Differential Pressure Sensor (DPS)- Installation & Initial Setup

3 Minute Read

| Overview

Differential Pressure Sensor (DPS) extends the sensor capabilities of 75F controllers. Its use opens an array of additional applications from flow sensing in variable air volume (VAV) boxes to monitoring filter performance in air handling units (AHU). The compact profile and rugged construction of DPS allow it to be mounted on the sides of VAV boxes, hard supports, or rafters.  

The DP sensor connects to the 75F controllers like the SmartNode's sensor bus and works seamlessly 'out of the box with the Facilisight suite of applications. Thoughtful design touches include, large cutouts making it easy to install when wearing gloves.

Powered by the 75F sensor bus, the DP sensor uses a 3-Pin Molex connector for power and communication. The differential pressure pickup ports work with both 4mm and 1/4" tubing via an adapter. 

| Precautions

• Failure to wire devices with the correct polarity when using a shared transformer may result in damage to any device powered.
• Do not mount the tubing so that the inside or the outside tube ends line directly with the line of a breeze or draft.
• Turn off the power before wiring, never connect or disconnect the wiring with the power turned on.
• Do not allow live wires to touch the circuit boards.

| Mounting

Mounting of DPS

• Mount the Differential Pressure Sensor using two #8-1.5-inch self-tapping screws as shown above.
• Install the transmitter (Factory- calibrated) vertically with the air inlet nozzles, perpendicular to the ground.
• Open both pressure ports to the atmosphere, to adjust the zero.

Mounting of Air pick-up pipe

• Mount the air pick-up pipe to the air inlet nozzles provided on the DPS. To fix the pipe, push one end of the flexible pipe till the edge butts out to the back of the nozzle and the other end to the crossflow tubes or pitots, that comes pre-installed with the VAV boxes.

| Wiring

• Connect the power and communication wire, from the master device's 3-Pin sensor port to the daisy chain inlet port, as shown above. 
• Wire more sensors from the outlet port of the DPS as shown above, using the below wiring harness.

Set the daisy chain setting option to yes or no, if the differential pressure sensor is a terminal device in the bus or not, using the switch shown in the image.

• Turn off the power. Connect one end of the 75F cable to one end of the RTS port on the SmartNode and the other end to the IN port of the DPS.
• Power the DPS through this cable.
• Connect the cable to the OUT port of the DPS and RTH sensor, to add another RTH sensor.

For more information on Daisy, Chaining capabilities refer to Daisy Chaining Capabilities of Sensors

| More Information

Enable RTH Sensor Communication

• Set the Daisy Chain switch to Yes, to enable RTH sensor communication.
• Connect the static tube to “- “and the total pressure pipe to “+”, for differential pressure calculation in the duct.