Unitary products group G8C 50, L8C 50 Installation Instructions Manual
INSTALLATION
INSTRUCTIONS
MODELS: G8C 50 THRU 125 INPUT
ALL POSITION AUTOMATIC
IGNITION FURNACES
Supersedes: Nothing 650.66-N2V (9/98)
035-15815-401
& L8C 50 THRU 125 INPUT
TABLE OF CONTENTS
GENERAL INFORMATION ......................................1
FURNACE SPECIFICATIONS.................................2
PRE-INSTALLATION INSPECTION........................3
CODE COMPLIANCE ..............................................3
INSTALLATION POSITION......................................3
CONVERSION INFORMATION...............................3
TO CONVERT FROM DOWNFLOW TO UPFLOW
CONFIGURATION ................................................... 4
TO CONVERT FROM UPFLOW TO DOWNFLOW
CONFIGURATION ................................................... 5
FURNACE LOCATION.............................................5
COMBUSTION AND VENTILATION AIR.................6
FURNACE SIZING AND DUCT SYSTEM DESIGN.8
RETURN AIR AND FILTERS ...................................8
GAS PIPING...........................................................10
VENTING (CATEGORY I)......................................12
SIDEWALL VENTING ............................................15
ELECTRICAL WIRING...........................................15
WIRING DIGRAM...................................................17
PRE-OPERATIONAL CHECKS.............................18
SEQUENCE OF OPERATION...............................18
FURNACE OPERATION........................................18
INSTALLATION CHECKS......................................19
SERVICE INSTRUCTIONS....................................21
REPLACEMENT PARTS........................................21
GENERAL INFORMATION
These instructions are for the use of qualified
individual specially trained and experienced in
installation of this type equipment and related
system components.
Installation and service personnel are required
by some states to be licensed. Persons not
qualified shall not install this equipment nor
interpret these instructions
NOTE: The words "shall" or "must" indicate a
requirement which is essential to
satisfactory and safe performance.
The words "should" or "may" indicate a
recommendation or advice which is not
essential and not requ ired but which m ay be
useful or helpful.
NOTE: After installing the furnace, show the user
how to turn off the electric al power and gas
supply to the furnace. Make sure that the
user understands the importance of
following all safet y rules.
FURNACE SPECIFICATIONS
BTUH
INPUT
50,000 17-1/2 10 x 8 30-60 1200 160 1/3 3” 2802-5521
75,000 17-1/2 10 x 8 35-65 1200 165 1/3 4” 2802-5521
75,000 21 10 x 10 30-60 1600 160 1/2 4” 2804-5521
100,000 21 10 x 10 40-70 1600 170 1/2 4” 2804-5521
100,000 24-1/2 (2) 10 x 6 35-65 2000 165 3/4 4” 2805-5521
125,000 24-1/2 (2) 10 x 6 40-70 2000 170 3/4 5” 2805-5521
* All models are supplied with 3” vent connec tions. An installer supplied trans ition to 4” or 5” diameter m ust be
used where necessary.
FURNACE
WIDTH
A
BLOWER
WHEEL
SIZE
TEMP.
RISE
°
F
CFM
HIGH @
0.5” W.C.
MAX
OUTLET
TEMP. °F
MOTORHPVENT
DIA.
DOWNFLOW
SUB-BASE
ABCDEFGHJ
17-1/2
21
24-1/2
FIGURE 1 – FURNACE DIMENSIONS AND SPECIFICATION
2
16-1/2
20
23-1/2
20-3/8
20-3/8
20-3/8
20
20
20
16
19-1/2
23
14-1/2
18
21-1/2
18-5/8
18-5/8
18-5/8
15-1/8
18-5/8
22-1/8
19
19
19
PRE-INSTALLATION INSPECTION
Inspect the shipping container and furnace for any
evidence of shipping damage.
If furnace damage is found, notify frei ght carrier and
file claim.
NOTE: Some models are equipped with a shipping
strap on the blower motor shaft which
supports the blower motor during shipping.
This strap must be removed before the
furnace is operated f or the first time. It can
be removed by removing the two fastening
screws.
CODE COMPLIANCE
The furnaces described in these instructions are
design certified b y the American Gas Ass ociation to
be in compliance with the latest edition of American
National Standard Z21.47. In Canada, these
furnaces are design certified by the Canadian Gas
Association to be in compliance with the latest
edition of CAN/CGA 2.3.
These furnaces are forced air type and may be
utilized for indoor installation in manufactured
buildings (modular only), or buildings constructed on
site. These furnaces ar e not certified for ins tallation
in mobile homes, trailers or recreational vehicles.
The installer must conform to all state, local and
provincial building codes when installing these
appliances. In the absence of state, local or provincial codes, these furnaces and related equipment
must be installed in accordanc e with the l atest is sue
of the following:
NATIONAL FUEL GAS CODE - ANSI Z223.1
NATIONAL ELECTRICAL CODE, ANSI/NFPA 70.
Applicable codes ta ke precedence over any rec ommendation made in these instructions.
In Canada, the installer must conform to the
CAN/CGA-B149 Installation Codes, the Canadian
Electrical Code, Part I, CSA C22.1, local plumbing or
waste water codes, and other applicable local
codes.
INSTALLATION POSITION
This furnace may be insta lle d in a n upflow, downflow
or horizontal position. Depending on the configuration shipped from the fac tory, it may be necessary to
convert the furnace fr om downflow t o upflow or fr om
upflow to downflow configuration. Use conversion
instructions starting on Page 3.
CONVERSION INFORMATION
This furnace may be shipp ed in either the upflo w or
the downflow configuration. To convert from upflow
to downflow or vice-versa it is necessary only to
exchange the top and bottom casing caps and to
rotate the vent blow er 180 degrees. Us e the s tep by
step instructions on next page.
3
FIGURE 2 – UPFLOW/HORIZONTAL FIGURE 3 – DOWNFLOW/HORIZONTAL
CONFIGURATION CONFIGURATION
TO CONVERT FROM DOWNFLOW TO
UPFLOW CONFIGURATION
1. Lay the furnace on its back.
2. Remove the front door.
3. Remove the seven she et metal screws that are
used to fasten the top cap to the casing. Remove the top cap and save the screws.
4. Remove the four sheet metal screws that are
used to fasten the bottom cap to the casing.
Remove the bottom cap and save the screws.
5. Unplug the vent blower wires.
6. Disconnect the pressure hose from the vent
blower.
7. Remove the four machine scre ws that f asten t he
vent blower to the vent pan and save the
screws. Leave the gasket in place on the pan.
8. Remove the two extra machine screws in the
vent pan front and save the screws.
9. Rotate the vent blower and transition 180° so
that its outlet points t o the outlet air end of the
furnaces as shown in Figure 2.
4
10. Line up the v ent blower m ounting holes with th e
holes in the vent pan and screw it into place.
Use the same machine screws that held the vent
blower in place previously.
11. Install the t wo extra machine screws in the two
open holes in the fr ont of the vent pan ( See Figure 2).
12. Plug in the vent motor wires.
13. Plug the pressure hose into the vent blower.
14. Remove the rectangular knockout in the center
of the top cap (See Figure 5.)
15. Install the top cap at the same end of the
furnace as the vent blower, using the sheet
metal screws saved earlier (See Figure 2).
16. Install the bottom cap on the bottom of the
furnace using the sheet metal screws saved
earlier (See Figure 2).
17. The conversion is now complete. The furnace
may now be installed in the upflow positio n or in
the horizontal position on either side.
TO CONVERT FROM UPFLOW TO
DOWNFLOW CONFIGURATION
1. Lay the furnace on its back.
2. Remove the front door.
3. Remove the seven she et metal screws that are
used to fasten the top cap to the casing.
4. Remove the four sheet metal screws that are
used to fasten the bottom cap to the casing.
Remove the bottom cap and save the screws.
5. Unplug the vent blower wires.
6. Disconnect the pressure hose from the vent
blower.
7. Remove the four machine scre ws that f asten t he
vent blower to the vent pan and save the
screws. Leave the gasket in place on the vent
pan.
8. Remove the two extra machine screws in the
vent pan front and save the screws.
9. Install the cast aluminum transition on the vent
blower, using the three screws supplied on the
vent blower (See Figure 4).
13. Plug in the vent motor wires.
14. Plug the pressure hose into the vent blower.
15. Remove the r ound knockout at the right side of
the top cap (See Figure 5).
FIGURE 5 – TOP CAP
16. Install the to p cap at t he oppos ite end of furnac e
from the vent blower, using the seven sheet
metal screws saved earlier (See Figure 3).
17. Install the bottom cap on the bottom of the
furnace using the sheet metal screws saved
earlier (See Figure 3).
18. The conversion is now complete. The furnace
may now be installed in the downflow posit ion or
in the horizontal position on either side
FIGURE 4 – VENT BLOWER
10. Rotate the vent blower 180º so that its outlet
points toward the inlet air end of the furnace
(See Figure 3).
11. Line up the v ent blower m ounting holes with th e
holes in the vent pan and screw it into place.
Use the same machine screws that held the vent
blower in place previously.
12. Install the t wo extra machine screws in the two
open holes in the fr ont of the vent pan ( See Figure 3).
FURNACE LOCATION
This furnace is design certified for installati on as an
upflow, downflow furnace or horizontal furnace on
either side in an alcove, closet, basement, attic,
garage or utilit y room. It is certifie d only for use i n a
home constructed on-site or a manufactured home
completed at the fin al site. This furnace is not des i gn
certified to be installed out doors, in a mobile hom e,
trailer or recreational vehicle.
The furnace should be located as close to the
chimney or vent as possible and as close to the
center of the warm air distribution system as
possible.
When the furnace is installed in a residentia l garage
it must be located and installed such that it will be
protected from damage by vehicles. The furnace
must be installed s o that the burners are a m inim um
of 18" above the floor.
Clearances to Combustible Materials
Proper clearances f rom the furnace to any c ombustible materials must be maintained. These required
minimum clearances are shown below and on a
label in the furnace.
5
Minimum Clearances – Upflow
Front: ........................................ 2 inches
Back:.......................................... 0 inches
Sides:......................................... 0 inches
Top............................................. 1 inch
B-1 Vent:.................................... 1 inch
Single-wall Vent:........................ 6 inches
Floor........................................... com bus tible
Minimum Clearances – Downflow
Front: ......................................... 2 inches
Back:.......................................... 0 inches
Sides:......................................... 0 inches
Top............................................. 1 inch
B-1 Vent:.................................... 1 inch
Single-wall Vent:........................ 6 inches
Floor........................................... non-c ombustible
For installation on combustible flooring only when
installed on the s pecial downflow sub-bas e listed in
the Specifications Table on page 2.
Minimum Clearances – Horizontal
Front: ......................................... 2 inches
Back:.......................................... 0 inches
Ends:.......................................... 1 inch
Top............................................. 1 inch
B-1 Vent:.................................... 1 inch
Single-wall Vent:........................ 6 inches
Floor........................................... com bus tible
When the furnace is installed in the horizontal
position, line contact is permissible. T he line form ed
by the intersection of the top and sides of the
furnace may be in contact with combustible material.
Failure to maintain proper clearances to
combustible materials can cause a fire,
which could result in damage, death or personal injury.
NOTE: This furnace must be installed so the
electrical components are protected from
water.
Installations on Combustible Flooring
This furnace may not be installed directly on combustible materials in the downflow position. It may be
installed directly on floors made of concrete or othernon-combustible m aterials . If it is nec ess ary to install
the furnace in the do wnflow position on a c ombustible floor, it is req uired that a combustible su b-base
be used. The part number of the correct sub-base
accessory is shown in the specification table on
Page 2
COMBUSTION AND VENTILATION AIR
Provide ventilation and combustion air in accordance with section 5.3, Air for Combustion and
Ventilation, of the NATIONAL FUEL GAS CODE,
ANSI Z223.1, or applicable provisions of the local
building codes. In Canad a, refer to the lat est edition
of the CAN/CGA-B149 Installation Code and local
codes for specifics.
Adequate ventilation and combustion air
must be provided to insure s atisfactory and
safe operation of the furnace. Air openings
in front panel and top panel must not be obstructed. Failure to observe this re commendation could result in asphyxiation.
Do not install the furnace on its back. Doing
so could cause a fire, resulting in damage,
injury or death.
Provide sufficient space around and in front of
the furnace for service and cleaning. Allow a
minimum of 24 inches from the fr ont of the furnace for service clear ance. If the furnace is to
be installed in a close clearance closet, the
door should be of adequate size to allow for
removal of the furnace s hou ld it b ecome necessary.
6
Do not store or use halogen-emitting substances in the vicinity of this appliance.
Such substances include chlorine based
cleaners and swimming pool chemicals, water softening chemicals, de-icing salts and
chemicals, cleaning solvents such as carbon tetrachloride or perchloroethylene,
halogen type refrigerants, printing inks,
paint and paint removers, varnishes, hydrochloric acid, cements and glues, and masonry acid washing materials. The air used
by the burner for combustion must be free
of halogens to avoid possible corrosion to
the heating surfaces, which could result in
asphyxiation.
This furnace is not to be used as a constr uction
heater to supply heat to an unfinished building
during the finishing phas es of co nstruc tion. Th is
practice exposes the furnace to abnormally low
return air temperatures, which can cause condensation in the furnac e or vent leading to premature failure. This practice also exposes the
furnace to an abnormal ly corrosive atmosph ere
from sources such as paint, var nish and adhesives, which can lead to premature heat exchanger or vent failure. The prac tic e also allows
foreign materials such as sawdust or shee t rock
dust to enter the furnace blower, burner, heat
exchanger, motors, and vent system resulting in
shorter life of the fur nace. Use of th is furnace
as a construction heater will void the warranty.
Installations in a Confined Space
A confined space is defined as a space whose
volume is less tha n 50 cubic feet per 1000 BTUH of
the total input ratings of all appliances installed in
the space. If the furnace is to be installed in a
confined space such as a small closet or room,
provisions must be made for supplying combustion
and ventilation air to the space surrounding the
furnace. (See Figure 6) . T his a ir must come from the
outside or from some larger area in the building
which meets the requirements of an unconfined
space.
Two openings of equa l area must be provided; one
starting within twelve inches of the ceiling and one
starting within twelve inches of the floor of the
confined space. The upper o pening must alwa ys be
above the top of the furnace casing. The lower
opening, if in the sidewall, floor or door, shall be
located below the level of the burner in the furnace.
Installations in an Unconfined Space
An unconfined space is defined as a space whose
volume is more than 50 c u bic f eet per 1000 BTUH of
the total input ratings of all appliances installed in
the space. In unconfined spaces in a building of
conventional fram e, masonry, or metal construction,
infiltration is normally adequate to provide air for
combustion and ventilation.
In buildings of tight construction, all air must be
obtained from outdoors or from spaces communicating freely with o utdoors. A permanent o pening or
openings having a total free area of not less than
one square inch for each 5000 BTUH of furnace
input must be provided.
If the furnace is to be installed in a commercial
building, a building with an indoor pool, a laundry
room, hobby or craft room, or c hem ical s tor age area,
all air must be brought in f rom outside as describ ed
above.
Further details on suppl ying outdoor air for combustion may be obtained from Section 5.3.3 of the
National Fuel Gas Code ANSI Z223.1. In Canada,
refer to the latest edition of the CAN/CGA-B149
Installation Code and local codes for specifics.
When the furnace is installed in an attic or
other insulated space, make sure that all in-
sulation is at least 12” away from furnace
combustion air openings. Failure to do this
could cause asphyxiation or fire.
If all air is from inside building, the total free area of
each opening m ust be at least one square inch f or
each 1,000 BTUH of f urnace input but not less than
100 square inches.
If all air is from outdoors, when communicating
directly with the outdoors through v ertical ducts, the
total free area of each openin g must be at least one
square inch for each 4,000 BTUH of furnace input.
When communicating directly with the outdoors
through horizontal ducts, the total free area of each
duct must be at least o ne s q uare inc h f or each 2,000
BTUH of furnace input.
When ducts are used, they must be of the same
cross-sectional area as the f ree ar e a of the op eni ngs
to which they connect. The minimum dimension of
rectangular air ducts must not be less than three
inches.
FIGURE 6 – AIR OPENINGS
7
FURNACE SIZING AND DUCT SYSTEM
DESIGN
The duct system must be installed in conformance
with ASHRAE/NFPA 90, Sta ndard for Installation of
Warm Air Heating and Air Systems and other
applicable local codes. Failure to adhere to proper
duct system design standards can reduce airflow,
resulting in reduced system performance and
possible furnace damage.
Consideration should be given to the heating
capacity require d and also to the air quantity (CFM)
required if A/C is to be installed along with the
furnace or at some future time. These factors can be
determined by calculating the heat loss and heat
gain of the home or structure.
If these calculations are not performed and the
furnace is oversized, the following may result:
1. Short cycling of the furnace.
2. Wide temperature fluctuations f rom the thermostat setting.
3. Reduced overall operating efficiency of the
furnace.
The supply and return duct system must be of
adequate size and designed such that the furnace
will operate within the design ed air temperature ris e
range and not exceed the maximum des igned static
pressure. These values are listed in the table below.
INPUT BTUH
50,000
75,000
100,000
125,000
Additional information, values and data necessary
for heat loss, heat ga in and duc t system design m a y
be found in the ASHR AE HANDBOOK OF FUNDAMENTALS or in other nationally rec ognized public ations recognized by municipal, state, provincial and
federal code authorities.
If possible, it is recommended that the supply air
duct attached to the furnace be provided with a
removable access panel. The opening should be
accessible when the furnace is installed in service
and should be large enough that smoke or ref lected
light may be observed inside the casing to indicate
the presence of leaks in the heat exchanger. The
cover panel for this opening should be attached in
such a manner as to prevent leaks.
A/C Usage Duct Systems
1. When a single (common) duct system is used,
one of the following methods shall be used:
a. A plenum type cooling c oil must be i nstalled
on the air discharge side, or
EXT. STATIC IN. W.C.
MINIMUM MAXIMUM
.10
.12
.15
.20
.50
.50
.50
.50
b. A blower-coil type cooling coil must be in-
stalled in parallel with and isolate d from the
furnace, or
c. A self-contained A/C unit m ust be in par allel
with and isolated from the furnace.
Dampers must be installed when coil-blower
or self-contained unit is employed to prevent conditioned cool air from coming in
contact with the heat exchanger to avoid
moisture condensation and rust-out. This
can allow products of combustion to be circulated into the living area by the furnace
blower resulting in possible asphyxiation. If
dampers are of a manually operated type, a
means must be provided to prevent either
the furnace or A/C unit from operating unless dampers are in full heat or cool position.
If two duct systems are used as could be the case
with a coil-blower or a self-contained A/C unit, the
furnace and A/C unit should be controlled by a
single combination heating and cooling thermostat
which will prevent the furnace and A/C unit from
operating simultaneously.
If a separate heating and separate cooling
thermostat is used, a manually operated
electrical interlock switch must be installed
to prevent simultaneous operation of both
systems and to avoid a possible hazardous
condition due to overheating of the conditioned space.
RETURN AIR AND FILTERS
Return Air Temperature
This furnace design is to be operated in normal
household temperatures. The continuous return air
temperature must not be below 60°F or above 85°F.
Return Air Connection – Upflow
The return air ma y be brought in thr ough the bot tom
of the furnace or through one or both sides of the
furnace casing. The f urnace casing may be c ut out
so that side return air connections may be used. T he
furnace is supplied with flanges on the top of the
furnace to which the return air duct may be fastened.
The casing top is embossed to indicate where to
bend the flanges. If a side return is to be used, cut
out the side of the casing 14 " high by 16 1/4" wide
using the lances in the casing side as a guide. DO
NOT CUT THE OPENING LARGER THAN 14"x 16
1/4". It is not perm issible to cut out the back of the
furnace.
8
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