5565606-TIM-B-1018
32
Johnson Controls Ducted Systems
Figure 26: Bottom Entry Gas Piping
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 specifying 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 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 TempMaster
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.
4.
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.
5.
The gas supply should be a separate line and installed in
accordance with all safety codes as prescribed under
“Limitations”.
OPTIONAL
COIL
GUARD
SHOWN
Table 12: Gas Pipe Sizing - Capacity of Pipe
Length of
Pipe (ft.)
Nominal Iron Pipe Size
3/4 in.
1 in.
1-1/4 in.
10
278
520
1050
20
190
350
730
30
152
285
590
40
130
245
500
50
115
215
440
60
105
195
400
70
96
180
370
80
90
170
350
90
84
160
320
100
79
150
305
Table 13: Gas Heat Minimum Supply Air
Size
(Tons)
Model
Heat Size
Supply Air (CFM)
Cooling
Heating
Min
Max
Min
Max
T06
(6.5)
ZW
(N,S)12
1950
3250
1950
3250
(N,S)18
1950
3250
1950
3250
T07
(7.5)
ZW
(N,S)12
2250
3750
2250
3750
(N,S)18
2250
3750
2250
3750
T08
(8.5)
ZW
(N,S)12
2550
4250
2550
4250
(N,S)18
2550
4250
2550
4250
T10
(10)
ZW
(N,S)18
3000
5000
3000
5000
(N,S)24
3000
5000
3000
5000
T12
(12.5)
ZW
(N,S)18
3750
6250
3750
6250
(N,S)24
3750
6250
3750
6250
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.
