Rockwell Automation FANM FanMaster Energy Saving Package - Manual (Page 8)

1-2 FanMaster Overview
Allen-Bradley® FanMaster™ Energy Saving Package Installation Manual - Publication FANM-IN001B-EN-P – December, 2009 PN-65329
FanMaster Externally
Mounted Components Temperature Sensors
Two temperature sensing probes are provided with FanMaster. These probes
are essential to FanMaster because the measured difference in temperature
between these sensors provides the command signal for the fan speed. The
temperature sensors are typically mounted on the outside of the Constant
Air Volume HVAC unit, with the sensing probe penetrating into the air flow
inside through a hole drilled into the side of the HVAC enclosure.
The placement of the Mixed Air sensor should be selected after examining
the interior of the HVAC unit to ensure that the probe is located in a position
that will accurately measure the temperature of the combined outside and
return air before entering the heating and cooling section. Avoid a location
that is in the upper, lower or edge portion of the air stream and one which
may be unduly influenced by the air entering the unit from the outside air
damper. If the Mixed Air temperature probe does not accurately reflect the
average temperature entering the heating and cooling elements, the fan
speed will not be set properly.
The supply air sensor should be mounted from 6 inches to 5 feet
downstream of the final heating or cooling element. Because the
temperature of the air can be warmer at the top of the air stream and cooler
at the bottom, the probe should be mounted as close to the vertical center of
the air flow as possible.
Carbon Dioxide Sensor
The CO
2
sensor (if installed) is usually mounted in the room return air flow
of the HVAC unit prior to mixing with outside air. Alternatively, the CO2
sensor can be mounted directly on the return air duct work serving a specific
area that is most likely to be affected by high CO2 concentrations during
occasions of high occupancy. This will ensure that FanMaster will allow full
fan speed and normal ventilation when and where it is most needed. This is
the most typical installation.
Alternatively, the CO
2
sensor can be mounted directly in the conditioned
space in an area that is most likely to be affected by high CO
2
concentrations during occasions of high occupancy. This will ensure that
FanMaster will allow full fan speed and normal ventilation when it is most
needed.
It may be desirable to invest in individual CO
2
room monitors for critical
locations. It has been found that certain buildings lack adequate ventilation
prior to installation of FanMaster. If FanMaster seems to be running in CO
2
override even during periods of low occupancy, it is advised that you seek
help from an HVAC air quality professional for advice on how to best
rectify the ventilation problems.