127408-YIM-B-0606
22
Unitary Products Group
NOTE:
Maximum capacity of pipe in cubic feet of gas per
hour based upon a pressure drop of 0.3 inch W.C.
and 0.6 specific gravity gas.
NOTE:
There may be a local gas utility requirement specify-
ing a minimum diameter for gas piping. All units
require a 3/4 inch pipe connection at the entrance
fitting. Line should not be sized smaller than the
entrance fitting size.
GAS CONNECTION
The gas supply line can be routed within the space and roof
curb, exiting through the unit’s basepan. Refer to Figure 9 for
the gas piping inlet location. Typical supply piping arrange-
ments are shown in Figures 21 and 22. All pipe nipples, fit-
tings, and the gas cock are field supplied or may be
purchased in UPG accessory kit #1GP0404.
Gas piping recommendations:
1.
A drip leg and a ground joint union must be installed in
the gas piping.
2.
Where required by local codes, a manual shut-off valve
must be installed outside of the unit.
3.
Use wrought iron or steel pipe for all gas lines. Pipe dope
should be applied sparingly to male threads only.
4.
All piping should be cleaned of dirt and scale by ham-
mering on the outside of the pipe and blowing out loose
particles. Before initial start-up, be sure that all gas lines
external to the unit have been purged of air.
5.
The gas supply should be a separate line and installed in
accordance with all safety codes as prescribed under
“Limitations”.
6.
A 1/8-inch (3.175 mm) NPT plugged tapping, accessible
for test gage connection, must be installed immediately
upstream of the gas supply connection to the unit.
7.
After the gas connections have been completed, open
the main shut-off valve admitting
normal gas pressure
to
the mains.
Check all joints for leaks with soap solution or
other material suitable for the purpose.
NEVER USE A
FLAME
.
TABLE 16: GAS PIPE SIZING - CAPACITY OF PIPE
Length of
Pipe ft. (m)
Nominal Iron Pipe Size
3/4 in.
1 in.
1-1/4 in.
10 (3)
278 (7.8)
520 (14.7)
1050 (29.7)
20 (6)
190 (5.3)
350 (9.9)
730 (20.6)
30 (9.1)
152 (4.3)
285 (8)
590 (16.7)
40 (12.1)
130 (3.6)
245 (6.9)
500 (14.1)
50 (15.2)
115 (3.2)
215 (6)
440 (12.4)
60 (18.2)
105 (2.9)
195 (5.5)
400 (12.4)
70 (21.3)
96 (2.7)
180 (5)
370 (10.4)
80 (24.3)
90 (2.5)
170 (4.8)
350 (9.9)
90 (27.4)
84 (2.3)
160 (4.5)
320 (9)
100 (30.4)
79 (2.2)
150 (4.2)
305 (8.6)
Natural gas may contain some propane. Propane is
an excellent solvent and will quickly dissolve white
lead and most standard commercial compounds. A
special pipe dope must be used when assembling
wrought iron or steel pipe. Shellac based com-
pounds such as Gaskolac or Stalastic, and com-
pounds such as Rectorseal #5, Clydes’s or John
Crane may be used.
FIRE OR EXPLOSION HAZARD
Failure to follow the safety warning exactly could
result in serious injury, death or property damage.
Never test for gas leaks with an open flame. Use a
commercially available soap solution made specifi-
cally for the detection of leaks to check all connec-
tions. A fire or explosion may result causing property
damage, personal injury or loss of life.
The furnace and its individual shut-off valve must be
disconnected from the gas supply piping system
during any pressure testing at pressures in excess
of 1/2 PSIG.
Pressures greater than 1/2 PSIG will cause gas
valve damage resulting in a hazardous condition. If it
is subjected to a pressure greater than 1/2 PSIG, the
gas valve must be replaced.
The furnace must be isolated from the gas supply
piping system by closing its individual manual shut-
off valve during any pressure testing of the gas sup-
ply piping system at test pressures equal to or less
than 1/2 PSIG.
Threaded joints should be coated with a sealing
compound that is resistant to the action of liquefied
petroleum gases.
Do not use Teflon tape.
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