7
Differential
The differential controls how many pounds the system can fluctuate around the set points. It is used to prevent short
cycling of the units being controlled.
In the heating mode, a stage will energize when the sensor pressure falls to the set point minus the differential. The stage will
open when the pressure rises to the set point (see Example on opposite page).
In the cooling mode, a stage will energize when the sensor pressure rises to the set point. The relay will open when the
pressure falls to the set point minus the differential.
To set the differential, use the following steps:
1. Digi-Span should be displaying sensor pressure.
2. Press and release the center button three times. The display will change to show
dIF
. Wait 2 seconds or press the
UP
or
DOWN
button and the differential will be displayed.
3. Press and hold either the
UP
or
DOWN
button until the desired differential is displayed.
4. Wait approximately 10 seconds. If the differential was changed, the display will flash. Then the Digi-Span will return to
displaying the sensor pressure. (If you dont want to wait 10 seconds, press the center button once for Offset or twice to
display sensor pressure immediately.)
Offset
The offset value calibrates the sensor pressure reading by the number of pounds selected.
To adjust the offset, use the following steps:
1. The Digi-Span should be displaying sensor pressure.
2. Press the center button four times and release it. The display will change to show
OFF
. Wait 2 seconds or press the
UP
or
DOWN
button and the offset will be displayed.
3. Press and hold either the
UP
or
DOWN
button until the desired offset is displayed.
4. Wait approximately 10 seconds. If the offset was changed, the display will flash and then show the corrected sensor
pressure. (If you dont want to wait, press the center button once.)
OUTPUT
Light Indication
The red
OUTPUT
light indicates how many stages are active at any given time. When the red light is:
OFF - Neither output stage is active. Both the Black and Red wires are open.
FLASHING - One output stage is active. Either the Black or the Red wires are continuous, but not both.
ON - Both output stages are active. Both the Black and Red wire are continuous.
