Carrier 50EJQ Installation, Start-Up And Service Instructions Manual page 27

POWER EXHAUST OPERATION — The optional power
exhaust packages are factory- or field-installed with ver-
tical units and optionally installed in the return air ductwork
for horizontal applications. The standard and optional
modulating power exhaust are the 2 packages available. The
modulating power exhaust package is equipped with a field-
adjustable static pressure controller which will control up to
4 power exhaust stages to maintain a building static pres-
sure. The blue sequencer located in the control box below
the control board can be adjusted by removing the covers
and adjusting the set point dial to the desired building pres-
sure. The standard power exhaust package controls up to
2 stages of power exhaust to maintain building pressure. These
power exhaust stages are staged according to a percentage
of the economizer damper position. The default values are
25% for Stage 1 and 75% for Stage 2. This package has set
points that are adjustable through software (such as Service
Tool, Building Supervisor, or ComfortWorks™).
NOTE: For 50EWQ applications, the factory-supplied wir-
ing harness will allow for return duct mounting of the power
exhaust assembly within 12 ft of the unit. The harness is
approximately 16 ft long.
SMOKE CONTROL MODES — The 50EJQ,EWQ units with
an optional expansion board perform fire and smoke control
modes. The expansion board provides 4 modes which can
be used to control smoke within the conditioned area. The
modes of operation are fire shutdown, pressurization, evacu-
ation, and smoke purge. See Table 15.
SMOKE DETECTOR — A smoke detector can be used to
initiate fire shutdown. This can be accomplished by a set of
DEVICE
Economizer
Indoor Fan/VFD
Power Exhaust (all outputs)
Heat Stages
HIR
LEGEND
HIR — Heat Interlock Relay
VFD — Variable Frequency Drive
Table 15 — Smoke Control Modes
PRESSURIZATION SMOKE PURGE
100%
ON
OFF
OFF
ON
Fig. 35 — Smoke Detector Wiring
27
normally closed pilot relay contacts which will interrupt power
from the 24-v transformer, secondary ''B'' terminal to the
control circuit breaker (CB4). See Fig. 35. The wire that con-
nects these two points is white and labeled ''W78.''
The smoke detector may be mounted in the return-air duct
or the supply duct. Carrier does not make recommendations
as to specific smoke detector location due to liability
considerations.
IAQ CONTROL — The accessory expansion board and
accessory IAQ sensor are required for IAQ control. The
Carrier sensors operate with a 4 to 20 mA signal. The 4
to 20 mA signal is connected to T11 (+) and T12 (−) on
the expansion board for the IAQ sensor, and T13 (+) and
T14 (−) on the expansion board for the OAQ sensor. The
sensor is field-mounted and wired to the expansion board
installed in the unit main control box. The IAQ sensor must
be powered by a field-supplied 24-v power supply (un-
grounded). Do not use the unit 24-v power supply to power
the sensor.
Once installed, the sensor must be enabled. The sensor is
configured with default values which may be changed through
network access software. To work properly, the IAQ sensor
high and low reference points for the sensor that is used must
match the configured values. The expansion board reacts to
a 4 to 20 mA signal from the IAQ sensor. The low reference
(4 mA output) must be configured to the minimum IAQ
sensor reading. The high reference (20 mA output) must be
configured to the maximum IAQ sensor reading.
EVACUATION
100% 100%
ON OFF
ON ON
OFF OFF
ON OFF
FIRE SHUTDOWN
0%
OFF
OFF
OFF
OFF