Bell & Gossett S14333 Technologic 5500 Series ZoneSav Controller - Manual (Page 12)

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Setpoint Indexing is implemented when the system
supply temperature degrades to the point where it is
impossible to meet the setpoints in the system. In
this condition, the valve would normally go to the
wide open position to try to meet the setpoints.
However, if setpoint indexing is used, the ZoneSav
Controller can modify the setpoints in order to remain
in control. A warning is generated while the controller
is in this mode of operation.
To edit the fields, press NO and ENTER. Press YES
and ENTER to accept the values. See Table 11 for a
description of the Setpoint Indexing variables.
3.3.2.3 Heat/Cool
From the PID Setup Menu, shown in section 3.3.2,
press 3 and ENTER to get to the Heat/Cool screen
shown below.
Application Type: #
1:Heating
2:Cooling
Ok ? (Y/N)
Press YES and ENTER to accept the values and
return to the PID Setup Menu shown in section 3.3.2,
or press NO and ENTER to edit the field.
3.3.2.4 Auto Tune
From the PID Setup Menu, shown in section 3.3.2,
press 4 and ENTER to get to the Auto Tune screen
shown below.
Auto-Tune Select: #
ZS: (Message)
1=Start
ZR: (Message) 0=Stop
FL: (Message) Ok ? (Y/N)
Press YES and ENTER to return to the PID Setup
Menu shown in section 3.3.2. Press NO and ENTER
to edit the field. See Table 13 for a description of the
Auto Tune variables.
Auto-Tuning is used to find the optimal P, I, and D
values for the system being tuned. When the
process is started, the valve will be forced wide open.
It will remain there until the zone supply setpoint is
met. Then the valve will be forced closed. It will
remain there until the setpoint is no longer met. This
cycle will repeat 5 times. The message will change
from "Tune" to either "Comp" or "Err" indicating com-
pletion. Tuning of the zone return and flow values will
then commence. If an error occurs, auto tuning will
be aborted. The valve position and process variables
can be viewed in other screens during auto tuning.
The optimal P, I, and D will automatically be used.
These gains can be viewed or modified from the PID
Gains screen shown in section 3.3.2.1.
The controller must be stopped and in manual opera-
tion mode to begin the auto tuning process. Also,
make sure the zone return and zone supply setpoints
are set up and that they are realistic values. See sec-
tion 4.3 for more information on modifying the set-
points. The setpoint used for flow will be 90% of the
flow limit value. Make sure that the flow limit value is
set up and realistic. See section 3.3.4 for more infor-
mation on setting up a flow limit.
If a flowmeter is not used, the Auto-Tuning process
should be stopped manually. Wait for the message
for "FL" to be "Tune". Then enter a zero in the Auto-
Tune Select field to stop the process. The gains for
zone supply and zone return will still be optimized
and used.
Variable Unit Description Default Value Range Field Value
Sup Idx °F Zone supply index: the difference between the system 0 0-20
supply temperature and the zone supply setpoint that will
be maintained. 0 will disable this mode of operation.
ZSTmr min Zone supply index timer: controlle will remain in zone 0 0-99
supply index mode for the duration of this timer
Ret Idx °F Zone return index: the difference between the system 0 0-20
supply temperature and the zone return setpoint that will
be maintained. 0 will disable this mode of operation.
ZRTmr min Zone return timer: controller will remain in zone supply 0 0-99
index mode for the duration of this timer
Table 11: Setpoint Indexing Variables
Variable Description Default Value Range Field Value
Application Select 1 if system is for heating, or select 2 if system 2 1-2
Type is for cooling
Table 12: Heat/Cool Variable
Variable Description Default Value Range
Auto-Tune Select 1 = Start Auto Tune Process 0 0-1
0 = End Auto Tune Process
Message Stop = Stopped, Tune = Tuning, Err = complete with error, N/A N/A
Comp = complete
Table 13: Auto Tune Variables