Specifications

47
Table 56 — IGC LED Indicators
NOTES:
1. There is a 3 second pause between error code displays.
2. If more than one error code exists, all applicable error codes
will be displayed in numerical sequence.
3. Error codes on the IGC will be lost if power to the unit is
interrupted.
RELOCATE SAT (Supply Air Temperature) SENSOR FOR
HEATING-LINKAGE APPLICATIONS — On CCN instal-
lations employing ComfortID™ terminals, the factory SAT
location must be changed to a new location downstream of the
unit’s heating system. The ComfortID terminal controls read
the SAT value for their “proof-of-heat” sequence before termi-
nals open to Minimum Heating positions during unit heating
sequence.
Determine a location in the supply duct that will provide a
fairly uniform airflow. Typically this would be a minimum of
5 equivalent duct diameters downstream of the unit. Also, care
should be taken to avoid placing the thermistor within a direct
line-of-sight of the heating element to avoid radiant effects.
Run a new two-wire conductor cable from the control box
through the low voltage conduit into the space inside the build-
ing and route the cable to the new sensor location.
Installing a New Sensor
— Procure a duct-mount temperature
sensor (Carrier P/N 33ZCSENPAT or equivalent 10-k ohm at
25 C NTC [negative temperature coefficient] sensor). Install
the sensor through the side wall of the duct and secure.
Re-Using the Factory SAT Sensor
— The factory sensor is
attached to one of the supply fan housings. Disconnect the sen-
sor from the factory harness. Fabricate a mounting method to
insert the sensor through the duct wall and secure in place.
Attach the new conductor cable to the sensor leads and ter-
minate in an appropriate junction box. Connect the opposite
end inside the unit control box at the factory leads from MBB
J8 terminals 11 and 12 (PNK) leads. Secure the unattached
PNK leads from the factory harness to ensure no accidental
contact with other terminals inside the control box.
MORNING WARM UP — Morning Warm Up is a period of
time that assists CCN linkage in opening up downstream zone
dampers for the first heating cycle of a day.
The Morning Warm Up Period is CCN linkage mode “2”
and is relayed in the following conditions:
• Temperature Compensated Start Mode is active AND Heat
Mode in effect AND LAT is warm enough or is to be
ignored due to placement.
• The unit just went into occupied mode and there has been
no cooling mode yet and a heat cycle occurs or was in
progress when the unit went occupied.
In both cases, if and when the heat mode terminates, a heat
cycle has occurred and any subsequent heat cycles will not be
treatedasamorningwarmupperiod.
Static Pressure Control — Variable air volume (VAV)
air-conditioning systems must provide varying amounts of air
to the conditioned space. As air terminals downstream of the
unit modulate their flows, the unit must simply maintain
control over duct static pressure in order to accommodate the
needs of the terminals, and therefore to meet the varying
combined airflow requirement.
A 48/50AK,AY unit equipped with a duct pressure control
system is provided with an optional variable frequency drive
(VFD) for the supply fan. The speed of the fan can be con-
trolled directly by the ComfortLink™ control. A transducer is
used to measure duct static pressure. The signal from the trans-
ducer is received by the ECB-2 board and is then used in a PID
control routine that outputs a 4 to 20 mA signal to the VFD.
Generally only VAV systems utilize static pressure control.
It is required because as the system VAV terminals modulate
closed when less air is required, there must be a means of
controlling airflow from the unit, thereby effectively prevent-
ing overpressurization and its accompanying problems.
The three most fundamental configurations for most appli-
cations are Configuration
→ SP → SP.CF, which is the static
pressure control type, Configuration → SP → SP.S,usedto
enable the static pressure sensor, and Configuration → SP
→ SP.SP, the static pressure set point to be maintained.
OPERATION — On units equipped with a VFD and a proper
static pressure sensor, when SP.CF, SP.S and SP.SP are config-
ured, a PID routine periodically measures the duct static
pressure and calculates the error from set point. This error at
any point in time is simply the duct static pressure set point
minus the measured duct static. The error becomes the basis for
the Proportional term of the PID. The routine also calculates
the integral of the error over time, and the derivative (rate of
change) of the error. A value is calculated as a result of this PID
routine, and this value is then used to create an output signal
used to adjust the VFD to maintain the static pressure set point.
Static pressure reset is the ability to force a lowering of the
static pressure set point through an external control signal.
Explained in detail further below, the control supports this in
two separate ways; through a 4 to 20 mA signal input wired to
the unit’s isolator board input terminals (thereby facilitating
third party control), or via CCN.
In the latter case, this feature leverages the communications
capabilities of VAV systems employing ComfortID™ termi-
nals under linkage. The system dynamically determines and
maintains an optimal duct static pressure set point based on
the actual load conditions in the space. This can result in a
significant reduction in required fan energy by lowering the set
point to only the level required to maintain adequate airflow
throughout the system.
SETTING UP THE SYSTEM — The options for static
pressure control are found under the Local Display Mode
Configuration
→ SP. See Table 57.
LED INDICATION ERROR CODE
On Normal Operation
Off Hardware Failure
1 Flash Fan On/Off Delay Modified
2 Flashes Limit Switch Fault
3 Flashes Fame Sense Fault
4 Flashes Five Consecutive Limit Switch Faults
5 Flashes Ignition Lockout Fault
6 Flashes Ignition Switch Fault
7 Flashes Rollout Switch Fault
8 Flashes Internal Control Fault
9 Flashes Software Lockout