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FAXA-SVX01B-EN
Operation
sequence of
operation
UNIT OFF sequence “A”
When complete system shut down is
required, the following sequence is used.
• supply fan – off
• outside air dampers – closed
• heat – all stages – off, modulating heat
output at 0 vdc
• occupied/unoccupied output –
deenergized
• VO relay –energized
• exhaust fan (field-installed) – off
• exhaust damper (field-installed) – closed
PRESSURIZE sequence “B”
This override sequence is for use when a
positively pressured space is desired
instead of a negatively pressurized space.
• supply fan – on
• outside air dampers – open
• heat – all stages – off, modulating heat
output at 0 vdc
• occupied/ unoccupied output – energized
• VO relay – energized
• exhaust fan (field-installed) – Off
• exhaust damper (field-installed) – closed
EXHAUST sequence “C”
With the building’s exhaust fans running
and the unit’s supply fan off, the
conditioned space becomes negatively
pressurized. This is desirable for clearing
the area of smoke when necessary (i.e.,
from an extinguished fire, to keep smoke
out of areas that were not damaged).
• supply fan – off
• outside air dampers – closed
• heat – all stages – off, modulating heat
output at 0 vdc
• occupied/unoccupied output –
deenergized
• VO relay – energized
• exhaust fan (field-installed) – on
• exhaust damper (field-installed) – open
PURGE sequence “D”
This sequence is for purging air out of a
building before coming out of unoccupied
mode of operation. Also, it can purge
smoke or stale air.
• supply fan on
• outside air damper – open
• heat: all stages off, modulating heat
output at 0 vdc
• occupied/unoccupied output energized
• VO relay energized
• exhaust fan (field-installed) on
• exhaust damper (field-installed) open
PURGE sequence “E”
This sequence uses supply air control for
smoke control.
• supply fan on
• outside air dampers open
• heat: all stages off, modulating heat
output at 0 vdc
• occupied/unoccupied output energized
• VO relay energized
• exhaust fan (field-installed) on
• exhaust damper (field-installed) open
Note: Each system (cooling, exhaust,
supply air, etc.) within the unit can be
redefined in the field for each of the five
sequences, if required. Also the defini-
tions of any or all of the five sequences
may be locked into the software by
simple key strokes at the human inter-
face panel.
Generic Building Automation System
Module (GBAS) Option
The generic building automation system
module (GBAS) provides broad control
capabilities for building automation
systems other than a Tracer Summit
system. Use a field provided
potentiometer or a 0-5 vdc signal to any
of the GBAS inputs, to access the
following inputs and outputs listed in the
paragraphs below.
GBAS analog inputs
These four analog inputs can be
configured to any of the following:
(1) occupied zone cooling
(2) unoccupied zone cooling
(3) uccupied zone heating
(4) unoccupied zone heating
(5) SA cooling setpoint
(6) SA heating setpoint
(7) space static pressure setpoint
(8) SA static pressure setpoint
GBAS binary outputs
Each of the five (5) relay outputs can be
mapped to any/all of the available
diagnostics.
Demand limiting binary input
This function is operational on units with a
GBAS and reduces electrical
consumption at peak load times. There
are two types of demand limiting, 50%
and 100%. When demand limiting is
needed, mechanical cooling and heating
operation are either partially (50%), or
completely disabled (100%) to save
energy. The demand limit definition is
user definable at the human interface
panel. Demand limit binary input accepts
a field supplied switch or contact closure.
When the need for demand limiting
discontinues, the unit’s cooling/heating
functions will (again) fully enable.
Evaporator Coil Frost Protection
Frostat™
A temperature sensor on the evaporator
determines if the coil is getting close to a
freezing condition. Mechanical cooling
capacity is shed as necessary to prevent
icing.
The Frostat™ system eliminates the
need for hot gas bypass and adds a
suction line surface temperature sensor
mounted near the TXV bulb location to
shut off cooling when coil frosting
conditions occur. The supply fan does not
shut off and will de-ice the coil. Timers
prevent the compressors from rapid
cycling.
Occupied/Unoccupied Switching
There are four ways to switch occupied/
unoccupied:
(1) programmable night setback sensor
(2) field-supplied contact closure
(hardwired binary input to RTM)
(3) Tracer Summit or other BAS (via LCI-I
with LonTalk DAC profile)
(4) factory-mounted time clock
Field supplied occupied/unoccupied input
on the RTM
This input accepts a field supplied switch
or contacts closure such as a time clock.
Tracer System
The Tracer system can control the
occupied/unoccupied status of the fresh
air unit.
Factory Mounted Time Clock
A time clock can control the
occupied/unoccupied status of the
fresh air unit.
Timed Override Activation - ICS
This function is operational whenever the
unit’s RTM module board is used as the
zone temperature sensor source, which
can be set at the human interface panel.
Initiate this function by pressing the
override button on the zone sensor, to
switch the unit to the occupied mode. Unit
operation (occupied mode) during timed
override will terminate by a signal from
Tracer.
Summary of Contents for FADA
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