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14-Burner Control A3
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at disconnect
switch(es). Unit may have multiple power
supplies.
IGNITION CONTROL A3
FLAM
E
Line voltage
FIGURE 4
The main control box (see figure 2) houses the burner
control A3.
The ignition control provides four main functions: gas
valve control, blower control, ignition, and flame sensing.
The control has a green LED to show control status (table
1).
The unit will usually ignite on the first trial and A3 allows
three trials for ignition before locking out. The lockout time
is 1 hour. After lockout, the ignition control automatically
resets and provides three more attempts at ignition. Man-
ual reset after lockout requires removing power from the
control for more than 1 second or removing the thermostat
call for heat for more than 1 second but no more than 20
seconds. 24 volt thermostat connections (P2) and heating
component connections (J1) are made through separate
jackplugs. See table 2 for thermostat terminations and ta-
ble 3 for heating component terminations.
LED
CAI Line
LED
Slow Flash
Fast Flash
Staedy Off
Staedy On
2 Flashes
3 flashes
4 Flashes
5 Flashes
P2 TERMINAL DESIGNATIONS
Pin #
1
2
3
4
5
6
7
J1 TERMINAL DESIGNATIONS
Pin #
1
2
3
4
5
6
Flame rectification sensing is used on all ZGB units. Loss
of flame during a heating cycle is indicated by an absence
of flame signal (0 microamps). If this happens, the con-
trol will immediately restart the ignition sequence and then
lock out if ignition is not gained after the third trial. See
System Service Checks section for flame current mea-
surement. The control shuts off gas flow immediately in
the event of a power failure. Upon restoration of gas and
power, the control will restart the ignition sequence and
continue until flame is established or system locks out for
one hour.
Page 26
TABLE 1
STATUS
Normal operation. No call for heat
Normal operation. Call for heat.
nternal Control Fault, No Power To
Board or Gas Valve Relay Fault
Control Internal Failure
Lockout. Failed to detect or sustain
flame
Rollout switch open / Prove switch
open or closed.
Primary High Limit switch open
Flame sensed but gas valve not open
TABLE 2
Function
R 24 Volts to thermostat
W1 Heat Demand
Y Cool Demand
C Common
G Indoor Blower
BL OUT Indoor Blower Relay
W2 Second Stage Heat
TABLE 3
Function
Limit Switch On
Rollout Switch / Prove Switch Out
Gas Valve Common
Gas Valve Out
Rollout Switch / Prove Switch In
Limit Switch In
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