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EXTERNAL ALARM SIGNAL — The unit controls pro-
vide an external alarm status signal via a 115-vac output sig-
nal at the relay board J5, available at TB2-4 and TB2-5
(common). This signal can be forwarded to the BMS by add-
ing 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 di-
agnostic codes is tripped.
REMOTE ECONOMIZER CONTROL— Economizer con-
trol is tightly integrated into the unit’s capacity control al-
gorithms and diagnostic routines. Consequently, control
modifications that interfere with this standard operating se-
quence are not recommended.
Economizer position is determined by the unit processor
board based on current outdoor air enthalpy status and cool-
ing capacity demand. The economizer damper actuator is a
floating point device with an internal brake and spring re-
turn. Its position is determined by the sequencing of relays
EOR (Economizer 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 po-
sition, 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 during this fault condition by energizing the ECR
relay.
Any attempt to effect an external control of the econo-
mizer actuator will lead to an alarm condition and an auto-
matic response 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, andSmoke 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
selectively interrupt and override standard factory control se-
quences. See Table 5.
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
unsuitable outside air.
PRESSURIZATION MODE — Pressurization mode is in-
tended to keep smoke out of a zone. Factory-installed op-
tional economizer is required for this function. Pressuriza-
tion is accomplished by:
• opening the economizer (option)
• running the supply fan (optional inlet guide vanes open or
optional VFD (variable frequency drive) 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 ad-
jacent 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. Factory-installed, optional economizer with
optional or accessory power exhaust are required for this func-
tion. Evacuation is accomplished by:
• turning supply fan off
• opening the economizer (option required for this function)
• running the exhaust fans (must be provided via option or
accessory)
• opening the exhaust dampers
SMOKE PURGE MODE — Smoke Purge mode removes
smoke from the interior spaces and replaces it with fresh out-
side air. Factory-option economizer with optional or acces-
sory power exhaust are required for this function. Smoke purge
is accomplished by:
• turning supply fan on
• opening the economizer (option required for this function)
• running the exhaust fans (must be provided via option or
accessory)
• 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)
LEGEND
P—Manual Potentiometer
R—Fixed Resistor
Field Wiring
Fig. 30 — Remote SASP Wiring
LIGHT
4
5
TB2
TB2
RELAY
R
SIGNAL TO BMS
LEGEND
R—Resistor (Factory Installed)
Factory Wiring
Field Wiring
Fig. 31 — External Alarm Indication
21