55
Table 56 — Staged Gas Heat Control Steps (Configuration
HEAT
SG.CT
HT.ST = 3)
Table 57 — Staged Gas Heat Control Steps (Configuration
HEAT
SG.CT
HT.ST = 4)
INTEGRATED GAS CONTROL BOARD LOGIC
All gas heat units are equipped with one or more integrated gas
control (IGC) boards. This board provides control for the igni-
tion system for the gas heat sections. On size 020-050 low heat
units there will be one IGC board. On size 020-050 high heat
units and 060 low heat units there are two IGC boards. On size
060 high heat units there are three IGC boards. When a call for
gas heat is initiated, power is sent to W on the IGC boards. For
standard 2-stage heat, all boards are wired in parallel. For
staged gas heat, each board is controlled separately. When en-
ergized, an LED on the IGC board will be turned on. See Table
58 for LED explanations. Each board will ensure that the roll-
out switch and limit switch are closed. The induced-draft mo-
tor is then energized. When the speed of the motor is proven
with the Hall Effect sensor on the motor, the ignition activation
period begins. The burners ignite within 5 seconds. If the burn-
ers do not light, there is a 22-second delay before another 5-
second attempt is made. If the burners still do not light, this se-
quence is repeated for 15 minutes. After 15 minutes have
elapsed and the burners have not ignited then heating is locked
out. The control will reset when the request for W (heat) is
temporarily removed. When ignition occurs, the IGC board
will continue to monitor the condition of the rollout switch,
limit switches, Hall Effect sensor, and the flame sensor. Forty-
five seconds after ignition has occurred, the IGC will request
that the indoor fan be turned on. The IGC fan output (IFO) is
connected to the indoor fan input on the MBB which will indi-
cate to the controls that the indoor fan should be turned on (if
not already on). If for some reason the overtemperature limit
switch trips prior to the start of the indoor fan blower, on the
next attempt the 45-second delay will be shortened by 5 sec-
onds. Gas will not be interrupted to the burners and heating
will continue. Once modified, the fan delay will not change
back to 45 seconds unless power is reset to the control. The
IGC boards only control the first stage of gas heat on each gas
valve. The second stages are controlled directly from the MBB
board. The IGC board has a minimum on-time of 1 minute. In
modes such as Service Test where long minimum on times are
not enforced, the 1-minute timer on the IGC will still be fol-
lowed and the gas will remain on for a minimum of 1 minute.
Table 58 — 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 inter-
rupted.
RELOCATE SAT (SUPPLY AIR TEMPERATURE) SENSOR
FOR HEATING IN LINKAGE APPLICATIONS
On CCN installations employing ComfortID™ terminals, the
factory SAT location must be changed to a new location down-
stream of the unit’s heating system. The ComfortID terminal
controls read the SAT value for their “proof-of-heat” sequence
before terminals open to Minimum Heating positions during
unit heating sequence.
Determine a location in the supply duct that will provide a fair-
ly uniform airflow. Typically this would be a minimum of
STAGE
RELAY OUTPUT
CAPACITY
%
Heat 1 Heat 2 Heat 3 Heat 4 Heat 5 Heat 6
MBB-RLY8 MBB-RLY7 SCB-RLY1 SCB-RLY2 SCB-RLY3 SCB-RLY4
IGC1 MGV1 IGC2 MGV2 IGC3 MGV3
0 OFFOFFOFFOFFOFFOFF 0
1 ON OFF OFF OFF OFF OFF 25
2 ON ON OFF OFF OFF OFF 33
3 ON OFF ON OFF OFF OFF 50
4 ON ON ON OFF OFF OFF 58
5 ON ON ON ON OFF OFF 67
6 ON OFF ON OFF ON OFF 75
7 ON OFF ON ON ON OFF 83
8 ON ON ON ON ON OFF 92
9 ON ON ON ON ON ON 100
STAGE
RELAY OUTPUT
CAPACITY
%
Heat 1 Heat 2 Heat 3 Heat 4 Heat 5 Heat 6
MBB-RLY8 MBB-RLY7 SCB-RLY1 SCB-RLY2 SCB-RLY3 SCB-RLY4
IGC1 MGV1 IGC2 MGV2 IGC3 MGV3
0 OFFOFFOFFOFFOFFOFF 0
1 ON OFF OFF OFF OFF OFF 19
2 ON ON OFF OFF OFF OFF 25
3 ON OFF OFF OFF ON OFF 38
4 ON ON OFF OFF ON OFF 44
5 ON ON OFF OFF ON ON 50
6 ON OFF ON OFF OFF OFF 57
7 ON ON ON OFF OFF OFF 63
8 ON OFF ON OFF ON OFF 76
9 ON OFF ON ON ON OFF 88
10 ON ON ON ON ON OFF 94
11 ON ON ON ON ON ON 100
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
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