JOHNSON CONTROLS
103
SECTION 5 – SEQUENCE OF OPERATION
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
5
LD14363
FIGURE 54 - RETURN FAN ASSEMBLY
• The return fan assembly always has a return fan
VFD.
• A return fan assembly is ON whenever the supply
fan assembly is ON.
• A return fan assembly has one VFD and two motor/
blower assemblies. See Figure 54 on page 103.
• Exhaust fan assembly options are:
1. ON/OFF control based on outside air damper
position (SZVAV only)
2. ON/OFF control based on building pressure
3. Modulating damper with single speed ex-
haust fan
4. Modulating exhaust fan with barometric
damper
5. If the Series 100 unit was ordered as mod-
ulating damper - VFD, the exhaust fan can
also be controlled from the BAS.
• Return fan assembly options are:
1. Return fan without exhaust
2. Return fan with exhaust
Exhaust Fan Assembly
• The exhaust fan assembly in the Series 100 unit is
used to control building static pressure.
• The exhaust fan assembly can be ordered as one
of four options.
• The exhaust fan assembly only operates with a
demand from the building pressure setpoint or the
position of the outside air damper.
Exhaust Fan Assembly Setup
• Power exhaust type must be set in the OPTIONS-
EXHAUST menu.
• Building pressure setpoint must be set in the SET-
POINTS-EXHAUST menu.
• Other setpoints specic to the power exhaust type
must be set in the SETPOINTS-EXHAUST menu.
ON/OFF Damper Control Sequence of
Operation
• Power exhaust type must be set to ON-OFF
Damper Control in the OPTIONS-EXHAUST
menu.
• Building pressure setpoint must be set in the SET-
POINTS-EXHAUST menu.
• Economizer output for fan start must be set in the
SETPOINTS-EXHAUST menu.
• Econo output for fan stop must be set in the SET-
POINTS-EXHAUST menu.
• This control sequence uses a single speed exhaust
fan with a barometric damper.
• When the position of the outside air damper is
greater than the economizer output for fan start,
the exhaust fan is turned ON.
• When the position of the outside air damper is less
than the economizer output for fan stop, the ex-
haust fan is turned OFF.
ON/OFF Building Pressure Control Sequence
of Operation
• Power exhaust type must be set to ON-OFF Pres-
sure Control in the OPTIONS-EXHAUST menu.
• Building pressure setpoint must be set in the SET-
POINTS-EXHAUST menu.
• Building pressure control offset must be set in the
SETPOINTS-EXHAUST menu.
• This control sequence uses a single speed exhaust
fan with a barometric damper. When the current
building pressure is greater than the building pres-
sure setpoint plus the building pressure control
offset, the exhaust fan is turned ON.
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