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035-19671-001 Rev. A (0404)

2

Unitary Products Group

7.

NEVER . . .Store flammable materials of any kind near your fur-
nace. Gasoline, solvents, and other volatile liquids should be
stored only in approved containers outside your home. These
materials vaporize easily and are extremely dangerous.

8.

NEVER . . .Store cleaning materials near your furnace. Materials
such as bleaches, detergents, powdered cleansers, etc., can
cause corrosion of the heat exchangers.

9.

NEVER . . . Use the area around your furnace as a storage area
for items which could block the normal flow of air. This flow of air is
required for ventilation of the various furnace components.

INSTRUCTIONS FOR EXAMINING THE FURNACE 

INSTALLATION

It is the owner’s responsibility to ensure that an annual inspection of the
entire heating portion of the unit is made by a qualified service agency.
Examine the furnace as outlined below in steps “1 - 6” before each
heating season. Use Figure 3 for visual reference.

1.

Examine the heat exchanger, vent pipe, combustion air passes-
ges, vent connectors and chimney to be sure they are clear and
free of obstructions.

2.

Examine the vent pipe making sure it is firmly in place, that it
slopes slightly upward and is physically sound without holes and
all of the connections are secure.

3.

Examine the return-air duct connections to make sure they are
physically sound, sealed to the furnace casing, and the ducts ter-
minate outside the 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 sketch shown in Figure 2 as a compari-
son to the actual flame.

 FIGURE 1: 

Component Locations

FIRE OR EXPLOSION HAZARD

This furnace is designed and approved for use with Nat-
ural Gas and (LP) Propane Gas ONLY. DO NOT BURN
ANY LIQUID FUEL OR SOLID FUEL IN THIS FURNACE.

Burning any unapproved fuel will result in damage to the
furnace heat exchanger, which could result in Fire, Per-
sonal Injury, and/or Property Damage.

BLOWER

PRESSURE
SWITCH

BURNER
ASSEMBLY

GAS VALVE

VENT PIPE

INDUCER
ASSEMBLY

INDUCER
MOTOR

INTEGRATED
CONTROL

R

E

P

L

A

C

E

R

E

P

L

A

C

E

SCRE

W

SCRE

W

PM

C
HI

O
F
F

O
F
F

ON

ROLLOUT
SWITCH

ELECTRICAL
JUNCTION BOX

LIMIT CONTROL

SAFETY SHUTOFF
SWITCH

 FIGURE 2: 

Burner Flame Drawing

BLUE CONE PORTION OF FLAME SHOULD
ENTER HEAT EXCHANGER TUBE

 FIGURE 3: 

Furnace Examination Checkpoints

4 EXAMINE

FURNACE
CASING

6

5

3

4

3

1

6

EXAMINE
RETURN AIR
DUCT
CONNECTION

REMOVE
PANEL
TO EXAMINE
BURNER
FLAMES

EXTERNAL HEAT EXCHANGER INTERNAL

VENT COMBUSTION AIR PIPE. MUST

REMOVE PANEL TO EXAMINE.

EXAMINE ENTIRE
FURNACE CASING
SHOWN IN ALL
DRAWINGS

EXAMINE
RETURN AIR
DUCT
CONNECTION
(side or bottom)

REMOVE
PANEL
TO EXAMINE
BURNER
FLAMES

EXAMINE EXTERNAL
VENT PIPE

EXAMINE
FURNACE
CASING

BURNER DOOR

BLOWER DOOR

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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