JOHNSON CONTROLS
29
SECTION 2 – INSTALLATION
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
2
AIR HOODS FOR FIXED OUTSIDE AIR (UNITS
WITHOUT ECONOMIZER)
These hoods are factory installed. The dampers may be
adjusted by loosening the thumb screw, turning the le-
ver to the desired position, and retightening the thumb
screw.
AIR HOODS FOR EXHAUST AIR
When furnished, these hoods and dampers are factory
installed.
FIELD WIRING
Figure 7 on page 31 and Figure 8 on page 32
show the field control wiring to CTB1. All field control
wiring is field supplied and installed.
Thermostat
A thermostat (2 stage cool or 2 stage heat) can be used
on CV units. On CV units the thermostat is the primary
means of control for the unit. The thermostat should be
mounted on an inside wall approximately 56" above
the floor where it will not be subject to drafts, sun ex-
posure or heat from electrical fixtures or appliances.
Space Sensor
The space sensor (if used) can be used on either CV
or VAV units. The space saver sensor can be used for
unit control in lieu of a thermostat on CV units. For
SZVAV units, only a space sensor can be used. This
can be hardwired or a communicated signal. Even if a
thermostat is wired to the rooftop unit, the space sensor
will supply space air temperature values if connected.
When mounting a space sensor, it should be located on
an inside wall approximately 56 inches above the floor
where it will not be subject to drafts, sun exposure or
heat from electrical fixtures or appliances.
Shielded
Wire must be used that is grounded at control panel
only.
CO
2
Sensor
The optional CO
2
sensor is used for demand ventila-
tion. When ordered a CO
2
sensor is installed in the out-
door and return air stream.
Occupied/Unoccupied Input
A contact-closure input is provided for hard-wiring
an external device such as a central time clock, a ther-
mostat with scheduling or BAS system, or a manual
switch.
Contact Closure = Occupied
Contacts Open = Unoccupied
Note that 24 volts (24 VAC), terminal 1 of the termi-
nal block CTB1, must be used as the 24 VAC source
for switching the contact to the IPU board Occupied/
Unoccupied input. Use of any power source external to
the controller will result in damage to the IPU board.
Shutdown Input
A contact-closure input is provided for emergency
shutdown of the unit. When this circuit is open, the unit
shuts down with supply fan, exhaust fan turned OFF,
and outside air dampers are closed. This state is main-
tained until the input is activated (contacts closed).
• Contact Closed = Normal Operation
• Contacts Open = Shutdown
Note that a jumper is installed at the factory between
terminals 3 (24VAC) and terminal 4 (SD) of the low
voltage terminal block CTBl. When a field shutdown
input is used, the jumper must be removed and the ex-
ternal dry contact connected between terminal 3 and 4.
The connection of an external power supply to these
terminals will result in damage to the IPU board.
Smoke Purge Input
There are three field connection points for smoke
purge operation: smoke purge l, smoke purge 2, and
smoke purge 3.
When a field supplied dry contact is closed between
terminal 3 (24 VAC) and terminal 6 (SMK1), the unit
will initiate whatever smoke purge sequence has been
programmed into the IPU board for smoke purge se-
quence 1.
When a field supplied dry contact is closed between
terminal 3 (24VAC) and terminal 7 (SMK2), the unit
will initiate whatever smoke purge sequence has been
programmed into the IPU board for smoke purge se-
quence 2.
When a field supplied dry contact is closed between
terminal 3 (24VAC) and terminal 8 (SMK3), the unit
will initiate whatever smoke purge sequence has been
programmed into the IPU board for smoke purge se-
quence 3.
Refer to
Smoke Purge section on page 112
for addi-
tional programming information. The smoke purge op-
erating state is maintained until the contact is opened.