Lennox 80UGH Unit Information
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Lennox 80UGH Unit Information

80uhg series mid−efficiency gas furnaces
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Service Literature
80UHG series units are mid−efficiency gas furnaces used
for upflow or horizontal applications only, manufactured
with tubular heat exchangers formed of aluminized steel.
80UHG units are available in heating capacities of 45,000
to 120,000 Btuh and cooling applications up to 5 tons. Refer
to Engineering Handbook for proper sizing.
Units are factory equipped for use with natural gas. Kits are
available for conversion to LPG operation. 80UHG−1 model
units use electronic (direct spark) ignition. 80UHG−2 and −3
model units are equipped with the Lennox SureLight silicon
nitride ignition system. The 80UHGX unit meets the Califor-
nia Nitrogen Oxides (NO
x
sonal Efficiency requirements. All units use a redundant gas
valve to assure safety shut−off as required by A.G.A. or
C.G.A. Units may be installed in upflow or horizontal position.
All specifications in this manual are subject to change. Pro-
cedures outlined in this manual are presented as a recom-
mendation 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 recommended only and do not constitute
code.

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Parts Identification
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) Standards and California Sea-
6−15
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19−20
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21−28
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29−34
Corp. 9728−L12
Revised 01−2002
1
2
3−4
4
5−6
15
15
18
Page 1
80UHG
© 1999 Lennox Industries Inc.
Litho U.S.A.

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Summary of Contents for Lennox 80UGH

  • Page 1: Table Of Contents

    Units are factory equipped for use with natural gas. Kits are available for conversion to LPG operation. 80UHG−1 model units use electronic (direct spark) ignition. 80UHG−2 and −3 model units are equipped with the Lennox SureLight silicon nitride ignition system. The 80UHGX unit meets the Califor- nia Nitrogen Oxides (NO ) Standards and California Sea- sonal Efficiency requirements.

  • Page 2: Specifications

    SPECIFICATIONS Model No. 80UHG2(X)-45 80UHG2(X)-60 80UHG3(X)-60 80UHG2(X)-75 80UHG3(X)-75 80UHG4(X)-75 Input Btuh (kW) 45,000 (13.2) 60,000 (17.6) 75,000 (22.0) Output Btuh (kW) 36,900 (10.8) 49,200 (14.4) 61,700 (18.1) 61,700 (18.1) A.F.U.E. 80.1% 80.5% 80.1% 80.0% California Seasonal Efficiency 75.4% 76.4% 75.9% 76.8% 76.8% 76.3%...

  • Page 3: Blower Data

    BLOWER DATA 80UHG2−45, 80UHG2−60 AND 80UHG2−75 BLOWER PERFORMANCE Air Volume at Various Blower Speeds External Static External Static Pressure High Medium-High Medium-Low in. w.g. 1270 1245 1220 1195 1170 1140 1110 1060 NOTE All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished) in place. Also see Filter Air Resistance table 80UHG3−60 AND 80UHG3−75 BLOWER PERFORMANCE Air Volume at Various Blower Speeds External Static...

  • Page 4: High Altitude

    BLOWER DATA 80UHG4/5-100 AND 80UHG4/5-120 BLOWER PERFORMANCE Air Volume at Various Blower Speeds External Static External Static Pressure High Medium-High Medium Medium-Low in. w.g. 2450 1155 2160 1020 1970 1700 1500 2440 1150 2155 1015 1965 1695 1500 2430 1145 2150 1015 1960...
  • Page 5 VENT ADAPTER 80UHG PARTS IDENTIFICATION CABINET TOP HEAT EXCHANGER ASSEMBLY FLUE BOX COMBUSTION AIR PROVE INDUCER SWITCH 80UHG CABINET FRONT ACCESS PANEL BURNER ASSEMBLY TRANSFORMER CONTROL BOARD SECONDARY LIMITS CABINET BOTTOM BLOWER ASSEMBLY DOOR INTERLOCK SWITCH FIGURE 1 HEATING COMPONENTS (shown in horizontal position) PRIMARY LIMIT ROLLOUT SWITCH (2) COMBUSTION AIR...

  • Page 6: I Unit Components

    80UHG BURNER ASSEMBLY (shown in upflow position) −2 MODEL SHOWN SURELIGHT ROLLOUT IGNITOR SWITCHES BURNER BOX VEST PANEL UPPER BURNER MOUNTING RAIL LOWER BURNER MOUNTING RAIL FLAME BURNER SENSOR HEAT EXCHANGER PRIMARY LIMIT Back ORIFICE Left GAS VALVE Right Front BURNER BOX MANIFOLD Bottom...
  • Page 7 3− Furnace Control (A3) a−Electronic Ignition (See Figure 5) On a call for heat the SureLight control monitors the com- 80UHG−2, −3 Models bustion air inducer pressure switch. The control will not be- 80UHG−2 and −3 model units are equipped with the Len- gin the heating cycle if the prove switch is closed (by−...
  • Page 8 The SureLight board is equipped with two LED lights for troubleshooting. The diagnostic codes are listed below in table 3. TABLE 3 DIAGNOSTIC CODES MAKE SURE TO ID LED’S CORRECTLY: REFER TO INSTALLATION INSTRUCTIONS FOR CONTROL BOARD LAYOUT. LED #1 LED #2 DESCRIPTION Power −...
  • Page 9 TABLE 4 SURELIGHT INTEGRATED CONTROL BOARD TERMINAL DESIGNATIONS COOL−H Blower − Cooling Speed (120VAC) HEAT−H Blower − Heating Speed (120VAC) EAC−H Electronic Air Cleaner (120VAC) HUM−H Humidifier (120VAC) XFMR−H Transformer (120VAC) LINE−H Input (120VAC) LINE−N Input (Neutral) XFMR−N HUM−N Humidifier (Neutral) EAC−N Electronic Air Cleaner (Neutral) XFMR−N...
  • Page 10 5− Furnace Control (A3) 80UHG−1 Model when no voltage should be present, the control de-energizes the combustion air inducer which terminates voltage to the 80UHG units are equipped with an integrated ignition/blower valve. The system goes into hard lock-out which is reset only control (EGC-2) which controls ignition, safety circuits, blower operation, fan off timing, and allows for thermostat by removing power to the unit.
  • Page 11 DIAG #1 and DIAG #2. The codes are given in Pressure Switch Watchguard, table 5. Flash pressure switch opened during operation. A slotted edge connector is also provided for the Lennox Alternate Watchguard, burners Alternate Flash Diagnostic Module (part number 11K75). See figure 10. Flash failed to ignite.
  • Page 12 TABLE 6 SUPPLY AIR BLOWER BLOWER CONTROL A15 TERMINAL DESIGNATIONS AND SECONDARY LIMITS SECONDARY Terminal LIMITS (S21) Designation Type Function (See fig. 10) Screw Strip 24VAC to Thermostat (Red) Manual Fan Input from Thermostat Back Screw Strip (Green) Left Heat Demand Input from Thermostat Screw Strip Right (White)
  • Page 13 (figures 15 and 16) is located on the point will be printed on the limit. valve. LPG changeover kits are available from Lennox. Kit s include burner orifices and a gas valve regulator conversion kit. Page 13...
  • Page 14 HONEYWELL VR8205 SERIES GAS VALVE WHITE RODGERS 36E SERIES GAS VALVE MANIFOLD MANIFOLD MANIFOLD PRESSURE PRESSURE PRESSURE ADJUSTMENT OUTLET ADJUSTMENT SCREW SCREW MANIFOLD PRESSURE OUTLET GAS VALVE SHOWN IN OFF POSITION GAS VALVE SHOWN IN OFF POSITION FIGURE 16 FIGURE 15 TYPICAL BURNER/ELECTRODE ORIENTATION 23/32 in.

  • Page 15: Installation

    B−Heating Start-Up PROVE SWITCH COMBUSTION AIR INDUCER PROVE SWITCH WARNING Normally Open Closes on Negative Pressure Shock and burn hazard. 80UHG−1 units are equipped with a direct spark igni- tion system. Do not attempt to light manually. 1 − STOP! Read the safety information at the beginning of this section.

  • Page 16: Heating System Service Checks

    IV−HEATING SYSTEM SERVICE CHECKS through Lennox under part number 31B2001. See Corp. 8411−L10, for further details. A−A.G.A./C.G.A. Certification Do not use matches, candles, flame or any other source of All units are A.G.A. and or C.G.A. design certified without ignition to check for gas leaks.
  • Page 17 Start unit and allow 5 minutes for unit to reach #78H5401 available from (PART #78H5401) steady state. Lennox Repair Parts) is 2 − While waiting for the unit to stabilize, notice the flame. required measure Flame should be stable and should not lift from burner.

  • Page 18: Typical Operating Characteristics

    C−External Static Pressure WARNING 1 − Tap locations shown in figure 23. Fire and explosion hazard. 2 − Punch a 1/4" diameter hole STATIC PRESSURE These instructions MUST be followed exactly. in supply and return air ple- TEST Can cause a fire or explosion resulting in property nums.

  • Page 19: Maintenance

    VI−MAINTENANCE BLOWER SPEED TAP SELEC- TION At the beginning of each heating season, the system HARNESS Leaded Motors should be checked as follows: CONNECTOR A−Filters Return air filter is not supplied with unit. See Optional Ac- cessaries section in this manual for filter and rack size. A filter must be used in order to ensure long life and proper operation.
  • Page 20 2 − Check for correct voltage. 1 − Check and clean blower wheel. 3 − Check amp−draw on blower motor. 2 − Motors used on the Lennox 80UHG series units are permanently lubricated and need no further lu- brication. Page 20...

  • Page 21: Wiring And Sequence Of Operation

    VII− Wiring and Sequence of Operation 80UHG−1 MODEL WITH EGC CONTROL (SEE FLOW CHARTS ON THE FOLLOWING TWO PAGES): 1 − When disconnect is closed, 120V is routed through door 5 − When S18 closes, assuming primary limit (S10) and interlock switch (S51) to feed the line voltage side of the secondary limit (S21) are closed, a 15 second pre−purge ignition control (A3) and transformer T1 primary.
  • Page 22 80UHG−1 HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE GAS VALVE OFF. COMB. INDUCER ON. INDOOR CONTROL MAIN POWER ON" BLOWER ON HEAT SPEED. SEQUENCE HOLDS UNTIL NO FLAME SENSED OR MAIN POWER IS INTERRUPTED FLAME OFF? AND RESET. DIAG. CODE: 1− FLASHING; 2−OFF (FLAME SENSED WITHOUT VALVE ENERGIZED) CONTROL SELF−CHECK OKAY? GAS VALVE, COMB.
  • Page 23 80UHG−1 COOLING SEQUENCE OF OPERATION LED: Slow flash rate. REMAINS UNCHANGED THROUGHOUT COOLING CYCLE. THERMOSTAT CALLS FOR COOLING. COMPRESSOR CONTACTOR AND SYSTEM FAN ENERGIZED AT COOLING SPEED AFTER 1 SECOND DELAY. ACC TERMINAL ENERGIZED. THERMOSTAT OPENS. COMPRESSOR OFF. SYSTEM FAN AND ACC TERMINAL OFF AFTER 0 SECONDS.
  • Page 24 80UHG−2 MODEL WITH SURELIGHT CONTROL 1 − When there is a call for heat, W1 of the thermostat en- 5 − Gas valve opens for a 4−second trial for ignition (igni- ergizes W of the furnace control with 24VAC. tor will remain energized for the first second). 2 −...

  • Page 25: Heating Sequence Of Operation

    HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. POWER ON INDOOR BLOWER DELAY OFF. LED #1 ON LED #2 ON CONTROL SELF−CHECK OKAY? (RESET CONTROL BY TURNING MAIN POWER OFF.) IS POLARITY REVERSED? POLARITY REVERSED.
  • Page 26 HEATING SEQUENCE CONTINUED NORMAL HEATING MODE ABNORMAL HEATING MODE 15-SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. IS VOLTAGE ABOVE 75 VOLTS? LEDS SIGNAL IGNITOR WARM-UP −− 20 SECONDS. ALTERNATING IS THERE A PROPER GROUND? FAST FLASH 4-SECOND TRIAL FOR IGNITION. IS IGNITOR INTACT AND CONNECTED? GAS VALVE OPENS.
  • Page 27 COOLING SEQUENCE OF OPERATION NORMAL COOLING MODE ABNORMAL COOLING MODE 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 28 SURELIGHT CONTROL CONTINUOUS HEAT SPEED FAN SEQUENCE OF OPERATION LED: SLOW FLASH RATE REMAINS UNCHANGED THROUGHOUT SEQUENCE. MANUAL FAN SELECTION MADE AT THERMOSTAT. CONTROL (G) ENERGIZES SYSTEM FAN AT HEAT−H HEAT SPEED. EAC−H TERMINAL IS ENERGIZED. HUM−N TERM. ENERGIZES THERMOSTAT CALLS FOR HEAT (W). WITH COMB.

  • Page 29: Surelight Troubleshooting Guide

    VIII−Troubleshooting−SureLight Control SURELIGHT − TROUBLE SHOOTING GUIDE UPON INITIAL POWER UP, REMOVE ALL THERMOSTAT DEMANDS TO THE UNIT PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE Condition Possible Cause Corrective Action / Comments 1.1.1 ACTION 1 −...
  • Page 30 PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE Condition Possible Cause Corrective Action / Comments ACTION 1 − Check that the unit is properly 1.5.1 ground. − Diagnostic lights flash the improper ACTION 2 − Install a proper main ground to the Improper ground to the unit.
  • Page 31 PROBLEM 2: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR INDUCER DOES NOT ENERGIZE (CONT.). Condition Possible Cause Corrective Action/Comments − Unit operates with a cooling and con- 2.3.1 ACTION 1 − Check for correct wiring and loose tinuous fan demand.
  • Page 32 PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER ENERGIZES, IGNITOR IS ENERGIZED. Condition Possible Cause Corrective Action/Comments ACTION 1 − Check line pressure at the gas 4.1.1 valve. Pressure should not exceed 13" WC for −...
  • Page 33 PROBLEM 5: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.) Condition Possible Cause Corrective Action/Comments ACTION 1 − Check that the manifold pressure matches value listed on nameplate. See installa- − Combustion air inducer energizes 5.3.1 tion instructions for proper procedure. with a heating demand.
  • Page 34 PROBLEM 6: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE Condition Possible Cause Corrective Action/Comments 6.1.1 ACTION 1 − Check the sensor rod for proper location on the burner. Properly locate the sen- − Unit operates correctly but the Sensor rod is improperly located on sor rod or replace if rod cannot be located cor- diagnostic lights flash low flame the burner.

This manual is also suitable for:

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