Rockwell Automation FANM FanMaster Energy Saving Package - Manual (Page 14)

1-8 FanMaster Overview
Allen-Bradley® FanMaster™ Energy Saving Package Installation Manual - Publication FANM-IN001B-EN-P – December, 2009 PN-65329
Supply Air Low Limit / High Limit Override
The supply air limit override setup values allow you to configure FanMaster
to run the fan at full speed as the supply air temperature reaches a low or
high limit. The default values are suitable for use in most cases. It is
desirable to limit the supply air temperature extremes to protect the HVAC
equipment. Increasing the fan speed to 100% as the temperature approaches
limits will provide this protection.
The supply air low temperature limit specifies the supply air temperature
below which FanMaster will run the supply air fan at full speed (100%) to
avoid freezing up the cooling system.
The supply air high temperature limit specifies the temperature above which
FanMaster will run the supply air fan at full speed (100%) to avoid
overheating the heating system.
In many installations the supply air limit overrides will never take effect
because the system is not capable of achieving the override temperature
limits under normal conditions. Also, the override temperatures will never
be used in two state heating or cooling systems since the fan is already at
maximum speed when the delta T exceeds the delta T minimum
temperature value.
Outside Air Damper Override
Additional savings can be achieved if the installation includes an outside air
damper with spring return-to-close, the existing system provides a signal to
open the damper to its normal outside air position (typically 10%), and the
supply override relay can be wired in a manner that interrupts the existing
control signal.
Systems Without Outside Air Dampers
FanMaster can be used with HVAC systems that do not have an outside air
damper. Even though no savings can be realized by reducing outside air,
reduced fan speeds will still provide energy savings.
Heating Only or Cooling Only HVAC Systems
The setup screens provide the ability to indicate whether or not heating or
cooling elements are used in the HVAC system. Setting these fields to “No”
indicates that heating or cooling is not available and will disable that portion
of the FanMaster operation and savings calculator.