Gas Pipe Sizing - Capacity Of Pipe; Gas Heat Minimum Supply Air; Bottom Entry Gas Piping - York ZR Series Installation Manual

Figure 26: Bottom entry gas piping
Table 15: Gas heat minimum supply air
Size (tons) Model
078
ZR
(6.5)
090
ZR
(7.5)
102
ZR
(8.5)
120
ZR
(10)
150
ZR
(12.5)
Gas connection
Route the gas supply line within the space and roof curb with the
exit through the unit's basepan. See 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 the Ducted
Systems accessory kit #1GP0405.
Apply the following gas piping recommendations.
• You must install a drip leg and a ground joint union in the
gas piping.
• When required by local codes, install a manual shut-off
valve outside of the unit.
• Use wrought iron or steel pipe for all gas lines. Apply pipe
dope sparingly to male threads only.
Johnson Controls Ducted Systems
Table 14: 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
Minimum
N12 1950
N18 1950
N12 2250
N18 2250
N12 2550
N18 2550
N18 3000
N24 3000
N18 3750
N24 3750
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. The line
must not be sized smaller than the entrance fitting size.
Supply air (CFM)
Cooling
Maximum Minimum
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.
• Clean all piping of dirt and scale. Hammer on the outside
of the pipe and blow out loose particles. Before initial
start-up, make sure that all gas lines external to the unit
are purged of air.
• The gas supply must be a separate line and installed in
accordance with all safety codes as prescribed under
Limitations.
5167531-YIM-J-1019
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
Maximum
3250
3250
3750
3750
4250
4250
5000
5000
6250
6250
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