Oxides
(NOx) Standards and California Seasonal Efficiency re-
quirements.
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as rec-
ommendations only and do not supersede or replace local
or state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommendations only and do not con-
stitute code.

TABLE OF CONTENTS

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . Page 3
Blower Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . Page 20
II Communicating Thermostat . . . . . . . . . . . . . . Page 44
IV Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 63
V Heating System Service Checks . . . . . . . . . . Page 60
VII Maintenanc . . . . . . . . . . . . . . . . . . . . . . . . . . Page 71
VIII Wiring and Sequence of Operation
XI Field Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . Page 82
UNIT INFORMATION
UNIT INFORMATION
SLP99UHV SERIES UNITS
variable capacity integrated
®
. . . . . Page 74
100001
10/2021
Improper
installation,
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.
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.
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
SLP99UHV
WARNING
adjustment,
WARNING
CAUTION
©2016 Lennox Industries, Inc.
alteration,

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Summary of Contents for Lennox SLP99UHV Series

  • Page 1: Table Of Contents

    SureLight variable capacity integrated ® control that can be used with a Lennox communicating thermostat as part of a communicating comfort system. All SLP99UHV units meet the California Nitrogen Oxides (NOx) Standards and California Seasonal Efficiency re- quirements.

  • Page 2: Specifications

    SP ECIF ICATIONS Model No. SLP99UH070XV36B SLP99UH090XV36C SLP99UH090XV48C Heating AFUE 98.1% 98.1% 98.2% Performance Maximum Input - Btuh 66,000 88,000 88,000 Output - Btuh 64,000 85,000 85,000 Temperature rise range - °F 50 - 80 60 - 90 50 - 80 Gas Manifold Pressure (in.

  • Page 3: Optional Accessories

    OPT IONAL AC C ESSORIES - ORD ER SEPARAT ELY NOTE - FURNACES CANNOT BE TWINNED! “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 51W00...

  • Page 4: Blower Data

    First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm. ®...
  • Page 5 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm. ®...
  • Page 6 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm. ®...
  • Page 7 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm. ®...
  • Page 8 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm. ®...
  • Page 9 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 250 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 250 cfm. ®...
  • Page 10 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 380 cfm. ®...
  • Page 11 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 3808 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 380 cfm. ®...
  • Page 12 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 380 cfm. ®...
  • Page 13 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm. ®...
  • Page 14 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm. ®...
  • Page 15 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm. ®...
  • Page 16 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm. ®...
  • Page 17 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm. ®...
  • Page 18 First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position. Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position. minimum 380 cfm. Lennox iHarmony Zoning System Applications - Minimum blower speed is 450 cfm. ®...
  • Page 19 BURNER BOX ASSEMBLY PRESSURE SWITCHES HEAT EXCHANGER VARIABLE CAPACITY PRIMARY LIMIT GAS VALVE VARIABLE SPEED COMBUSTION AIR INDUCER BAG ASSEMBLIES (shipping location) COLD END HEADER ACCESS PANEL VARIABLE SPEED BLOWER MOTOR SHIPPING BLOCK SIGHT GLASS (-135 UNITS ONLY) INNER BLOWER ACCESS PANEL CONTROL BOX (includes variable capacity integrated control...

  • Page 20: I Unit Components

    Transformers on all models are rated 40VA with a 120V primary and a 24V 4. Integrated Control (A92) secondary. SLP99UHV units are equipped with the Lennox SureLight 2. Interlock Switch (S51) ® variable-capacity integrated control. This control can be...
  • Page 21 Electronic Ignition Three-Stage Timed Operation At the beginning of the heat cycle the SureLight integrat- Using a single-stage thermostat the system will operate ® ed control monitors the low fire combustion air inducer in a three stage timed mode. Upon a call for heat and a pressure switch.
  • Page 22 NEUTRAL COMBUSTION TERMINALS AIR INDUCER CONNECTOR IGNITOR CONNECTOR FLAME SENSE DIAGNOSTIC LINE VOLTAGE PUSH BUTTON TERMINALS DIP SWITCHES ON-BOARD LINKS OUTDOOR AIR INDOOR SENSOR BLOWER TERMINALS 7-SEGMENT CONNECTOR DIAGNOSTIC LED W915 Y1 TO Y2 DISCHARGE AIR SENSOR W951 R TO O TERMINALS W914 R TO DS FACTORY TEST...
  • Page 23 SLP99UHV INTEGRATED CONTROL CONFIGURATION GUIDE FIGURE 5 Page 23...
  • Page 24 TABLE 3 Thermostat Selection Switch Settings Operation Thermostat Switch 1 Switch 2 Switch 3 Variable Capacity Heat (35% to 100%) Two-Stage 2nd stage delay OFF = 7 minutes Three-Stage Heat Single-Stage ON = 12 minutes 3rd stage delay (35%, 70%, 100%) 10 minutes fixed Two-Stage Heat (W1 70%, W2 100%) Two-Stage...
  • Page 25 Switches 10 and 11 -- Cooling Mode Blower Speed Ad- Ramping Option A (Factory Selection) justment -- Switches 10 and 11 are used to select blower • Motor runs at 50% for 30 seconds. speed adjustment settings. The unit is shipped from the •...
  • Page 26 TABLE 9 TABLE 10 Low Heat Blower Speeds High Heat Blower Speeds Thermostat Thermostat Blower DIP Switch Settings DIP Switch Settings Blower Speed Demand Demand Speed Adjustments Adjustments + 15% + 15% High Heat + 7.5% + 7.5% Low Heat (R to W1 &...
  • Page 27 On-Board Link W914 DS to R (FIGURE 4) While in the Field Test mode the technician can: • Initiate furnace ignition and move to and hold low- On-board link W914, is a clippable connection between fire rate by applying a R to W1 jumper. terminals DS and R on the integrated control.
  • Page 28 TABLE 11 Idle Menu Options These options are displayed on the menu when the button is pressed during normal operation DISPLAY ACTION (when button released) No change (idle) remain in idle mode Solid “E” enter diagnostic mode Solid “-” enter field test mode NOTE - No change implies the display will continue to show whatever is currently being displayed for normal operation TABLE 12 Idle Menu Options...
  • Page 29 Configuring Unit Size Codes Power-Up - Number displayed represents by integrated control unit size code (furnace model − − and capacity). If three horizontal bars are displayed followed by continuous E203, furnace − control does not recognize unit size code. Configure per the following: Furnace control in IDLE mode No heating, cooling or indoor fan operation)
  • Page 30 TABLE 14 LED 7 Segment Status / Error Code Press the diagnostic push button and hold it to cycle through a menu of options. Every five seconds a new menu item will be displayed. Release the button when the desired mode is displayed. When a solid ”P”...
  • Page 31 Integrated Control Diagnostic Codes (Continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E200 Hard lockout - Rollout circuit open or previously Correct unit cause of rollout trip or replace flame rollout switch and test furnace open. operation.
  • Page 32 Integrated Control Diagnostic Codes (Continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E274 Soft lockout - Exceeded maximum number of See E 250. recycles. Last recycle failed due to the limit circuit opening or limit remained open longer than 3 minutes.
  • Page 33 Integrated Control Diagnostic Codes (Continued) Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover E402 LSOM - Outdoor unit system pressure trip. Compressor ran over 18 hours in air conditioning mode. LSOM - Compressor short-cycling (Running less than Outdoor unit pressure trip.
  • Page 34 TABLE 16 OPERATING SEQUENCE SLP99UHV and Single-Stage Outdoor Unit OPERATING SYSTEM DEMAND SYSTEM RESPONSE SEQUENCE Demand Relative Humidity Blower System Comments Step Compressor Condition Status (COOL) stage stage NO CALL FOR DEHUMIDIFICATION Normal Operation - Acceptable Compressor and indoor blower follow thermostat Normal Operation - demand Acceptable...
  • Page 35 BLOWER MOTOR COMPONENTS STATOR (WINDINGS) BEARING ROTOR FIGURE 8 A solid-state controller is permanently attached to the mo- tor. The controller is primarily an A.C. to D.C. converter. Power Choke Blower Motor Converted D.C. power is used to drive the motor. The con- (4 and 5 Ton Only) (B3) troller contains a microprocessor which monitors varying...
  • Page 36 Motor Start-Up Note: Do not apply 24V to pins 2 and 4 on P49. Doing so will cause permanent damage to the motor. When B3 begins start-up, the motor gently vibrates back 6 - Motor should run at 75%. and forth for a moment. This is normal. During this time 7 - Test is complete.
  • Page 37 TABLE 17 BLOWER B3 HARNESS CONNECTORS Ohm Meter Range P48 5 Pin Scale Measurement Range P49 4 Pin SHAFT In Words ohms two megohm - two 0 - 2,000,000 million ohms 200k two hundred kilohm 0 - 200,000 MOTOR with INTEGRATED - two hundred CONTROLLER thousand ohms...
  • Page 38 TEST B TABLE 18 Use an ohmmeter to measure the motor phase-to-phase Flame Signal in Microamps resistance by checking these combinations of the the 3-pin Normal Drop Out motor plug. For the purpose of this test, start at either end of the connector as lead 1.
  • Page 39 Burner Box Assembly burner assembly intake air collar rollout switch flame sensor Cover plate (-090XV60C model only) ignitor burner box front cover (remove screw to open cover) sight glass FIGURE 14 Page 39...
  • Page 40 Inlet and outlet pressure taps are located on the valve. P99UHV units located in the heating vestibule panel. LPG change over kits are available from Lennox. Kits in- When excess heat is sensed in the heat exchanger, the clude burner orifices and an LP gas valve.
  • Page 41 8. Combustion Air Inducer (B6) & Pressure Switch Combustion Air Inducer Troubleshooting (S18) • Is the CAI mounted correctly? All SLP99UHV units are equipped with a combustion air • Any air or condensate leaks? inducer (B6) and dual pressure switch assembly (high fire and low fire).
  • Page 42 Checks of pressure differential can aid in troubleshooting. 4 - Decrease RPM by 50, wait 5 seconds and look for Lennox provides a kit (10L34) if necessary. When measur- the low pressure switch to open. Repeat this step ing the pressure differential, readings should be taken at until it is open.
  • Page 43 Measuring Pressure Differential BLACK TUBING POSITIVE To Cold End Header Box Field Installed RED and BLACK TUBING or RED TUBING NEGATIVE Measuring Device Operate unit and observe measuring device reading. Remove thermostat demand and allow unit to cycle off. Readings will change as heat exchanger warms. Install a tee in the negative (-) line (red and black tubing or red a.

  • Page 44: Communicating Thermostat

    II-Communicating Thermostat (if applicable) In communicating applications a communicating thermostatmust be used. In these applications the thermostat overrides the DIP switch settings on the integrated control. Refer to the illustrations provided with the thermostat for installation, set- up and operation. See FIGURE 19 and FIGURE 20 for thermostat wiring in communicating applications. Communicating Enabled Furnace and Communicating Enabled Furnace and Non-Communicating Outdoor Unit...
  • Page 45 THERMOSTAT NOTE: 24V UV LIGHT APPLICATIONS plications. An additional transformer for UV light applications is required. COMMUNICATING LENNOX COMMUNICATING FURNACE HEPA BYPASS FILTER ENABLED FURNACE EL296V, SL280V, SL280VN, SL297V, SLP99V X2680 HEPA cutting DS to R will not cause INTERLOCK KIT...

  • Page 46: Placement And Installation

    III-PLACEMENT AND INSTALLATION CAUTION All pipe, fittings, primer and solvent cement must conform Solvent cements for plastic pipe are flammable liquids with American National Standard Institute and the Ameri- and should be kept away from all sources of ignition. can Society for Testing and Materials (ANSI/ASTM) stan- Do not use excessive amounts of solvent cement when dards.
  • Page 47 TABLE 22 OUTDOOR TERMINATION USAGE* STANDARD CONCENTRIC Wall Kit 1-1.2 inch 2 inch 3 inch Flush Mount Vent Pipe 2 inch 3 inch Input Size Field 71M80 (US) 69M29 (US) 60L46 (US) Dia. in. 51W11 (US) Fabricated 44W92 44W92 44W93 22G44 (US) 44J40 (US) 51W12...
  • Page 48 VENT (Check sizing for water heater only) Vent Piping Guidelines NOTE - Lennox has approved the use of DuraVent® and Centrotherm manufactured vent pipe and terminations as WATER HEATER FURNACE an option to PVC. When using the PolyPro by DuraVent ®...
  • Page 49 1 - Remove the caution sticker from flue coupling . used. Contact Lennox’ Application Department for assis- 2 - Fully insert flue coupling with both bands loosely tance in sizing vent pipe in these applications.
  • Page 50 TABLE 24 Maximum Allowable Intake or Exhaust Vent Length in Feet ust be same pipe size. *Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust m 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 - 7500’...
  • Page 51 TABLE 24 Continued Maximum Allowable Intake or Exhaust Vent Length in Feet ust be same pipe size. *Size intake and exhaust pipe length separately. Values in table are for Intake OR Exhaust, not combined total. Both Intake and Exhaust m 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 0 - 7501”...
  • Page 52 TYPICAL EXHAUST AND INTAKE PIPE CONNECTIONS IN UPFLOW 2” EXHAUST EXHAUST INTAKE INTAKE 2” 2” 2” 2” 2” 3” 3” 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 Exhaust of exhaust pipe.
  • Page 53 ‡ 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 28 Page 53...
  • Page 54 General Guidelines for Vent Terminations NOTE - See TABLE 25 for maximum allowed exhaust pipe length without insulation in unconditioned space during In Direct Vent applications, combustion air is taken from winter design temperatures below 32°F (0°C). If required outdoors and the flue gases are discharged to the out- exhaust pipe should be insulated with 1/2”...
  • Page 55 Conditioned Space Exhaust Pipe Pipe Insulation Intake Conditioned Pipe Unconditioned Space Space FIGURE 29 Details of Intake and Exhaust Piping Terminations for 3 - On roof terminations, the intake piping should Direct Vent Installations terminate straight down using two 90° elbows (See FIGURE 30).
  • Page 56 3”(76mm) MAX. Exiting Exhaust and Intake Vent Inches(mm) (different pressure zone) UNCONDITIONED ATTIC SPACE Roof T erminated 8” (203mm) MIN Exhaust Pipe 12” (305mm) ABOVE AVERAGE SNOW ACCUMULATION Inlet Air (Minimum 12 in. Furnace 305 MM) above 3” (76mm) OR grade or snow 2”...
  • Page 57 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 58 2” EXTENSION FOR 2” PVC Accelerator not required for PIPE1” EXTENSION FOR 3” 3” concentric PVC PIPE FURNACE EXHAUST FLASHING 12” (305mm) PIPE (Not Furnished) INTAKE Minimum Above Average Snow FURNACE Accumulation INTAKE PIPE GLUE EXHAUST END FLUSH INTO SHEET METAL STRAP TERMINATION (Clamp and sheet metal strap must be field installed to support...
  • Page 59 6 - If unit will be started immediately upon completion trap and line. Heating cable kit is available from Lennox of installation, prime trap per procedure outlined in in various lengths; 6 ft. (1.8m) - kit no. 26K68 and 24 ft.
  • Page 60 CONDENSATE TRAP LOCATIONS Furnace With Evaporator (Unit shown in upflow position with remote trap) Coil Using A Separate Drain FieldProvidedVent Evaporator drain Min. 1” Above Condensate line required Drain Connection (Trap at coil is optional) 1” Min. 2” Max. Field Provided Vent (1”...
  • Page 61 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 62 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 63: Start Up

    IV-START-UP BEFORE PLACING THE UNIT INTO OPERATION, the unit, smell all around the furnace area for gas. Be sure to A-Preliminary and Seasonal Checks smell next to the floor because some gas is heavier than air and will settle on the floor. 1 - Inspect electrical wiring, both field and factory installed for loose connections.

  • Page 64: Heating System Service Checks

    Use of a specialty Gas Leak Detector is strongly recommended. It Turn off unit power. Close manual and main gas valves. is available through Lennox under part number 31B2001. D-Extended Period Shutdown See Corp. 8411-L10, for further details.
  • Page 65 Use pressure test 4 - After allowing unit to stabilize for 5 minutes, record adapter kit (available as Lennox part 10L34) to assist in operating pressure signal and compare to value measurement.
  • Page 66 MANIFOLD PRESSURE MEASUREMENT Gas Valve Field Installed FIGURE 50 Negative Port Operating Signal (Delta P) Measurement Positive Port Red and Black Tubing - Black Tubing + Gas Valve Field Installed Measuring Device FIGURE 51 Page 66...
  • Page 67 H- Proper Combustion I- High Altitude NOTE - In Canada, certification for installations at eleva- Furnace should operate minimum 15 minutes with correct tions over 4500 feet (1372 m) is the jurisdiction of local manifold pressure and gas flow rate before checking co authorities.
  • Page 68 J- Proper Ground and Voltage 2 - In addition, measure the AC voltage from Line Hot to Line Neutral (spade terminals) on the integrated A poorly grounded furnace can contribute to premature control. See FIGURE 52. This voltage should be in ignitor failure.

  • Page 69: Typical Operating Characteristics

    VI-TYPICAL OPERATING CHARACTERISTICS Two types sensor are used (FIGURE 54 or FIGURE 55). If the sensor is suspect, check the location using FIGURE A-Blower Operation and Adjustment 54, FIGURE 56, FIGURE 57 and FIGURE 58 with tables TABLE 34, TABLE 36 and TABLE 38. Or check the lo- 1 - Blower operation is dependent on thermostat control cation using FIGURE 55, FIGURE 56, FIGURE 57 and system.
  • Page 70 Discharge Air Temperature Sensor Location TABLE 34 Sensor Type 1 Upflow Unit “a” “b” 070V36B 6” center Coil Plenum 090V36C 12” center 090V48C 1” 2” from left 090V60C 3” 2-1/2” from left Horizontal Right 110V60C 3” 2” from left 135V60D 1”...
  • Page 71 4 - Reinstall screens, reconnect hoses and turn on Before using any filter with this system, check the power to unit. 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 (August 2000).
  • Page 72 16 - Mark and disconnect any remaining wiring to Condensate Hose Screens heating compartment components. Disengage strain relief bushing and pull wiring and bushing through the hole in the blower deck. 17 - Remove the primary limit from the vestibule panel. 18 - Remove two screws from the front cabinet flange Hose Hose...
  • Page 73 39 - Reinstall gas valve manifold assembly. Reconnect 6 - Remove four screws which secure burner box gas supply line to gas valve. assembly to vest panel. Remove burner box from the unit. 40 - Reinstall burner box cover. 7 - Use the soft brush attachment on a vacuum cleaner 41 - Reconnect 2-pin plug to gas valve.
  • Page 74 FIGURE 62 NOTE - The thermostat selection DIP switch on the con- 3 - After the pre-purge is complete, a 20-second initial trol is factory-set in the “TWO-STAGE” position. ignitor warm-up period begins. The combustion air inducer continues to operate at the ignition speed. Applications Using a Two-Stage Thermostat 4 - After the 20-second warm-up period has ended, A - Heating Sequence -- Control Thermostat Selection...
  • Page 75 5 - If second-stage heat is required, the thermostat 6 - If the heating demand continues beyond the thirdstage on delay, the integrated control energizes second- stage heat contacts close and send a signal the inducer at high speed. The indoor blower motor to the integrated control.
  • Page 76 A - Sequence of Operation and Troubleshooting Flow Chart IGNITION AND CALL FOR LOW FIRE WITH TWO-STAGE THERMOSTAT Safety Check Verify There Is No Main Burner Flame After Indoor blower OFF Heat OFF Delay (Low Heat Speed) Limit Combustion Air Limit Indoor Blower De-Energize...
  • Page 77 CALL FOR HIGH FIRE WITH TWO-STAGE THERMOSTAT 2 Stage Thermostat 1st Call for High Fire? 2nd Stage Recognition Delay (30 Seconds) Combustion Air Inducer ON (100% Rate Speed) High Pressure Switch Increase Combustion Error Code Wait 5 Closes Within Air Inducer Speed Flashes Minutes 10 Seconds?
  • Page 78 CALL FOR HEAT SATISFIED RUN MODE (2 STAGE THEREMOSTAT) RUN MODE (SINGLE STAGE THERMOSTAT) 1ST OR 2ND STAGE CALL FOR HEAT ALL ALL INPUTS MONITORED (LIMIT, PRESSURE, INPUTS MONITORED (LIMIT, PRESSURE, CALL FOR HEAT / COOL, FLAME LEVEL) CALL FOR HEAT / COOL, FLAME LEVEL) 2nd Stage Heat 2nd Stage Call for Heat...
  • Page 79 IGNITION AND CALL FOR HEAT WITH SINGLE-STAGE THERMOSTAT Safety Check Verify There Is No Main Burner Flame Indoor Blower OFF After Heat OFF Delay (Low Heat Speed) Indoor Blower Limit Limit De-Energize Combustion Air Error Code Switch Closes Within 3 Gas Valve Flashes Inducer ON...
  • Page 80 CALL FOR COOLING 1st Stage Cooling Request Received Energize 1st Stage Cooling Contactor (Compressor & Fan) Indoor Blower On After 2-second delay Energize Indoor Blower (Per Ramping Profile) 1st Stage 2nd Stage Cooling Request Cooling Still Active? Request? Energize 2nd Stage Energize Indoor Blower Cooling Contactor (High Cooling mode)
  • Page 81 CONTINUOUS LOW SPEED INDOOR BLOWER SEQUENCE OF OPERATION Call for Continuous Blower Indoor Blower On (Speed Determined by Dip Switch settings) Request Maintain Indoor for Cooling Go to Call for Cooling Blower at set speed Received? Go to Call for Heat -- Two-Stage Thermostat Request Maintain Indoor for Heat...
  • Page 82 IX- Field Wiring For Non-Communicating Thermostats DIP Switch Settings and On-Board Links W914 W915 (DS to R) W951 (Y1 to Y2) Thermostat Wiring Connections DIP Switch 1 (O to R) Two-Stage cation or Heat Pumps Cooling Harmony 1Heat / 1 Cool Intact Intact Intact...

  • Page 83: Field Wiring

    Field Wiring Continued DIP Switch Settings and On-Board Links W914 W915 (DS to R) (Y1 to Y2) W951 Thermostat Wiring Connections Two-Stage DIP Switch 1 (O to R) cation or Cooling Heat Pumps Harmony 2 Heat / 2 Cool Intact Intact CONTROL OUTDOOR...
  • Page 84 Field Wiring Continued DIP Switch Settings and On-Board Links W914 W915 (DS to R) W951 (Y1 to Y2) Wiring Connections Thermostat DIP Switch (O to R) Two-Stage cation or Heat Pumps Cooling Harmony Dual Fuel DIP Switch 1 Intact Intact CONTROL HEAT PUMP L7742U...

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