RT-SVX073A-EN
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– Supply Fan - Off
– Supply Fan VFD - Closed/Min (if so equipped)
– Exhaust Fan - Off; Exhaust Dampers Closed (if so
equipped)
– OA Dampers - Closed; Return Damper - Open
– Heat - All heat stages off; Mod Heat output at 0
VDC
– Occupied/Unoccupied/VAV box output - Energized
– VOM Relay - Energized (if so equipped)
– Preheat Output - Off
– Return Fan - Off; Exhaust Dampers - Closed (if so
equipped)
– Return VFD - Min (if so equipped)
• EMERG_FIRE - Input from fire pull box/system
– Supply Fan - Off
– Supply Fan VFD - Closed/Min (if so equipped)
– Exhaust Fan - Off; Exhaust Dampers Closed (if so
equipped)
– OA Dampers - Closed; Return Damper - Open
– Heat - All heat stages off; Mod Heat output at 0
VDC
– Occupied/Unoccupied/VAV box output - Energized
– VOM Relay - Energized (if so equipped)
– Preheat Output - Off
– Return Fan - Off; Exhaust Dampers - Closed (if so
equipped)
– Return VFD - Min (if so equipped)
Ventilation Override Module (VOM)
Important: The ventilation override system should not be
used to signal the presence of smoke caused
by a fire, as it is not intended nor designed to
do so.
The user can customize up to five (5) different override
sequences for purposes of ventilation override control. If
more than one VOM sequence is being requested, the
sequence with the highest priority is initiated first.
Sequence hierarchy is the sequence “A” (UNIT OFF) is
first, with sequence “E” (PURGE with Duct Pressure
Control) last. A ventilation override mode can be initiated
by closing any of the five (5) corresponding binary inputs
on the VOM module. A binary output is provided on the
VOM module to provide remote indication of an active VOM
mode. All compressors, condenser fans and the
Humidification output are deenergized for any VOM
sequence. The factory default definitions for each mode
are as follows:
• UNIT OFF sequence “A”
When complete system shutdown is required the
following sequence can be used.
– Supply Fan - Off
– Supply Fan VFD - Closed/Min (if so equipped)
– Exhaust Fan - Off; Exhaust Dampers Closed (if so
equipped)
– OA Dampers - Closed; Return Damper - Open
– Heat - All heat stages off; Mod Heat output at 0
VDC
– Occupied/Unoccupied/VAV box output -
Deenergized
– VOM Relay - Energized
– Preheat Output - Off
– Return Fan - Off; Exhaust Dampers - Closed (if so
equipped)
– Return VFD - Min (if so equipped)
– OA Bypass Dampers - Open (if so equipped)
– Exhaust Bypass Dampers - Open (if so equipped)
• PRESSURIZE sequence “B”
Perhaps a positively pressurized space is desired
instead of a negatively pressurized space. In this
case, the supply fan should be turned on with VFD
at 100% speed and exhaust fan should be turned
off.
– Supply Fan - On
– Supply Fan VFD - Max (if so equipped)
– Exhaust Fan - Off; Exhaust Dampers Closed (if so
equipped)
– OA Dampers - Open; Return Damper - Closed
– Heat - All heat stages off; Mod Heat output at 0
VDC
– Occupied/Unoccupied/VAV box output - Energized
– VOM Relay - Energized
– Preheat Output - Off
– Return Fan - Off; Exhaust Dampers - Closed (if so
equipped)
– Return VFD - Min (if so equipped)
– OA Bypass Dampers - Open (if so equipped)
– Exhaust Bypass Dampers - Open (if so equipped)
• EXHAUST sequence “C”
With only the exhaust fans running (supply fan off),
the space that is conditioned by the rooftop would
become negatively pressurized. This is desirable
for clearing the area of smoke from the now-
extinguished fire, possibly keeping smoke out of
areas that were not damaged.
– Supply Fan - Off
– Supply Fan VFD - Closed/Min (if so equipped)
– Exhaust Fan - On; Exhaust Dampers - Open (if so
equipped)
– OA Dampers - Closed; Return Damper - Open
– Heat - All heat stages off; Mod Heat output at 0
VDC
– Occupied/Unoccupied/VAV box output -
Deenergized
– VOM Relay - Energized
– Preheat Output - Off
– Return Fan - On; Exhaust Dampers - Open (if so
equipped)
– Return VFD - Max (if so equipped)
– OA Bypass Dampers - Open (if so equipped)
Installation
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