GMES96-U Installation Manual

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union must be downstream of the manual shutoff valve,
between the shutoff valve and the furnace.
• Tighten all joints securely.
Natural Gas Capacity of Pipe
In Cubic Feet of Gas Per Hour (CFH)
Length of Nominal Black Pipe Size
Pipe in Feet 1/2" 3/4" 1" 1 1/4" 1 1/2"
10 132 278 520 1050 1600
20 92 190 350 730 1100
30 73 152 285 590 980
40 63 130 245 500 760
50 56 115 215 440 670
60 50 105 195 400 610
70 46 96 180 370 560
80 43 90 170 350 530
90 40 84 160 320 490
100 38 79 150 305 460
(Pressure 0.5 psig or less and pressure drop of 0.3" W.C.; Based on
0.60 Specific Gravity Gas)
CFH =
BTUH Furnace Input
Heating Value of Gas (BTU/Cubic Foot)
Table 6
• Connection method must be in compliance with all local
and national codes. US: National Fuel Gas Code (NFGC)
NFPA 54-2012/ANSI Z223.1-2012 and the Installation
Standards, Warm Air Heating and Air Conditioning
Systems ANSI/NFPA 90B.
Connect the furnace to the building piping by one of the
following methods:
– Rigid metallic pipe and fittings.
– Semi-rigid metallic tubing and metallic fittings.
Aluminum alloy tubing must not be used in exterior
locations. In order to seal the grommet cabinet
penetration, rigid pipe must be used to reach the
outside of the cabinet. A semi-rigid connector to the
gas piping may be used from there.
• Use listed gas appliance connectors in accordance with
their instructions. Connectors must be fully in the same
room as the furnace.
• Protect connectors and semirigid tubing against physical
and thermal damage when installed. Ensure aluminum-
alloy tubing and connectors are coated to protect against
external corrosion when in contact with masonry, plaster,
or insulation, or subjected to repeated wetting by liquids
such as water (except rain water), detergents, or sewage.
The gas piping may enter the left or right side of the furnace
cabinet. The installer must supply following fittings starting
from the gas valve.
• 1/2" dia x 2" long nipple
• 90 degree elbow
• Additional length of rigid piping enough to reach the
outside of the cabinet
• Grounded joint union
• Drip leg
position. Refer to the lighting instructions label or Startup Pro-
cedure & Adjustment for use of this control during start up and
shut down periods.
GAS PIPING CONNECTIONS
T O AVOID POSSIBLE UNSATISFACTORY OPERATION OF EQUIPMENT
DAMAGE DUE TO UNDERFIRING OR EQUIPMENT , USE THE PROPER SIZE
OF NATURAL GAS PIPING NEEDED WHEN RUNNING PIPE FROM THE
METER / TANK TO THE FURNACE .
WARNING
When sizing gas lines, be sure to include all appliances which
will operate simultaneously. The gas piping supplying the fur-
nace 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
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 figures 28 and 29 for typical gas
line connections 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
3" 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