65
JOHNSON CONTROLS
FORM 100.50-EG12 (918)
SMOKE PURGE SEQUENCES
General
The controls of the Series 100 are designed as standard with a ventilation override se-
quence to remove, exhaust, or ventilate smoke, fumes, or other airborne contaminates
from the occupied space. This feature offers three selectable operations: purge, pressur-
ization, and evacuation. The sequence is activated via one of three binary inputs. Some
typical contact closures are smoke detectors, fire alarms, manual switches, etc.
Note:
All cooling and heating modes are disabled during smoke purge.
Purge
–
Purge shall be used to displace the air inside the space with fresh outside air.
When this sequence is started, the following will occur:
Start the supply fan if not already on. (
Note:
With VAV and FlexSys
™
units, the fan speed
will be controlled to maintain the active duct pressure setpoint.) Start the return fan if not
already on. Start the exhaust fan if not already on, and set the VFD to 100%. Set the OA
damper position to 100%. Set the exhaust damper to 100%.
Pressurization
–
Pressurization shall be used to pressurize the building or space in
order to force the air inside the space through the walls to adjacent spaces or outside
the building envelope. When this sequence is started, the following will occur:
Start the supply fan if not already on. (
Note:
With VAV and FlexSys units, the fan speed
shall be controlled to maintain the active duct pressure setpoint.) Stop the return fan if on.
Stop the exhaust fan if on, and set exhaust/return fan VFD to 0%. Set the OA damper to
100%. Set the exhaust damper to 0%.
Evacuation
–
Evacuation shall be used to evacuate (negatively pressurize) the building
or space in order to draw air through the walls from adjacent spaces or outside the
building envelope. When this sequence is started, the following shall occur:
Stop the supply fan if on. Start the return fan if not already on. Start the exhaust fan if not
already on, and set the exhaust/return fan VFD to 100%. Set the OA damper to 0%. Set
the exhaust damper to 100%.
SPECIFIC SEQUENCES
(See the Installation, Operation, and Maintenance manual (100.50-NOM9) for further detail.)
Variable Air Volume (VAV) Mode
Occupied Cooling –
In the occupied cooling mode, the unit controller monitors the RAT
and compares it to the RAT cooling setpoint. The RAT cooling setpoint is entered into the
unit controller through the setpoint key, cooling subsection of the user interface. If the RAT
is equal to or greater than the RAT cooling setpoint plus 0.5°F, the unit controller will place
the unit in the occupied cooling mode. The unit will remain in the occupied cooling mode
until the RAT is equal to or less than the RAT cooling setpoint minus 0.5°F.
Occupied Heating –
In the occupied heating mode, the unit controller monitors the RAT
and compares it to the RAT heating setpoint. The RAT heating setpoint is entered into the
unit controller through the set points key heating subsection of the user interface. If the
RAT is equal to or less than the RAT heating setpoint minus 0.5°F, the unit controller will
place the unit in the occupied heating mode. The unit will remain in the occupied heating
mode until the RAT is equal to or greater than the RAT heating setpoint plus 0.5°F.