GCSS96 Installation Manual

27
T O AVOID POSSIBLE UNSATISFACTORY OPERATION OF EQUIPMENT
DAMAGE DUE TO UNDERFIRING OR EQUIPMENT , USE THE PROPER SIZE
OF NATURAL / PROPANE GAS PIPING NEEDED WHEN RUNNING PIPE FROM
THE METER / TANK TO THE FURNACE .
WARNING
HIGH ALTITUDE DERATE
When this furnace is installed at high altitude, the appropriate
High Altitude orifice kit must be applied. This is required due to
the natural reduction in the density of both the gas fuel and
combustion air as altitude increases. The kit will provide the
proper design certified input rate within the specified altitude
range.
High altitude kits are purchased according to the installation
altitude and usage of either natural or propane gas. Consult
the furnace Specification Sheet for appropriate kits.
Do not derate the furnace by adjusting the manifold pressure to
a lower pressure than specified on the furnace rating plate. The
combination of the lower air density and a lower manifold pres-
sure will prohibit the burner orifice from drawing the proper
amount of air into the burner. This may cause incomplete com-
bustion, flashback, and possible yellow tipping.
In some areas the gas supplier may artificially derate the gas in
an effort to compensate for the effects of altitude. If the gas is
artificially derated, the appropriate orifice size must be deter-
mined 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 deter-
mine the proper orifice size.
A different pressure switch may be required at high altitude
regardless of the BTU/ft
3
content of the fuel used. Consult the
furnace Specification Sheet for pressure switch.
PROPANE GAS CONVERSION
This unit is configured for natural gas. To operate this furnace
on L.P. gas, an LPM-07 LP Conversion kit must be used.
The indicated kit must be used to insure safe and proper fur-
nace operation. All conversions must be performed by a quali-
fied installer, or service agency.
GAS VALVE
This unit is equipped with a 24 volt gas valve controlled during
furnace operation by the integrated control module. As shipped,
the valve is configured for natural gas. The valve is field con-
vertible for use with propane gas by replacing the regulator spring
with a propane gas spring from an appropriate manufacturer’s
propane gas conversion kit. Taps for measuring the gas supply
pressure and manifold pressure are provided on the valve.
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” posi-
tion. Refer to the lighting instructions label or Startup Proce-
dure & Adjustment for use of this control during start up and
shut down periods.
GAS PIPING CONNECTIONS
The gas piping supplying the furnace must be properly sized based
on the gas flow required, specific 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 or CAN/CSA B149.1-15 in
Canada.
To connect the furnace to the building’s gas piping, the installer
must supply a ground joint union, drip leg, manual shutoff valve,
and line and fittings 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. Re-
fer to Gas Piping Connections figure for typical gas line connec-
tions to the furnace.
• Gas piping must be supported external to the furnace
cabinet so that the weight of the gas line does not
distort the burner rack, manifold or gas valve.
• Use black iron or steel pipe and fittings for building piping.
Where possible, use new pipe that is properly chamfered,
reamed, and free of burrs and chips. If old pipe is used,
be sure it is clean and free of rust, scale, burrs, chips,
and old pipe joint compound.
• Use pipe joint compound on male threads ONLY. Always
use pipe joint compound (pipe dope) that is APPROVED
FOR ALL GASSES. DO NOT apply compound to the first
two threads.
• Use ground joint unions.
• 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.
• Install a 1/8" NPT pipe plug fitting, accessible for test
gauge connection, immediately upstream of the gas supply
connection to the furnace.
• Always use a back-up wrench when making the 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. Maximum torque for the gas
valve connection is 375 in-lbs; excessive over-tightening
may damage the gas valve.
• Install a manual shutoff 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 shutoff valve,
between the shutoff valve and the furnace.
• Tighten all joints securely.