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035-19671-001 Rev. A (0404)

USER’S INFORMATION,
MAINTENANCE AND 
SERVICE MANUAL

MODELS: 

P*DU / G8D-UH / L8D-UH

(Two Stage Upflow / LoNOx)

EFFICIENCY
RATING
CERTIFIED

This product was manufactured
in a plant whose quality system
is certified/registered as being
in conformity with ISO 9001.

The manufacturer recommends that the user read all sec-
tions of this manual and keep the manual for future refer-
ence.

 

SECTION I: USER’S INFORMATION

SAFETY

1.

The furnace area must be kept clear and free of combustible mate-
rials, gasoline and other flammable vapors and liquids.

2.

Insulating materials may be combustible. The furnace must be
kept free and clear of insulating materials. The furnace area must
be examined when installed in an attic or other insulated space or
when insulation is added to be sure that the insulation material has
been kept away from the furnace.

3.

The furnace needs air for combustion in order to operate properly
and safely. Do not block or obstruct air openings on the furnace, air
openings to the area where the furnace is installed, or spaces
around the furnace.

4.

Follow the instructions exactly as shown on the OPERATING
INSTRUCTION LABEL or the Start-up and Shutdown Instructions
on Page 3 of this manual when lighting the furnace or turning the
furnace off.

5.

Should the gas supply fail to shut off or if overheating occurs, shut
off the gas valve to the furnace before shutting off the electrical
supply.

6.

Do not use this furnace if any part has been under water. A flood-
damaged furnace is extremely dangerous. Attempts to use the fur-
nace can result in fire or explosion. A qualified service agency
should be contacted to inspect the furnace and replace all gas con-
trols, control system parts, electrical parts that have been wet or
the furnace if deemed necessary.

FIRE OR EXPLOSION HAZARD - 

Failure to follow safety

warnings exactly could result in serious injury, death, or prop-
erty damage.

— 

Do not store or use gasoline or other flammable

vapors and liquids in the vicinity of this or any other
appliance.

—  

WHAT TO DO IF YOU SMELL GAS:

Do not try to light any appliance.

Do not touch any electrical switch; do not use any phone 
(including cell phone) in your building.

Leave the building immediately.

Immediately call your gas supplier from a neighbor’s 
phone. Follow the gas supplier’s instructions.

If you cannot reach your gas supplier, call the fire depart-
ment.

— 

 Installation and service must be performed by a quali-

fied installer, service agency or the gas supplier.

CONTACT INFORMATION

Go to website at www.york.com click on “contact”, then click on “contact form” and follow the instructions.

Contact us by mail:

York International

Consumer Relations

5005 York Drive

Norman, OK 73069

TABLE OF CONTENTS

CONTACT INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

USER’S INFORMATION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

SAFETY   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
INSTRUCTIONS FOR EXAMINING THE FURNACE 
INSTALLATION   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
HOW YOUR GAS FURNACE WORKS   . . . . . . . . . . . . . . . . . . . . . . 3
START-UP AND SHUTDOWN INSTRUCTIONS  . . . . . . . . . . . . . . . 3

Read the Instructions Below Before Trying to Start the Furnace . . 3
Operating Instructions: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
To Turn Off the Appliance: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

FURNACE USER MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Air Filters  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Removing Filters   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Blower Care  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Motor Lubrication  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SERVICE AND MAINTENANCE MANUAL . . . . . . . . . . . . . . . . . . . . . 5

SAFETY SECTION  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

FURNACE MAINTENANCE SECTION  . . . . . . . . . . . . . . . . . . . . . . .5
SEQUENCE OF OPERATION   . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Continuous Blower  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Intermittent Blower - Cooling   . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Heating Cycle  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Hot Surface Ignition System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

FURNACE CLEANING SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Burner Removal/Cleaning   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Cleaning the Heat Exchanger   . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

TROUBLESHOOTING   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
FURNACE CONTROL DIAGNOSTICS  . . . . . . . . . . . . . . . . . . . . . . .6

REPLACEMENT PARTS LIST   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

FIELD INSTALLED ACCESSORIES - NON-ELECTRICAL   . . . . . .10
FIELD INSTALLED ACCESSORIES - ELECTRICAL  . . . . . . . . . . .10

REPLACEMENT PART CONTACT INFORMATION . . . . . . . . . . . . .10
WIRING DIAGRAM   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
LIMITED WARRANTY  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Summary of Contents for G8D-UH

Page 1: ...electrical parts that have been wet or the furnace if deemed necessary FIRE OR EXPLOSION HAZARD Failure to follow safety warnings exactly could result in serious injury death or prop erty damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance WHAT TO DO IF YOU SMELL GAS Do not try to light any appliance Do not touch any electrical s...

Page 2: ...space containing the furnace 4 Examine the furnace casing making sure the physical support is sound without sagging cracks or gaps Examine the furnace base making sure it is physically sound without cracks gaps or sagging and has a good seal 5 Examine the furnace casing for obvious signs of deterioration 6 Examine the burner flames to make sure they are in good adjust ment Refer to the pictorial s...

Page 3: ...part of the control system and any gas control which has been under water Operating Instructions 1 STOP Read the safety information above 2 Set the thermostat to the lowest setting 3 Turn off all electric power to the appliance 4 Remove burner door 5 Move gas control switch to the OFF position Do not force See Figure 4 6 Wait five 5 minutes to clear out any gas If you then smell gas STOP Follow B ...

Page 4: ...ters by using brackets with the number two 2 D If the air filters are on both sides of the furnace then you have a two sided return You must replace both air filters Table 1 will indicate 2 filters by using brackets with the number two 2 3 After you determine the cabinet size and what return configuration you have look up the recommended filter size from Table 1 Removing Filters Internally Mounted...

Page 5: ...en using a 2 Stage thermostat the Timer should be discon nected The Inducer Motor is shifted to high speed by the control closing the contacts of 2LP The High Fire Pressure Switch The Control checks that 2LP is closed The Gas Valve is energized on 2nd Stage High Fire The Control simultaneously de energizes the Heat Low relay and energizes the Heat High relay providing 120 Volts AC to a different s...

Page 6: ...ess doors 2 Remove blower assembly mounting screws and slide the blower assembly out of the slots in the deck If the two shipping screws were not previously removed also remove and discard these two screws located on each front corner of the blower assembly 3 Loosen the blower wheel set screw that secures the blower wheel to the blower motor shaft 4 Remove the motor mount bolts 5 Slide the variabl...

Page 7: ...placement gaskets be avail able before removing vent motor 1 Remove six mounting screws that hold the vent motor to the restrictor plate The surface is gasketed and gasket can be reused if it is carefully removed It is necessary to remove this assembly to gain access to the restrictor plate mounting holes The assembly may be vacuumed if cleaning is necessary If any vent assembly parts are damaged ...

Page 8: ...Dirty Filter Improperly sized duct system Incorrect blower speed selection Incorrect firing rate Faulty blower motor Faulty Control 6 Flash Reason 1LP has opened five times during one call for heat Effect Control enters Soft Lockout It will automatically reset and try again after 1 hour Causes Restricted vent system Vent system that exceeds specifications High wind 7 Flash Reason Flame rectificati...

Page 9: ...OW INDUCER LOW STAGE PRESSURE SWITCH HSI 1ST STAGE MAIN VALVE FLAME SENSE LOW CIRCULATOR HEAT SPEED 1ST STAGE LOW PRESSURE SWITCH CLOSE RECOGNITION HSI WARM UP 17 SEC IGNITION ACTIVATION PERIOD 4 SEC TRIAL FOR IGNITION 7 SEC INTER PURGE 60 SEC HSI WARM UP 27 SEC IGNITION DEACTIVATION PERIOD 3 SEC HEAT FAN DELAY ON 30 SEC BURN TIME POST PURGE 15 SEC HEAT FAN DELAY OFF SELECTABLE 60 90 120 180 SEC O...

Page 10: ...035 19671 001 Rev A 0404 10 Unitary Products Group SECTION III REPLACEMENT PARTS LIST 28 38 39 32 27 3 30 26 5 10 9 22 24 6 20 11 2 37 29 8 23 12 7 35 17 19 21 13 1 16 15 25 4 41 12A 7 35 24 36 12 19 11 ...

Page 11: ...N GAS 20 BRACKET IGNITER 21 DECK BLOWER Rear 22 DECK FRONT 23 HEAT EXCHANGER ASS Y 24 MANIFOLD GAS 25 PANEL ACCESS BURNERS 26 PAN BASE 27 PANEL FRONT Blower 28 PANEL TOP 29 WRAPPER INSULATED 30 CHANNEL TOE PLATE 31 FILTER 32 PLUG WINDOW CLEAR 875 33 RETAINER FILTER 34 CLIP SPRING FILTER RETAINER 35 BRACKET ROLL OUT SWITCH MISCELLANEOUS 36 ORIFICE BURNER Natural 45 37 PLATE RESTRICTOR N Model PLATE...

Page 12: ...stage Heat One Stage Cool ALL MODELS 2TB17700424 THERMOSTAT Subbase for 2TH13700424 ALL MODELS 2ET07700324 THERMOSTAT Programmable ALL MODELS 2ET07700224 THERMOSTAT Deluxe Programmable One stage Heat One stage Cool with subbase ALL MODELS REPLACEMENT PART CONTACT INFORMATION This is a generic parts list To request a complete parts list refer to the contact information below Visit our website at ww...

Page 13: ...035 19671 001 Rev A 0404 Unitary Products Group 13 SECTION IV WIRING DIAGRAM FIGURE 9 Wiring Diagram ...

Page 14: ...035 19671 001 Rev A 0404 14 Unitary Products Group NOTES ...

Page 15: ...035 19671 001 Rev A 0404 Unitary Products Group 15 ...

Page 16: ...applies only to products installed in the United States and Canada EXCLUSIONS This warranty does not cover any 1 Shipping labor or material charges 2 Damages resulting from transportation installation or servicing 3 Damages resulting from accident abuse fire flood alteration or acts of God tampering altering defacing or removing the product serial number will serve to void this warranty 4 Damages ...

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