GC9C96 Service Manual

SYSTEM OPERATION
9
amount of air into the burner. This may cause incomplete
combustion, ashback, and possible yellow tipping.
In some areas the gas supplier may articially derate the gas
in an e󰀨ort to compensate for the e󰀨ects of altitude. If the
gas is articially derated, the appropriate orice size must be
determined based upon the BTU/ft
3
content of the derated
gas and the altitude. Refer to the National Fuel Gas Code,
NFPA 54/ANSI Z223.1, and information provided by the gas
supplier to determine the proper orice size.
A di󰀨erent pressure switch may be required at high altitude
regardless of the BTU/ft
3
content of the fuel used. Refer to the
product Specication Sheet for a tabular listing of appropriate
altitude ranges and corresponding manufacturer’s pressure
switch kits.



B RRT G R JR R T  R 
T RRT R KT R T T
T
 RRT KT
T B  T R   RR R RT


R T B RR B  Q TR R R
G
This unit is configured for natural gas. The appropriate
manufacturer’s propane gas conversion kit, must be applied
for propane gas installations.
Refer to the specification sheet for the model you are
servicing. Refer to the “propane gas and/or High Altitude
Installations” section for details.

This unit is equipped with a 24 volt gas valve controlled
during furnace operation by the integrated control module.
As shipped, the valve is congured for natural gas. The valve
is eld convertible for use with propane gas by using the
appropriate propane gas conversion kit. Taps for measuring
the gas supply pressure and manifold pressure are provided
on the valve.
NOTE: The gas supply pressure on White-Rodgers “G/J”
model gas valve, can be checked with a gas pressure test
kit (Part #0151K00000S) available through our authorized
distributors.
The gas valve has a manual ON/OFF control located on
the valve itself. This control may be set only to the “ON” or
“OFF” position. Refer to the Lighting Instructions Label or the
“Putting the Furnace Into Operation” section of this manual or
the installation instructions for use of this control during start
up and shut down periods.


T
  B TTR RT
 R QT
G
 T RRG  QT  T RR  
TRR G G   RG  R T
TRTK T T R
The gas piping supplying the furnace must be properly sized
based on the gas ow required, specic gravity of the gas,
and length of the run. The gas line installation must comply
with local codes, or in their absence, with the latest edition of
the National Fuel Gas Code, NFPA 54/ANSI Z223.1.
Length of
Nominal Black Pipe Size
Pipe in Feet
1/2"
3/4"
1"
1 1/4"
1 1/2"

132
278
520
1050
1600

92
190
350
730
1100

73
152
285
590
980

63
130
245
500
760

56
115
215
440
670

50
105
195
400
610

46
96
180
370
560

43
90
170
350
530

40
84
160
320
490

38
79
150
305
460
CFH =
(Pressure 0.5 psig or less and pressure drop of 0.3" W.C.; Based on 0.60 Specific
Gravity Gas)
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
BTUH Furnace Input
Heating Value of Gas (BTU/Cubic Foot)
To connect the furnace to the building’s gas piping, the installer
must supply a ground joint union, drip leg, manual shuto󰀨
valve, and line and ttings to connect to gas valve. In some
cases, the installer may also need to supply a transition piece
from 1/2” pipe to a larger pipe size.
The following stipulations apply when connecting gas piping.
Refer to the following gures for typical gas line connections
to the furnace.
1. Use black iron or steel pipe and ttings for the building
piping.
2. Use pipe joint compound on male threads only. Pipe
joint compound must be resistant to the action of the
fuel used.
3. Use ground joint unions.
4. Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum of
three inches long.
5. Install a 1/8” NPT pipe plug tting, accessible for test
gage connection, immediately upstream of the gas
supply connection to the furnace.
6. Use two pipe wrenches when making connection to
the gas valve to keep it from turning. The orientation of
the gas valve on the manifold must be maintained as
shipped from the factory.
7. Install a manual shuto󰀨 valve between the gas meter
and unit within six feet of the unit. If a union is installed,
the union must be downstream of the manual shuto󰀨
valve, between the shuto󰀨 valve and the furnace.
8. Tighten all joints securely.