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Mounting the Controller
• The Digi-Span is designed to mount on a 1900 (4”x4”) electrical box.
• If the Digi-Span is to be panel mounted, or if additional room is needed for wiring, an extension skirt is available*.
• Locate the Digi-Span in a convenient location near the unit to be controlled.
• Mount the Digi-Span away from excessive heat or cold. Ambient operating temperature is from 20 to 120°F.
• After completing all the wiring connections (see below) use the two screws provided to mount the Digi-Span to the 1900 box.
Installing the Pressure Sensor
• Attach a 1/4” brass isolation tube (pigtail) to the steam header.
• Screw the pressure sensor to the pigtail. The sensor has 1/4"NPT tapered threads.
• The BLACK and RED sensor wires can be extended up to 500’ by splicing with 18 gauge shielded wire. Any other sensor
wires (green, white, or shield) and the tube are not used and do not need to be extended.
• Do not run wires in conduit with line voltage.
• The Digi-Span will operate based on the pressure it reads at the sensor location. Therefore, select a sensor location which is
representative of the entire system.
Wiring the Sensor
• The BLACK wire from the pressure transducer should be connected to the terminal marked SENSOR -.
• The RED wire from the pressure transducer should be connected to the terminal marked SENSOR +.
• The transducer wires can also be connected to the back of the Digi-Span using the Rear Wire connector*. Connect the
BLACK sensor wire to yellow Rear Wire and the RED sensor wire to the orange Rear Wire.
Wiring the Power - Digi-Span can use either 120VAC or 24VAC
120VAC
• Attach line voltage to the two blue wires extending from the back of the Digi-Span.
• Use wire nuts, or wrap the connections with electrical tape.
• Class 1 voltages must enter the enclosure through a different opening from any Class 2 wiring.
24VAC
• Use a dedicated transformer with at least a 5VA output.
• Bring 24VAC to the two screws on the front of the Digi-Span marked 24VAC.
• 24VAC can also be connected to the rear of the Digi-Span using the Rear Wire connector*. Connect the 24VAC to the violet
and gray Rear Wires.
The Digi-Span can accept only one source of power: 120VAC or 24VAC. If more than one power source is
applied, the unit may be damaged.
Wiring the Output
• The Digi-Span has two SPST (single pole single throw) relay outputs rated at 10A, 1/8 HP.
• The outputs are dry contacts only. They do not source any power.
• The Black wires are the N.O. (normally open) contacts for Output 1.
• The Red wires are the N.O. (normally open) contacts for Output 2.
• If the outputs are carrying any Class 1 voltages, then they must enter the enclosure through a different opening from any
Class 2 wiring.
* The Optional Mounting Kit includes the extension skirt, the Rear Wire connector with four wires (orange, yellow, violet, and
gray) and an input terminal cover. Order separately as HT #908520.
INSTALLATION
WARNING
2
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