5326602-XIM-B-1019
Johnson Controls Ducted Systems
25
Optional Gas Heat
These gas-fired heaters have aluminized-steel or optional
stainless steel, tubular heat exchangers with spark ignition.
Gas Piping
Proper sizing of gas piping depends on the cubic feet per hour
of gas flow required, specific gravity of the gas and the length of
run. "National Fuel Gas Code" Z223.1 (in U.S.A.) or the current
Gas Installation Codes CSA-B149.1 (in Canada) should be
followed in all cases unless superseded by local codes or gas
utility requirements. Refer to the Pipe Sizing Table 20. The
heating value of the gas may differ with locality. The value
should be checked with the local gas utility.
Figure 25: Side Entry Gas Piping
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.
OPTIONAL
COIL
GUARD
SHOWN
OPTIONAL
COIL
GUARD
SHOWN
Table 17: Gas Heat Minimum Supply Air Imperial
Size
(Ton)
Model
Heat
Size
Supply Air (CFM)
Cooling
Heating
Min
Max
Min
Max
120
(10)
ZF
N18
3000
5000
3000
5000
N24
3000
5000
3000
5000
150
(12.5)
ZF
N18
3750
6250
3750
6250
N24
3750
6250
3750
6250
Table 18: Gas Heat Minimum Supply Air Metric
Size
(KW)
Model
Heat
Size
Supply Air (M
3
S)
Cooling
Heating
Min
Max
Min
Max
120
(35)
ZF
N18
1.42
2.36
1.42
2.36
N24
1.42
2.36
1.42
2.36
150
(44)
ZF
N18
1.76
2.95
1.76
2.95
N24
1.76
2.95
1.76
2.95
