Note: It is best practice to leave HtS and LtS at their default values, unless you intend to use
the restricted adjustment mode.
Note: If you use the Temperature Setback feature in the Restricted Adjustment mode, the
effective On and OFF setback values (On + tBs and OFF + tBs) can be greater than the selected
HtS value or less than the selected LtS value.
Temperature Setback (tSb)
Select a temperature value for setting back the On and OFF temperature values. When
a user-supplied switch between the BIN and COM terminals closes, note the following
changes:
• The Main screen displays BIN in the upper-right corner of the LCD.
• The temperature setback feature is enabled and the control uses the effective On and OFF
setback values (On + tSb and OFF + tSb) to control the relay.
Note: The control displays only the original On and OFF values in the normal and setback
modes. The effective setback On and OFF values (On + tSb and OFF + tSb) never display on the
control LCD.
The temperature setback adjustment range is from -50°F to 50°F (-30°C to 30°C). Typically,
heating applications require a negative temperature setback (tSb) value, and cooling
applications require a positive value.
Sensor Offset Adjustment (So)
Sensor offset allows you to compensate for any difference between the displayed
temperature value and the temperature sensed at the A99 sensor. Select a temperature
value to offset the temperature displayed on the LCD from the temperature sensed at the
sensor. The sensor offset adjustment range is from -5°F to 5°F (-3°C to 3°C) in 1° increments.
Backlight Brightness Level (bLL)
The backlight brightness level feature allows you to adjust the LCD backlight intensity. At
level 0 the backlight is off. Level 10 is the brightest backlight setting and the system default.
The selected backlight brightness level is applied to the LCD during normal operation.
When you enter the programming menus to set up the control or press any key, the LCD
automatically goes to the brightest level. If you do not press a key for 30 seconds, the main
screen displays and the backlight setting reverts to the selected brightness level.
Defrost Cycle Time (dFt)
Select the time in minutes that the defrost cycle overrides On and keeps the relay Off. The
dFt value can be between 1 minutes and 99 minutes. When the defrost cycle is On, the
control is NOT running and the LCD displays the following screens: dEF (defrost mode),
minutes remaining, and the temperature at the sensor. When the dFt is complete, the
control returns to normal (On/Off cycle) operation.
Defrost Interval (dI)
Select the time in hours between the start of a defrost cycle and the next defrost cycle. The
dI value can be set to 0 or 2 hours to 24 hours.
Note: At the initial power On, the defrost interval (dI) does NOT have a defrost cycle (dFt). The
subsequent defrost intervals begin with the selected dFt.
Setting the dl value to 0 eliminates regular or timed defrost cycles. You can still start or stop
a defrost cycle by setting the SdF parameter or by using the binary input.
11A421 Series Electronic Temperature Controls with Off-Cycle Defrost Installation Guide
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