6021980-UIM-A-1120
Johnson Controls Ducted Systems 35
Optional electric heat
The factory-installed heaters are wired for single point power
supply. You only need to bring the power supply into the single
point terminal block.
These CSA approved heaters are located within the central
compartment of the unit with the heater elements extending in
to the supply air chamber.
Fuses are supplied, where required, by the factory. Some kW
sizes require fuses and others do not. See Table 14 for
minimum CFM limitations.See Table 12 for electrical data.
Optional gas heat
The optional 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.
Follow the “National Fuel Gas Code” Z223.1 (in U.S.A.) or the
current Gas Installation Codes CSA-B149.1 (in Canada) in all
cases unless they are superseded by local codes or gas utility
requirements.
See Table 15, Gas pipe sizing - capacity of pipe, on page 36.
The heating value of the gas may vary by locality. You must
check the value with the local gas utility.
Figure 22: Side entry gas piping
Table 14: Electric heat minimum supply air
Size (tons) Model Voltage
Minimum supply air (CFM)
Heater kW
918243654
078
(6.5)
ZT
208/230-3-60 1950 1950 1950 1950 -
460-3-60 1950 1950 1950 1950 -
090
(7.5)
ZT
208/230-3-60 1950 1950 1950 1950 -
460-3-60 2250 2250 2250 2250 -
102
(8.5)
ZT
208/230-3-60 2550 2550 2550 2550 -
460-3-60 2550 2550 2550 2550 -
120
(10)
ZT
208/230-3-60 - 3000 3000 3000 3500
460-3-60 - 3000 3000 3000 3000
150
(12.5)
ZT
208/230-3-60 - 3750 3750 3750 4000
460-3-60 - 3750 3750 3750 3750
OPTIONAL
COIL
GUARD
SHOWN
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