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OPERATION NOTES:
If the master boiler is turned off, fails to come on within 30 seconds, or goes to lockout while operat-
ing as the master, it will stop communicating and sequencing will be disabled. All slave boilers will
revert to their own PID settings.
Should a slave boiler fail to come on within 3 minutes, due to a burner limit being off, lockout or
associated lockout in the flame safeguard, the master will call for the next slave in the priority list.
Extended purge time in a slave’s flame safeguard control is considered normal operation and the
master will wait through the extended purge.
Although it was previously stated there can be only one master, there will be times when the user
will attempt to make a slave a master while a master is still in existence.
*
The current master will
continue to be a master until it is made a slave and the new master will continue to be a slave until no
further communications is received from the previous master. It was previously established that there
is a communication timeout of 30 seconds. It is expected the user will eventually make the former
master a slave and at that time it should stop communicating as a master and now the new master can
take control. When the new master takes control it will of course operate according to its own PID
and control under its SETPOINT 1 parameters. The former master will await commands from the
new master.
If the master boiler is switched to manual modulation it will remain as master bringing on slave boil-
ers as required. This will allow the master boiler to be "base loaded" if required, yet still control the
slaves. If a master boiler is base loaded it still continues to calculate its theoretical firing rate using
its pre-programmed PID settings. If the calculated firing rate output exceeds the ON RATE, the mas-
ter will begin to bring on the slave boilers and set their firing rate to the calculated firing rate output.
During system startup, if the master boiler is in a thermal shock state trying to get to AUTO, it will
cease communications to the slaves, allowing the slaves to operate under their own PID settings.
If the SD card is used to restore data to a PPC4000 that is operating in a sequencing environment, the
communication and sequencing sub menus should be checked and verified for proper configuration.
Within the INFO screen, the variable SEQUENCING displays the current state of the control.
0 = none (sequencing not selected)
1 = slave
2 = master
3 = none going to slave
4 = none going to master
5 = slave going to none
6 = master going to none
7 = slave going to master
8 = master going to slave
*
Note: Leaving a second burner’s lead/lag switch “on” (with LED flashing) will put it into “Lead
Standby”. If the current lead selected boilers’ FSG faults (ie. flame failure, external limits are open,
or the PPC4000 faults), the “Lead Standby” will assert itself as “Lead” once the current lead’s com-
munications is terminated.
