Carrier WeatherExpert 48N2 Installation Instructions Manual page 47

PRESSURIZATION — Pressurization mode is intended to
keep smoke out of a zone. The factory-installed optional
economizer is required for this function. Pressurization is ac-
complished by the following:
• opening the economizer (option)
• running the supply fan (optional inlet guide vanes open or
optional VFD at normal duct static pressure set point)
• closing the power exhaust dampers (if installed as option or
accessory)
• shutting off the power exhaust fans (if installed as option or
accessory)
This allows the space to be overpressurized relative to adjacent
zones and prevents or slows entry of smoke into this space
from adjacent zones. See Fig. 58 for wiring.
EVACUATION — Evacuation mode removes smoke or un-
desirable air from interior spaces without reintroducing unsuit-
able air. The factory-installed optional economizer with option/
accessory power exhaust is required for this function. Evacua-
tion is accomplished by the following:
• turning the supply fan off
• opening the economizer (option required)
• running the exhaust fans (option or accessory required)
• opening the exhaust dampers.
See Fig. 58 for wiring.
SMOKE PURGE — Smoke Purge mode removes smoke from
the interior spaces and replaces it with fresh outside air. The
factory-installed optional economizer with option/accessory
power exhaust are required for this function. Smoke purge is
accomplished by the following:
• turning supply fan on
• opening the economizer (option required)
• running the exhaust fans (option or accessory required)
• opening the exhaust dampers
See Fig. 58 for wiring.
SMOKE CONTROL INSTALLATION — Implementa-
tion of the various smoke control modes on these units re-
quires the installer to modify the unit wiring to add con-
tacts (via either manual switches or relays) that will selec-
tively interrupt and override standard factory control
sequences. See Table 16 and Fig. 56 and 57 and the Con-
trols, Start-Up, Operation, Service and Troubleshooting
manual for more information.
Table 16 — Smoke Control Modes
FUNCTION
Fire
Shutdown
Supply Fan Off
VFD† —
Economizer Closed
Return Air
Open
Damper
Exhaust
Off
Fans
Exhaust
Closed
Damper
LEGEND
VAV — Variable Air Volume
VFD — Variable Frequency Drive
*Power exhaust option required for this mode.
†Applicable to VAV units with appropriate options.
47
MODE
Pressur- Smoke
Evacuation*
ization Purge*
On Off On
Open/On — Open/On
Open Open Open
Closed Closed Closed
Off On On
Closed Open Open