Specifications
9
INSTALLATION
Gas Piping
(See "Gas Piping" diagram on page 15.)
CAUTION:
Gas pressure to humidifier controls must never
exceed 14” W.C. (1/2 psi). A 1/8" inch NPT plugged
tapping, accessible for test gauge connection, must
be installed immediately upstream of the gas supply
connection to the appliance.
• Piping installation must be in accordance with local
codes, and ANSI Z233.1, “National Fuel Gas Code,” or
CAN/CGA-B149 in Canada. Do not use flexible connec-
tors.
• Piping to units should conform with local and national
requirements for type and volume and gas handled, and
pressure drop allowed in the line. Refer to table 9-1 and
9-2 to determine the cubic feet per hour (cfh) for the
type of gas and size of unit to be installed. Using this
value and the length of pipe necessary, determine the
pipe diameter. Where several units are served by the
same main, the total capacity, gas flow (cfh), and length
of main must be considered. Avoid pipe sizes smaller
than 1/2”. Table 9-1 allows for the usual number of
fittings with a 0.3” W.C. pressure drop.
• After threading and reaming the ends, inspect piping
and remove loose dirt and chips.
• Support piping so that no strains are imposed on unit
or controls.
• Use two wrenches when connecting piping to unit
controls.
• Provide a drip pocket before each unit and in the line
where low spots cannot be avoided.
• Take-off to unit should come from top or
side of main to avoid trapping conden-
sate.
• Piping subject to wide temperature
variations should be insulated.
• Pitch piping up toward unit at least
1/4” per 15’ of horizontal run.
• Compounds used on threaded joints of
gas piping must be resistant to the
harmful action of liquefied petroleum
gases.
• Purge air before lighting unit by
disconnecting piping at gas control. In
no case should line be purged into
heat exchanger.
• After installation, check field piping
and humidifier gas train for gas leaks.
• Do not use soap solution, or open flame on humidifier
gas train. A gas leak detector is recommended.
• Install a ground joint union and a manual shut-off valve
immediately upstream of the unit including a 1/8” NPT
plugged tapping accessible for test gauge connection.
Plugged tappings for test gauges are located on all gas
valves.
• Allow at least 5 feet of piping between any high
pressure regulator and unit pipe connection.
Gas Leak Testing
• When leak testing the gas supply piping system, the
humidifier and its gas shut-off valve must be disconnected
during any pressure testing in excess of 14” W.C. (½ psi).
The humidifier must be isolated from the gas supply piping
system by closing its field-installed manual shut-off valve
during any pressure testing equal to or greater than 14"
W.C. (½ psi).
• Check gas supply pressure with all burners running at
inlet pressure tap of combination gas control. (See page
33) The recommended supply pressure should be 7"
W.C. on natural gas or 11" W.C. on LP gas. Purging of
gas piping should be performed as described in ANSI
Z223.1 (latest edition) or, in Canada, in CAN/CGA-B149
codes.
• Minimum supply pressure. Natural - 4½" W.C.
LP - 10" W.C.
• Single stage gas valves GTS™-300, 150, and 75 outlet
pressure (manifold) should be factory set at 3 1/2" w.c. for
natural, 9" w.c. for L.P. This pressure can be checked on
the combination gas valve at the out pressure tap (see
page 33).
Length
of Pipe
Feet
Gas Flow in Piping (Cu. Ft. per Hr.)
(At pressure drop of 0.3 in. water.
Specific gravity = 0.60)
Iron Pipe Size (NPT) Inches
1/2 3/4 1 1-1/4 1-1/2
10 132 278 520 1050 1600
20 92 190 350 730 1100
30 73 152 285 590 890
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
Table 9-2: Specific
Gravity Conversion
Factors
Multiplying factor to be used
with table 9-1 when the
specific gravity of gas is other
than 0.60.
Natural Gas
Specific
Gravity
Factor
0.55 1.04
0.60 1.00
0.65 0.962
Propane Gas
Specific
Gravity
Factor
1.50 0.633
1.53 0.626
1.60 0.612
Table 9-1: Gas Pipe Capacities for Gas
Pressures of .5 PSIG or Less
GTS-IOM-1298.pdf 9 11/17/2009 3:57:03 PM