Velocity Pressure Control; Programming; Two Room Taps - Loren Cook Vari-Flow Specification And Installation Instructions

Two Room Taps

The Two Room Taps maintain a constant differential pres-
sure between two rooms. This constant differential pressure
enables the controller to monitor and regulate the pressure
through the Pressure Controller when placed at a remote lo-
cation. To connect the Two Room Taps:
• Use a 1/8" (3.175 mm) tubing to connect between the
pressure tap in the high pressure room and the HIGH
pressure port on the Pressure Controller.
• Use a 1/8" (3.175 mm) tubing to connect between the
pressure tap in the low pressure room and the LOW
pressure port on the Pressure Controller.
Com
24V~
Prs +
Rev
Dir
Ext
Kcom
Knc
Kno

Velocity Pressure Control

One Duct Static Tap and One Duct Total Tap
The One Duct Static Tap and One Duct Total Tap maintain
a constant velocity pressure in a duct. This constant velocity
pressure enables the controller to modulate the airflow auto-

Programming

Press the menu button
the next step. Use the arrow keys to change the value of the current menu item. Press and hold an arrow key to scroll rapidly
through the values. Changes are automatically saved. The Vari-Flow Pressure Controller automatically exits the menu after 20
seconds of inactivity.
Display
Step
Pr:X.XXX
1
Sp:X.XX
Deadband
2
(range: 0.000-0.243)
Response Speed:
3
(range: 1-25)
4
Cntl Out
5
Direct Act:
6
Reverse Act:
7
Contact:
8
Contact On:
9
Contact Off:
VARI-FLOW PRESSURE CONTROLLER IO&M
Static Pressure Tap
Low Pressure Port
1/8" (3.175mm) Tubing
High Pressure Port
Total Pressure Tap
to enter programming mode. Once in programming mode, the menu button always advances to
Description
Operation Mode & Setpoint Adjustment
When 24 Vac is supplied to the unit, the SPC displays the actual
pressure (Pr) and the setpoint of the static pressure (Sp). Use the arrow
keys to change the setpoint.
Deadband Adjustment
Not generally important for EC motor control
Response Speed Adjustment
Prevents unjustified changes due to a temporary surge of static
pressure, which could affect the system. To increase system stability,
we recommended setting the Response Speed to lower end of range
(setting 1 or 2).
Output Signal Adjustment
The configuration of the output signal applies to both direct acting and
reverse acting.
Direct acting output configuration
Reverse acting output configuration
Relay configuration
Relay SETPOINT (Sp) to come ON
Relay SETPOINT (Sp) to turn OFF
matically to compensate for filter or coil loading. To connect
the Duct Static and Total Tap:
• Use a 1/8" (3.175 mm) tubing to connect between the
total pressure tap and HIGH pressure port on the Pres-
sure Controller.
• Use a 1/8" (3.175 mm) tubing to connect between the
static pressure tap and LOW pressure port.
Total
Pressure Tap
In this configuration, the Pressure Controller maintains a
velocity pressure by measuring and maintaining the differ-
ence between total and static pressure read at the HIGH and
LOW pressure ports. To set up the controller, calculate the
required velocity pressure based on the intended CFM and
duct area using the following formula:
Set the desired pressure setpoint parameters from the Pro-
gramming menu (see Programming). To verify the airflow
calculation, take external CFM measurements and calculate
the velocity pressure until the desired airflow is achieved.
Increments of 0.01
Units - in w.c. (inches of water column)
Range - 0.00 to 1.99
Default: 0.014 (SPC 1.0), 0.0014 (SPC 0.1)
Increment: 0.005 (SPC 1.0), 0.0005 (SPC 0.1)
1 to 25 (factory setting: #2)
1 lowest: (100 mV/sec, 100 seconds for a 0-10 Vdc output).
25 fastest: (1.78 V/sec, 5.6 seconds for 0-10 Vdc output).
▲ or ▼ = 0-10 Vdc / 2-10 Vdc
▲ or ▼ = Vdc or mA (Set to Vdc for EC motor control)
▲ or ▼ = Vdc or mA (Set to Vdc for EC motor control)
Direct or Reverse
Contact Direct: 0.31-2.00 "wc Contact Reverse: 0.00-0.31 "wc
Contact Direct: 0.00-0.31 "wc Contact Reverse: 0.31-2.00 "wc
3
Air Flow
Duct
Pressure Tap
Low Pressure Port
High Pressure Port
where A is the duct area in ft
Values
B51004-002
Static
2