ENVI
®
Control
32
exceeds this setting, CL will be displayed in the lower left of the ENVI display and the boiler will be
unable to cycle until the switch boiler counter is below this parameter again. Every minute of cycle
run time this counter is decreased by one (1).
1.8.4.7.13 Hys quic start {Hysteresis quick start}, Quic start tme {Quick start time}, Hys quick stop
{Hysteresis quick stop}, Quic stop time {Quick stop time}
For those instances where the load changes rapidly quick start / quick stop parameters bypass the
Wait blr sw on
and Wait blr sw off
parameters to allow the system to respond more quickly.
When the header temperature falls below the HDR SETPOINT by the HYS QUIC START
temperature setting, the control uses the QUIC START TIME (time delay for quick start) to stage on
member boilers. The master control shortens the interval between boiler starts, allowing the
system to catch up more quickly.
When the header temperature rises above HDR SETPOINT by the HYS QUIC STOP temperature
setting, the control uses the QUIC STOP TIME (time delay for quick stop) to stop the member
boilers. The master control shortens the interval between boiler stops, allowing the system to
prevent overshooting the HDR SETPOINT.
1.8.4.7.14 Lo Load waiting {Low Load Waiting}
The LOLOAD WAITING is set on the master boiler control and used in conjunction with the various
other low load settings found in the cascade menu on the member boiler(s). This parameter allows
the master to turn on a boiler that is below the HDR SETPOINT temperature if this time interval has
passed. The master sends the header setpoint to the member boilers; each member boiler control
monitors its own supply temperature to detect if a low load condition exists.
This and additional low load settings are described in the Cascade Settings section of this manual.
1.8.4.7.15 Start rotation
The START ROTATION is an On/Off selection. When this selection is ON; a sub-setting is required
to be defined to determine the frequency of lead rotation from the current operating lead to the next
boiler. The Master boiler will always remain the master and will be the lead boiler initially, after each
rotation frequency period elapses, the next sequential boiler will rotate as the lead boiler. This
rotation will continue until the master is once again the lead & then repeat.
Note: All settings and operating sensors will be maintained on the original master boiler
1.8.4.7.16 No boiler on wait
The NO BLR ON WAIT is the time the ENVI
®
Control waits to override a hold from a member boiler.
For example, a low return temperature hold for a non-condensing boiler in a hybrid system will
trigger the NO BLR ON WAIT function. After the NO BLR ON WAIT period expires, the ENVI
®
Control allows the non-condensing boiler to start.
1.8.4.7.17 Anti windup
This ON/OFF setting
prevents “wind up” from occurring in the PID loop. The anti-windup setting is
factory set to OFF; when set to ON, anti windup helps prevent the lead boiler from ramping to 100
percent fire rate before staging on the member (slave) boilers to satisfy the setpoint by restarting
the PID logic at the beginning of every cycle.
1.8.4.7.18 Lead Boiler
This parameter will appear when the START ROTATION parameter is set to OFF. This allows the
user to define a fixed boiler as the lead. There will be no rotation of lead boiler when this occurs.
When START ROTATION is set to ON; this parameter is not available.
