21
EXTERNAL ALARM SIGNAL — The unit controls provide
an external alarm status signal via a 115-vac output signal at
the relay board J5, available at TB2-4 and TB2-5 (common).
This signal can be forwarded to the BMS by adding a signal
relay at the alarm output, placing its coil across terminals TB2-
4 and TB2-5 and using its contacts to control a discrete input to
the BMS (see Fig. 31).
The alarm signal output is energized when any of the diag-
nostic codes is tripped.
REMOTE ECONOMIZER CONTROL — Economizer con-
trol is tightly integrated into the unit’s capacity control algo-
rithms and diagnostic routines. Consequently, control
modifications that interfere with this standard operating
sequence are not recommended.
Economizer position is determined by the unit processor
board based on current outdoor air enthalpy status and cooling
capacity demand. The economizer damper actuator is a floating
point device with an internal brake and spring return. Its posi-
tion is determined by the sequencing of relays EOR (Econo-
mizer Open Relay) and ECR (Economizer Close Relay). The
economizer’s current position is sensed by the processor board
through position feedback potentiometer P2.
Whenever the economizer position potentiometer signal is
not consistent with the processor board’s commanded position,
a fault condition is determined by the processor board and an
alarm signal is initiated. The processor board also attempts to
return the economizer damper to its fully closed position dur-
ing this fault condition by energizing the ECR relay.
Any attempt to effect an external control of the economizer
actuator will lead to an alarm condition and an automatic re-
sponse by the unit control to attempt to close the dampers.
Smoke Control Modes —
It is common practice to use
rooftop units for aid in building smoke control in the event of a
building fire. The available functions include: Fire Shutdown,
Pressurization, Evacuation, and Smoke Purge. These functions
are enhanced when multiple rooftop units are used to zone a
building.
Implementation of the various Smoke Control modes on
these units requires the installer to modify the unit wiring to
add contacts (via either manual switches or relays) that will se-
lectively interrupt and override standard factory control se-
quences. See Table 5.
Smoke control mode Pressurization requires the economiz-
er function. Evacuation and Smoke Purge modes require both
economizer and power exhaust functions. Both functions are
standard features on 48FM and 50FM,FS units. These func-
tions require factory-installed options, field-installed accesso-
ries and/or field-supplied exhaust systems on 48FK,JK and
50FK,FY,JK,JY units. Consult price pages for specific details.
FIRE SHUTDOWN MODE — Fire Shutdown mode termi-
nates all unit operation (cooling, heating, supply fan and power
exhaust). This mode prevents recirculation of contaminated air
back into the space or the admission into the space of unsuit-
able outside air.
PRESSURIZATION MODE — Pressurization mode is
intended to keep smoke out of a zone. The economizer is
required for this function. The economizer is standard on
48FM and 50FM,FS units. The economizer is a factory-
installed option on 48FK,JK and 50FK,FY,JK,JY units. Pres-
surization is accomplished by:
•
opening the economizer
•
running the supply fan (optional inlet guide vanes open
or optional VFD [variable frequency drive] at normal
duct static pressure set point)
•
shutting off the power exhaust fans (Standard on 48FM
and 50FM,FS units. Factory-installed option or field-
installed accessory on 48FK,JK and 50FK,JK units)
This allows the space to be overpressurized relative to adja-
cent zones and prevents or slows entry of smoke into this space
from adjacent zones.
EVACUATION MODE — Evacuation mode removes smoke
or undesirable air from interior spaces without reintroducing
unsuitable air. The economizer and power exhaust are required
for this function. The economizer and power exhaust are
standard on 48FM and 50FM,FS units. The economizer is a
factory-installed option and the power exhaust is a factory-
installed option or field-installed accessory on 48FK,JK and
50FK,JK units. Evacuation is accomplished by:
•
turning supply fan off
•
opening the economizer
•
running the exhaust fans
•
opening the exhaust dampers
12
15
034-048: TB3
054-104: TB4
TRANSDUCER
R
P
BMS
CONTROL
(4 TO 20 MA
OR
2 TO 10 VDC
SIGNAL)
LIGHT
4
5
TB2
TB2
RELAY
R
SIGNAL TO BMS
LEGEND
Fig. 30 — Remote SASP Wiring
P
—
Manual Potentiometer
R
—
Fixed Resistor
Field Wiring
LEGEND
Fig. 31 — External Alarm Indication
R
—
Fixed Resistor
Factory Wiring
Field Wiring
Summary of Contents for 48FK034
Page 14: ...14 Fig 20 Unit Control Box Arrangement Sizes 034 048...
Page 15: ...15 Fig 21 Unit Control Box Arrangement Sizes 054 078...
Page 16: ...16 Fig 22 Unit Control Box Arrangement Sizes 088 and 104...
Page 39: ...39 Fig 44 Modulating Power Exhaust Component Locations Sizes 034 048...
Page 40: ...40 Fig 45 Modulating Power Exhaust Component Locations Sizes 054 104 48FK 50FK JK Shown...
Page 59: ...59 Fig 57 Typical Wiring Schematic 48FK JK and 50FK FY JK JY Units 054 074 Shown...
Page 60: ...60 Fig 57 Typical Wiring Schematic 48FK JK and 50FK FY JK JY Units 054 074 Shown cont...
Page 61: ......
