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©

 2003 Lennox Industries Inc.

Corp. 0304−L4

G50UHi

Service Literature

Revised 10−2005

G50UHi Series Units

G50UHi series units are mid−efficiency gas furnaces used

for upflow or horizontal applications only, manufactured

with Lennox Duralok Plus

®

 heat exchangers formed of alu-

minized steel. G50UHi units are available in heating capac-

ities of 66,000 to 154,000 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. G50UHi model

units are equipped with the Lennox  SureLight

®

  silicon ni-

tride  ignition system and  blower control module. The blower

control module allows the G50Ui to maintain a constant

CFM over a wide range of operating static pressure. All units

use a redundant gas valve to assure safety shut−off as re-

quired by C.S.A.

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.

TABLE OF CONTENTS

Introduction

1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Specifications

2

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

High Altitude

3

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Blower Data

4

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Parts Identification

6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

I Unit Components

8

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

II  Installation

17

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

III Start Up

17

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

IV Heating System Service Checks

17

. . . . . . . . . . . . . . 

V Typical Operating Characteristics

20

. . . . . . . . . . . . . . 

VI Maintenance

20

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

VII Wiring and Sequence of Operation

22

. . . . . . . . . . . . 

VIII Troubleshooting 

28

. . . . . . . . . . . . . . . . . . . . . . . . . . . 

IMPORTANT

Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person-
al injury or loss of life. Installation and service must
be performed by a qualified installer, service agency
or the gas supplier.

 

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.

WARNING

Sharp edges.
Be careful when servicing unit to avoid sharp edges
which may result in personal injury.

Содержание G50UHi Series

Страница 1: ...ned 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 ma...

Страница 2: ...gle 44J22 Ten Pack 66K63 1 16 x 25 x 1 406 x 635 x 25 EZ Filter Base Catalog Number Ship Wt 73P55 6 lbs 3 kg 73P56 7 lbs 3 kg 73P56 7 lbs 3 kg Base Dimensions H x W x D 4 x 14 1 4 x 28 5 8 in 102 x 36...

Страница 3: ...8 m 15M22 15M22 LPG Propane Kit 0 7500 ft 0 2286 m 45L60 45L60 p 7501 10 000 ft 2286 3048 m 47M81 47M81 Horizontal Support Frame Kit Shipping Weight 56J18 18 lbs 8 kg 56J18 18 lbs 8 kg Relay Kit 56L68...

Страница 4: ...060 500 475 985 465 445 875 415 390 790 375 330 690 325 290 525 250 225 0 9 225 935 440 435 930 440 435 885 420 410 825 390 390 740 350 350 675 320 295 510 240 235 NOTES All air data is measured exter...

Страница 5: ...375 650 420 1075 505 290 0 4 100 2055 970 1015 1945 920 890 1825 860 775 1680 790 645 1525 720 545 1375 650 455 1075 505 310 0 5 125 2010 950 1025 1895 895 890 1810 855 810 1680 795 690 1515 715 580 1...

Страница 6: ...Page 6 FIGURE 1...

Страница 7: ...HORIZONTAL POSITION BLOWER ACCESS PANEL HEAT EXCHANGER ASSEMBLY BURNER ASSEMBLY COMBUSTION AIR INDUCER SURELIGHT CONTROL BOARD GAS VALVE BURNER ACCESS PANEL BLOWER ASSEMBLY PRIMARY LIMIT BLOWER CONTRO...

Страница 8: ...utions will help to avoid control exposure to electrostatic dis charge by putting the furnace the control and the technician at the same electrostatic poten tial Neutralize electrostatic charge by tou...

Страница 9: ...tion air inducer is energized When the differential in the prove switch is great enough the prove switch closes and a 15 second pre purge begins If the prove switch is not proven within 2 1 2 minutes...

Страница 10: ...NEOUS FAST FLASH SIMULTANEOUS FAST FLASH Normal operation signaled when heating demand initiated at thermostat SLOW FLASH ON Primary or secondary limit switch open Limit must close within 3 minutes or...

Страница 11: ...ic or electro mechanical thermostats without modification Each time power is applied to the furnace the ignition con trol performs a selfcheck The SureLight ignitor is made of durable silicon nitride...

Страница 12: ...ge to the ignitor until it finds the lowest amount of power that will provide a successful ignition This amount of power is used for 255 cycles On the 256th call for heat the control will again ramp d...

Страница 13: ...ge before re moving blower control module cover Failure to wait may cause personal injury or death Remove the cover panel from the module to access the se lector jumpers There are five selector pins i...

Страница 14: ...C Ramp A 6 Ignitor The SureLight ignitor is made of durable silicon nitride Ig nitor longevity is enhanced by controlling voltage to the ig nitor The board finds the lowest ignitor temperature which...

Страница 15: ...cut out from the side of the cabinet See figure 15 Use the two provided sheet metal screws to install the cut out on the top cap to cover the original flue outlet open ing Combustion Air Inducer Upfl...

Страница 16: ...ir blower and closes the gas valve The limit automatically resets when unit temperature returns to normal G50UHi 1 through 6 units use a surface type limit factory set to open at 125 F G50UHi 7 and la...

Страница 17: ...eywell Gas Valve Turn knob on gas valve clockwise to OFF Do not force See figure 18 7 Wait five 5 minutes to clear out any gas If you then smell gas STOP Immediately call your gas supplier from a neig...

Страница 18: ...n checked and adjusted check manifold pressure Move pressure gauge to outlet pres sure tap located on unit gas valve GV1 Checks of man ifold pressure are made as verification of proper regulator ad ju...

Страница 19: ...a tion Current passes from the sensor through the flame to ground to complete a safety circuit TABLE 17 Flame Signal in Microamps Ignition Control Normal Low Drop Out 97L48 0 61 0 21 0 60 0 20 69M15 0...

Страница 20: ...onnect the other end of manometer to the return duct as above For systems with non ducted returns leave the other end of the manometer open to the at mosphere 3 With only the blower motor running and...

Страница 21: ...aning is accomplished Reverse drill and slowly work the cable out of opening 8 Repeat procedure for each heat exchanger section 9 After each of the top heat exchanger sections has been cleaned insert...

Страница 22: ...Page 22 VII WIRING AND SEQUENCE OF OPERATION...

Страница 23: ...s into 5 minute Watchguard Pressure Switch delay Once S18 closes a 15 second pre purge follows 4 SureLight control A92 energizes ignitor A 20 second warm up period begins 5 Gas valve opens for a 4 sec...

Страница 24: ...WITH DELAY LED 1 OFF LED 2 SLOW FLASH Sequence holds until PROVE switch closes or thermostat resets control NO NO YES NO IS THERE PROPER GROUND IS VOLTAGE ABOVE 75 VOLTS LED 1 AND LED 2 ALTERNATING FA...

Страница 25: ...CER OFF INDOOR BLOWER OFF WITH DELAY LED 1 ALT SLOW FLASH LED 2 ALT SLOW FLASH IS 60 MINUTE RESET PERIOD COMPLETE YES 4 SECONDS YES HAS CONTROL RESET IGNITION SEQUENCE FOUR TIMES FLAME SIGNAL NORMAL S...

Страница 26: ...TOR AND SYSTEM FAN ENERGIZED AFTER DELAY COOL SPEED AND ELECTRONIC AIR CLEANER TERMINAL IS ENERGIZED Control board 69M15 2 second delay Control board 97L48 no delay COMPRESSOR OFF THERMOSTAT OPENS COO...

Страница 27: ...OPENS COMBUSTION AIR INDUCER AND HEATING ACCESSORY TERMINAL ARE DE ENERGIZED INDOOR BLOWER SWITCHES TO COOL SPEED THERMOSTAT OPENS INDOOR BLOWER SWITCHES TO CONTINUOUS BLOWER ELECTRONIC AIR CLEANER T...

Страница 28: ...pen ACTION 1 Manually reset the roll out switch by pushing the top button ACTION 2 Determine the cause of the roll out switch activation before leaving furnace code LED 1 O 1 2 2 Roll out switch failu...

Страница 29: ...1 Alternating Fast Flash LED 2 Alternating Fast Flash 2 1 2 Broken or failed ignitor ACTION 1 Unplug ignitor and read resistance across ignitor If resistance does not read be tween 10 9 and 19 7 ohms...

Страница 30: ...with a heating demand Diagnostic lights flash the pressure switch failure code 2 5 minutes after heating demand 4 1 2 Prove switch does not close due to obstructions in the pressure lines ACTION 1 Re...

Страница 31: ...ure switch code LED 1 Off LED 2 Slow Flash 6 1 1 Low pressure differential at the prove switch ACTION 1 Check for restricted exhaust vent Remove all blockage ACTION 2 Check for proper vent sizing See...

Страница 32: ...ash 6 3 3 Insufficient flow through the heat exchanger caused by a sooted or restricted heat exchanger ACTION 1 Check for sooting deposits or other restrictions in the heat exchanger assembly Clean as...

Страница 33: ...lash 7 1 2 Sense rod is contaminated ACTION 1 Check sense rod for contamination or coated surface Clean the sense rod with steel wool or replace sensor DO NOT USE SAND PA PER TO CLEAN ROD SAND PAPER W...

Страница 34: ...t lead from ACB Cool to 120HOT terminal D Make sure blower access panel is replaced properly to close door interlock switch and energize SureLight control board D Repeat with ACB Heat and ACB Low lead...

Страница 35: ...ize SureLight control board D Check for proper demand from thermostat Is motor operating properly Recheck all wiring connections CHECK BLOWER CONTROL MODULE Proper blower control module must be instal...

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