Fan Operation - Multiple Fans, No Staging; Set Point And Minimum Variables; Defined Modes - Greenheck Vektor Installation, Operation And Maintenance Manual

General Electrical Controls Information

Fan Operation - Multiple Fans, No Staging

Set point and minimum variables

1. System will maintain a minimum of 3000 fpm velocity
(factory default) at the outlet of each fan, based on
the airflow monitoring station. Building Management
System (BMS) to monitor each fan nozzle actuator
feedback and keep fan speed above the minimum
required set point to maintain velocity.
2. Each fan to run at BMS defined operation for
fan on or off, and event timing, as required per
system airflow requirements. BMS is also required
to control fan speed for all fans. Bypass damper
mode reference will be determined by the following
scenario listed:
A. All fans in system running at minimum. Minimum
flow condition.
a. BMS will control fan speed and monitor nozzle
feedback as required to maintain system set point.
b. Decreased flow condition from minimum speed.
When the speed is equal to the minimum specific
fan speed and nozzle feedback is at minimum for a
set time period (user-defined), the BMS will begin to
modulate the bypass damper(s) open to assist with
pressure control.
Increased flow condition from minimum speed. If
the bypass damper(s) are at full closed for a set
time period (user-defined), the BMS will increase
fan speed and the fan control will increase the
nozzle area as required to assist with pressure
control.
c. The PID sequence to be programmed at the BMS
for the bypass damper(s) operation. The BMS to
provide fan enable and VFD speed reference.
B. Normal operation. Fan operation normal system
flow.
a. Flow requirement for system within reach of fan
operation. Fans operating will float together from
minimum speed to maximum speed to keep set
point.
b. If any of the fans run in the surge area for a set
time period, the BMS will need to add the bypass
damper(s).
c. The PID sequence to be programmed at the BMS
for the bypass damper(s) operation. The BMS to
provide fan enable and VFD speed reference.
6
VGN Technology
Definition of typical operation modes:
Mode #1: Unoccupied. Defined as no one inside the
lab(s), all lab hoods are closed.
1. Fan(s) will operate at BMS required speed and nozzle
will modulate as necessary to achieve the required
velocity out the fan(s). BMS to monitor nozzle
actuator feedback for each fan and keep fan speed
above the minimum required to maintain velocity.
2. Sure-Aire will measure airflow of the fan. VFD or the
nozzle controller for each fan will report this value to
BMS.
3. Duct pressure control, by the BMS, will modulate
bypass damper(s) as required.
Note: Follow bypass damper(s) operation
depending on number of fans running.
4. VFD speed, duct pressure control and the bypass
damper(s) operation is provided by the BMS system.
Mode #2: Occupied; no lab hoods being used.
Defined as people entering the lab(s), no work being
done at the hoods.
1. Fan(s) will operate at BMS required speed and nozzle
will modulate as necessary to achieve the required
velocity out the fan(s). BMS to monitor nozzle
actuator feedback for each fan and keep fan speed
above the minimum required to maintain velocity.
2. Sure-Aire will measure airflow of the fan. VFD or the
nozzle controller will report this value to BMS.
3. Duct pressure control, by the BMS, will modulate
bypass damper(s) as required.
Note: Follow bypass damper(s) operation
depending on number of fans.
4. VFD speed, duct pressure control and the bypass
damper(s) operation is provided by the BMS system.
Mode #3: Occupied; some or all lab hoods being
used. Defined as people in the lab(s), lab hood sashes
being used.
A. Sashes opening in the lab
1. Fan(s) will operate at BMS required speed and
nozzle will modulate as necessary to achieve the
required velocity. Typical system response should
be to increase fan(s) speed and increase nozzle
open area.
2. Sure-Aire will measure airflow of the fan. VFD or the
nozzle controller for each fan will report this value
to BMS.
3. Duct pressure control, by the BMS, will modulate
bypass damper(s) as required.
Note: Follow bypass damper(s) operation
depending on number of fans running.
4. VFD speed, duct pressure control and the bypass
damper(s) operation is provided by the BMS
system.
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