156
JOHNSON CONTROLS
5276178-JIM-C-0118
Sequence of Operation
DAMPER can be configured for:
•
Demand Ventilation
•
Fixed Minimum
In order for the Ventilation System to be active the
following must occur:
•
The unit mode must be OCC STANDBY, OCC
COOLING, OCC COOLING LOW, OCC
COOLING HIGH, OCC HEATING, OCC
HEATING LOW, OCC HEATING HIGH, OCC
COOLING WITH BYPASS, or OCC COOLING
WITHOUT BYPASS.
•
There must be a 24V output from the Unit Con-
troller to the Supply Fan control circuit. This out-
put is contained at Terminal Block TB1-Terminal
2.
•
There must be a 24V input to the Unit Controller
from the Supply Fan Air Proving Switch to verify
Supply Fan operation 30 seconds after the Supply
Fan circuit is energized. This input is contained
at Terminal Block TB7 – Terminal 10.
•
When the economizer becomes active the
position of the dampers are controlled by the
Economizer PI logic and can move the dampers
beyond the Active Ventilation Minimum Posi-
tion; however, the Economizer PI logic can never
close the dampers less than the Active Ventilation
Minimum Position.
2-Position Damper
Required Program Values
“ D A M P E R H A R D WA R E ”
must be set to
“2-POSITION”.
This is set through the OPTIONS key,
VENTILATION subsection of the User Interface.
“VENTILATION SYSTEM”
must be set to USER
ENABLED. This is set through the PROGRAM key,
VENTILATION subsection of the User Interface.
In order to use the Demand Ventilation feature, a CO
2
sensor (part number 025-36461-000) must be installed
in the return air and be connected to terminal 11 (IAQ
ID+) and terminal 12 (IAQ ID-) of the CTB3 terminal
block. Another sensor must be installed in the outdoor
air and be connected to terminal 13 (IAQ OD+) and
Terminal 14 (IAQ OD-) of the CTB3 terminal block.
Sequence of Operation
The analog output to the Outdoor damper is 10.0V
when the Ventilation System Status is active. The
analog output to the Outdoor damper is 0.0V when the
Ventilation System Status is inactive. The amount of
outdoor air is set by adjusting the damper linkage.
Demand Ventilation
In order to use the Demand Ventilation feature, a CO
2
sensor (part number 025-36461-000) must be installed
in the return air and be connected to terminal 11 (IAQ
ID+) and terminal 12 (IAQ ID-) of the CTB3 terminal
block. Another sensor must be installed in the outdoor
air and be connected to terminal 13 (IAQ OD+) and
Terminal 14 (IAQ OD-) of the CTB3 terminal block.
Required Program Values
“VENTILATION CONTROL”
must be set to
“DEMAND”
. This is set through the OPTIONS key,
VENTILATION subsection of the User Interface.
“DAMPER HARDWARE”
must be set to
“STANDARD
DAMPERS”.
This is set through the OPTIONS key,
VENTILATION subsection of the User Interface.
“VENTILATION SYSTEM”
must be set to USER
ENABLED. This is set through the PROGRAM key,
VENTILATION subsection of the User Interface.
“CO
2
OFFSET SETPOINT”
must be set through the
SETPOINTS key, VENTILATION subsection of the
User Interface.
On units configured as
“STANDARD DAMPERS”
the
“OA DAMPER MINIMUM POSITION”
and
“OA
DAMPER MAXIMUM POSITION”
must be set through
the SETPOINTS key, VENTILATION subsection of
the User Interface.
Sequence of Operation
The position of the outdoor air damper is determined by
the difference of the CO
2
level in the return air versus the
CO
2
level of the outdoor air. When the indoor CO
2
level
becomes more than or equal to the outdoor CO
2
level
plus the
“CO
2
OFFSET SETPOINT”
the Unit Controller
will use a PI algorithm to open the outside air damper
from the
“OA DAMPER MINIMUM POSITION”
towards the
“OA DAMPER MAXIMUM POSITION”
setting. The Unit Controller will then modulate the
damper to lower the indoor CO
2
level between the
minimum and maximum settings.
The indoor C0
2
level can be either hard wired or
communicated. In order to communicate the indoor C0
2
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