• Sensor Offset Adjustment (
So
)
• Sensor Failure Option (
SF
)
• Backlight Brightness Level (
bll
)
See
Parameter codes and modes of operation
for more information regarding parameter codes, usable
parameter values, and default values.
Figure 7: Navigating the Advanced menu
Viewing and changing values in the
Advanced menu
In this task you access the Advanced menu and view and
change the parameter values.
1.
On the Main screen, press and hold
Down
and
Up
simultaneously for 5 seconds.
Un
displays on the LCD,
which is the first parameter code screen displayed in
the Advanced menu.
2.
To scroll through all of the advanced parameter
codes and display the preferred code, press
Down
or
Up
.
3.
With the preferred parameter code displayed, press
MENU
to display the current parameter value for the
code.
4.
With the current parameter value displayed, press
Down
or
Up
to scroll through all of the parameter
code’s usable values and display the preferred value.
5.
With the preferred parameter value displayed, press
MENU
to save the displayed value and go to the next
parameter code.
A421 Series Control with Free-Cooling
Ventilation
When the sensed temperature is warmer than the On
value, the relay remains On. See Figure 8.
Control behavior for preferred temperature
range
When the sensed temperature is in between the On and
OFF values, the following behavior is enforced:
• The fan relay is On for at least the Minimum Relay On-
Time (Ont) during a Cycle Period (cP). See Figure 8.
• The fan relay goes Off when the sensed temperature is
less than or equal to the OFF value.
• If the temperature based On-time (t1+t2) is less than
Ont, only the remaining Ont [Ont minus (t1+t2)] is
enforced at the end of the cP.
• The total On-time may exceed the Ont only when the
sensed temperature On-time (t1+t2) is greater than
Ont.
• If the fan relay is On due to the sensed temperature for
a time is greater than or equal to Ont (earlier in the cP),
then the fan relay remains OFF for the remainder of the
cP.
• The only condition that turns the fan relay On greater
than the Ont is when the sensed temperature rises to
the On value.
Control behavior for cooler than preferred
temperature range
The fan relay is On for at least the Ont (Minimum Relay
On-Time) during each Cycle Period (cP). See Figure 8.
Control behavior for extremely colder than
preferred temperature range
When the sensed temperature is less than or equal to the
Low Temperature Stop (LtS) value, the relay is On for the
Low Temperature On-Time (Ltt) each Cycle Period (cP). The
following behavior is enforced:
• The On-time is restricted to just the Ltt value whenever
the sensed temperature falls below the LtS value. See
• The Ltt is the minimum time required to ventilate the
controlled space.
A421 Series Electronic Temperature Controls with Cycle Timer Installation Guide
8
