Greenheck Vari-Green Control - Constant Pressure/Air Flow Control (479653) - Manual (Page 9)

2 Setpoint Edit Menu Parameters
Parameter Name Values Default Description
Pressure setpoint
-1.00 to
+1.00 in WC
(-249 to +249Pa)
-0.10 in. WC
(-24.9Pa)
Pressure setting the control will maintain. Only available in [Pressure
Mode] and when [Local Setpoint] is selected.
Airflow setpoint
Airflow setting the control will maintain. Only available in Airflow mode
and when [Local Setpoint] is selected.
Cutout %
* 20 – 100% 20%
When the output value falls below this setting, the output will turn off
after the delay time has elapsed. This is used to turn the primary fan
off in times of no demand. Only available in [Pressure mode].
Cutout delay time 0-300 seconds 30 seconds
The output value must be below the cutout threshold for this amount
of time before the fan will turn off.
Only available in [Pressure mode].
Cutout return
pressure setpoint
-0.250 in WC–
0.250 in WC
(-62.27 to
+ 62.27Pa)
inlet mode:
0.01 in. WC
(2.49Pa)
outlet mode:
-0.01 in. WC
(2.49Pa)
This is the threshold that the secondary fan(s) output must pass for
the primary fan to turn back on while in cutout mode.
• Inlet Mode: Measured static pressure must be more positive than
the return from cutout value.
• Outlet Mode: Measured static pressure must be more negative than
the return from cutout value.
Only available in [Pressure mode].
Override
output %
0, 20-100% 100%
When the digital input is closed, the fan output will be set to this value
until the digital input is opened.
Minimum
output %
20-100% 20% Sets the minimum output value of the controller during [Run] mode.
Maximum
output %
20-100% 100% Sets the maximum output value of the controller during [Run] mode.
Digital output
set %
20-100%
20% (pressure
mode) 97%
(airflow mode)
The digital (relay) output will close when the fan output is above this
value. Useful as a dirty filter switch in [Constant Airflow] mode.
* More Information about the cutout feature:
• The cutout % value is only valid for a discreet
pressure set point. If the pressure setpoint is
changed, the cutout % must be adjusted as well.
Make sure the pressure setpoint is correct before
continuing to set the cutout.
• Steps to determine cutout %:
o Verify pressure setpoint is correct and that the
entire system is in the state where it is desired
for the fan to turn off (such as no secondary fans
operating).
o While viewing the display of the control, make
sure that the Output % value is shown. If not,
touch the up/down arrow on the control until the
Output % value is shown.
o After the pressure has stabilized at the setpoint
(usually 2-3 mins), take note of the Output %.
The value will fluctuate slightly, a mental average
is adequate.
o The recommended cutout value is 1-2 percentage
points above the value noted in the previous
step.
o EXAMPLE: With no secondary fans in the system
operating, the controller is running the primary
fan at 43.5% to maintain the pressure setpoint.
The cutout value is set at 45%. Now, any time
that the output of the control drops below 45%
(after the cutout delay time has elapsed) the fan
will turn off.
• When the Output % is less than the Cutout %, the
LED on the control will flash Yellow, signaling that
the Cutout Delay Timer has started. When the
Cutout Delay Time has elapsed, the LED will turn
solid Yellow and the Output % will show OFF.
• Troubleshooting:
o If the fan will not turn off when desired, the
cutout value is set too low.
o If the fan turns off when it is not desired, the
cutout value is set too high.
o If the fan turns off as desired, but does not turn
back on when desired:
- The cutout return pressure setpoint can be
adjusted up or down to match the system
needs.
- A pressure change must be present. If there
is nothing upstream/downstream of the
fan that will force a pressure change in the
system then the fan will not come back on
and the cutout feature should not be used.
Constant Pressure Control 9