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5565604-BIM-B-1018
Figure 26: Bottom Entry Gas Piping
Table 13: Gas Heat Minimum Supply Air
Size
Model
(Tons)
-06
ZW
(6.5)
-07
ZW
(7.5)
-08
ZW
(8.5)
-10
ZW
(10)
-12
ZW
(12.5)
Gas Connection
The gas supply line can be routed within the space and roof curb,
exiting through the unit's basepan. Refer to Figures 8 and 9 for
the gas piping inlet location. Typical supply piping arrangements
are shown in Figures 25 and 26. All pipe nipples, fittings, and the
gas cock are field supplied or may be purchased in Ducted
Systems accessory kit #1GP0405.
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.
32
Table 12: Gas Pipe Sizing - Capacity of Pipe
OPTIONAL
COIL
GUARD
SHOWN
NOTE: Maximum capacity of pipe in cubic feet of gas per hour
NOTE: There may be a local gas utility requirement specifying a
Heat Size
Min
N12
1950
N18
1950
N12
2250
N18
2250
N12
2550
N18
2550
N18
3000
N24
3000
N18
3750
N24
3750
4.
5.
Nominal Iron Pipe Size
Length of
Pipe (ft.)
3/4 in.
10
278
20
190
30
152
40
130
50
115
60
105
70
96
80
90
90
84
100
79
based upon a pressure drop of 0.3 inch W.C. and 0.6
specific gravity gas.
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.
Supply Air (CFM)
Cooling
Max
Min
3250
1950
3250
1950
3750
2250
3750
2250
4250
2550
4250
2550
5000
3000
5000
3000
6250
3750
6250
3750
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 compounds such as Gaskolac
or Stalastic, and compounds such as Rectorseal #5,
Clydes's or John Crane may be used.
All piping should be cleaned of dirt and scale by
hammering 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.
The gas supply should be a separate line and installed in
accordance with all safety codes as prescribed under
"Limitations".
Johnson Controls Ducted Systems
1 in.
1-1/4 in.
520
1050
350
730
285
590
245
500
215
440
195
400
180
370
170
350
160
320
150
305
Heating
Max
3250
3250
3750
3750
4250
4250
5000
5000
6250
6250
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