Rockwell Automation FANM FanMaster Energy Saving Package - Manual (Page 9)

FanMaster Overview 1-3
Allen-Bradley® FanMaster™ Energy Saving Package Installation Manual - Publication FANM-IN001B-EN-P – December, 2009 PN-65329
Pressure Sensor (Optional)
In certain applications it may be necessary or desirable to maintain a
positive building pressure relative to the outside air. A pressure sensor can
be ordered with FanMaster which monitors the differential pressure
between the inside and outside air. When the differential pressure is lower
than a user specified setpoint, the FanMaster will override to 100% fan
speed to try to restore the desired minimum pressure differential. One
typical scenario where pressure override might occur is when a loading
dock door is opened to allow for a delivery, and additional airflow is
required to restore the pressure differential when the door closes. The sensor
requires connection to two lengths of 1/4 inch OD plastic tubing which
sample the inside and outside air pressure at their respective termination
points. You may need to experiment with the location of the tubing since
normal wind and airflow often causes localized air pressure deviations
around a building which may result in inaccurate pressure measurements.
You may find that the HVAC unit fan speed has no measurable affect on
building pressure. In this case turn off the pressure mode completely and do
not use the sensor.
When using a pressure sensor the Constant Ventilation mode described
below is not available.
Damper Position Indicator Switch
Many existing HVAC systems have a feature known as “economizer mode”
or “free cooling mode”. These systems monitor the outside air temperature
and humidity and when conditions are such that the outside air can be used
to provide cooling (instead of using the cooling element) the existing typical
system will open the outside air damper fully to allow maximum use of this
“free” cooling. FanMaster uses a Damper Position Indicator switch to
indicate when the existing control system is in economizer mode. The
switch is installed on the outside air damper in a location that causes its
contacts to close when the damper opens beyond the normal 10%
ventilation position.
In order to take full advantage of economizer mode, FanMaster increases
the speed of the fan to 100% until the existing control determines that
economizer mode is no longer appropriate. The economizer control will
then return the damper to its normal ventilation position and the contacts in
the damper position indicator switch will open. This signal is sent to
FanMaster, which allows the fan to return to its normal reduced speed and
damper override functions.
The switch must be installed in a position that will actuate when the damper
opens. It may be mounted directly on the damper blades, on the damper
actuator arms or linkage, or on the center axle of a damper blade section.
Because there are many different damper systems in use, the installation
may require fabrication of a custom linkage or mounting method if no
suitable location is available.