Rockwell Automation FANM FanMaster Energy Saving Package - Manual (Page 12)

1-6 FanMaster Overview
Allen-Bradley® FanMaster™ Energy Saving Package Installation Manual - Publication FANM-IN001B-EN-P – December, 2009 PN-65329
Constant Ventilation Mode
Constant Ventilation mode can be used in specific applications requiring a
relatively constant flow of outside air be maintained for ventilation at all
times. This mode is not recommended for most installations as it precludes
the savings which may be realized by reducing the quantity of outside air
brought into the HVAC system. This is also the most difficult installation
due to the need to redirect the control signals for the outside damper control
into FanMaster and make new interconnections from FanMaster to the
outside air damper actuator.
If this mode of operation is enabled, FanMaster will continue to reduce the
fan speed to realize savings according to the Law of Affinity, but it will also
modulate the outside air damper open as the fan slows down in order to
maintain the same approximate quantity of outside air flow into the
building.
Estimated Savings Calculator
The FanMaster control system contains a calculator that provides an
estimate of the energy savings achieved by the reduction in fan speed and
reduction in outside air heating and cooling. The calculator uses the settings
provided by the user at startup and actual operating conditions, combined
with historical weather data for your selected location, to provide the
estimated cost savings achieved by FanMaster. The estimated energy costs
to run the HVAC unit with and without FanMaster are compared to
determine the savings.
FanMaster Application
Considerations Two State Heating or Cooling Control
Two state control of heating or cooling is used when the actual amount of
heating or cooling applied by the existing HVAC unit is fixed. That is, the
heating or cooling element is either on or off. FanMaster allows for the
selection of two state control for either heating or cooling or both. When
FanMaster is configured for two state control, it will run the fan at the
configured minimum speed when the temperature sensors detect that
heating and cooling are off, and will run the fan at the configured maximum
speed when the temperature sensors detect that heating or cooling is on.
This mode allows FanMaster to achieve energy savings during the time the
HVAC unit is idle and to allow maximum performance when the HVAC unit
is actively heating or cooling.
When in two state mode, the “Delta T Min” setup values for cooling and
heating determine when the fan speed transitions from “Min” to “Max”
speed. A typical value of five degrees is acceptable for most installations.
The “Delta T Max” setup values for cooling and heating have no effect on
operation in this mode, nor do any “SA (supply air) Override” settings.