62-11389
4
−
9
4.7. USER SELECTED OVERRIDE OPERATION
Three optional software override programs are avail-
able to the user. These programs include: Supply Air
Limit Control, Temperature Range Lock and Pro-
ductShield. Information on how the unit operates under
these programs is provided in the following sub-para-
graphs.
4.7.1 Supply Air Limit Control
Supply Air Limit Control is available when the set point is
at or between 32 to 65
F (0 to 18.4
C) and the unit is
operating in cool.
Supply Air Limit is NOT a positive temperature control,
drift above and below the Supply Air Limit will be seen as
the system balances out.
Supply Air Temperature control will be accomplished by
varying the position of the CSMV.
Supply Air Limit Configuration values can be set to allow
for a different limit for Start-Stop than used in
Continuous Run.
Supply Air Limit Control is set using the PERISHABLE
SENSITIVE PRODUCT Functional Parameter (which
can be set to OFF or ON), and the SUPPLY AIR LIMIT
FOR START-STOP Operation Configuration or
SUPPLY AIR LIMIT FOR CONTINUOUS Operation
Configuration (each of which can be set from 0 to
-21.6
F [0 to -12
C]).
NOTE
These values are all negative (except for 0),
therefore, when the value is added to the set
point, the result will be a temperature that is less
than the set point.
When the PERISHABLE SENSITIVE PRODUCT
Functional Parameter is set to OFF, the supply air
temperature will be the coldest temperature of 32
F
(0
C) OR the calculated value of Set Point minus the
configured Supply Air Limit value.
When the PERISHABLE SENSITIVE PRODUCT
Functional Parameter is set to ON, the supply air
temperature will be the calculated value of set point
minus the configured Supply Air Limit value.
Supply Air Limit controls the temperature of the supply
air as it leaves the evaporator so that it does not go
colder than the configured Supply Air Limit value below
set point.
NOTE
The 9
F value used in the following examples is
not necessarily a recommend setting, but is
only used to show how the Supply Air Temper-
ature Limit is calculated.
EXAMPLE 1: Perishable Sensitive Product Functional Parameter =
OFF
Supply Air coldest temperature limit is the colder temperature of:
+32
F
OR
Set point minus configuration value for Supply Air Limit
Sample Calculations:
Set point
50
F
45
F
40
F
33
F
Supply Air Limit Configuration Value
-9
F
-9
F
-9
F
-9
F
Set point minus Supply Air Limit
41
F
36
F
31
F
24
F
Coldest Supply Air Temperature allowed
32
F
32
F
31
F
24
F
EXAMPLE 2: Perish Sensitive Product Functional Parameter =
ON
Supply Air will be limited to Set point minus configuration value for Supply Air Limit.
Sample Calculations:
Set point
50
F
40
F
33
F
Supply Air Limit Configuration Value
-9
F
-9
F
-9
F
Set point minus Supply Air Limit
41
F
31
F
24
F
Coldest Supply Air Temperature allowed
41
F
31
F
24
F
