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Fan Enable (Analog IAQ Sensor)
The DCV algorithm will operate whenever the building is
occupied and the indoor fan is operating or whenever the IAQ
algorithm has caused the indoor fan to operate. The configuration
Configuration→AIR.Q→IA.FN
determines whether or not the IAQ algorithm can turn on the
indoor fan. If the indoor fan is not operating, the economizer
position will be zero. The damper position may exceed
Configuration→AIR.Q→EC.MN to provide economizer cooling.
IA.FN = 0 (Never)
When IA.FN = 0, the IAQ algorithm can never turn on the fan.
IA.FN = 1 (Occupied)
When IA.FN = 1, the IAQ algorithm will turn on the indoor fan
whenever the building is occupied and IAQ/OAQ differential
greater than the configuration Configuration→AIR.Q→ DF.ON
(Fan On AQ Differential). The indoor fan will turn off when the
IAQ/OAQ
differential
is
Configuration→AIR.Q→DF.OF (Fan Off AQ Differential).
IA.FN = 2 (Always)
The indoor fan performance for IA.FN = 2 is the same as the
performance when IA.FN = 1 except the algorithm is not limited to
occupied periods only. The fan can be triggered on when the space
is occupied or unoccupied.
Fan Enable (Switch Input)
The DCV algorithm will operate whenever the building is
occupied and the indoor fan is operating or the whenever the IAQ
algorithm has caused the indoor fan to operate. The configuration
Configuration→AIR.Q→II.FN (IAQ Switch Input Fan CFG)
determines whether or not the IAQ algorithm can turn on the
indoor fan. If the indoor fan is not operating, the economizer
position will be zero. The damper position may exceed
Configuration→AIR.Q→EC.MN to provide economizer cooling.
II.FN = 0 (Never)
When II.FN = 0, the IAQ algorithm can never turn on the fan.
II.FN = 1 (Occupied)
When II.FN = 1, the IAQ algorithm will turn on the indoor fan
whenever the building is occupied and IAQ is high. The indoor fan
will turn off if IAQ returns to normal.
II.FN = 2 (Always)
The indoor fan performance for II.FN = 2 is the same as the
performance when II.FN = 1 except the algorithm is not limited to
occupied periods only. The fan can be triggered on when the space
is occupied or unoccupied.
EnergyX
For units equipped with the EnergyX factory installed option, there
will be an EnergyXv2 Supplement Installation Instructions in the
unit's information packet. Refer to this supplement for details on
how the ERV operates relative to the base unit.
Adaptive Fan
The Adaptive Fan Option is a new method of controlling the
supply fan in a typical constant volume rooftop unit. This control
method employs a Variable Frequency Drive (VFD) to operate the
supply fan at different speeds in order to achieve energy savings
through reduced fan power. This method is specifically not
concerned with controlling static pressure in the supply duct, but
rather with setting different fan speeds for different operating
conditions, such as ventilation mode or part−load mechanical
cooling. This option should not be confused with a linearly
variable VFD concept − the different speeds are pre−programmed
per condition; there is no linear−modulation of fan speed.
Adaptive Fan is enabled by setting Adaptive Fan Operation to yes,
(Configuration→A.FAN→AF.EN = Yes).
(Fan
Enable
for
IAQ),
less
than
the
configuration
The adaptive fan function is NOT a Variable Air Volume (VAV)
function. The fan adapts its speed to one of nine based on mode
and current state to satisfy a demand. The nine speeds consist of
two hard coded values and seven configurable values. The two
hard coded values are 0% (or OFF) and 100%.
configurable fan speeds are: Ventilation (FS.VN), IAQ Override
(FS.AQ), Free Cool Lo (FS.E1), Free Cool Hi (FS.E2), Mech
Cooling (FS.CL), Heating (FS.HT), and Reheat2 (FS.RH).
The VFD is powered by the indoor fan contactor and is always on
unless the unit is in test mode. When the thermostat or space
sensor control conditions require the fan on, the VFD will then
ramp to desired speed.
evaluating the current applicable conditions.
"mode" is evaluated independently, and the highest fan speed is
used. For example, if an IAQ Override event occurs during
is
Ventilation mode, the fan speed is set to the higher of the two
(FE.VN or FS.AQ)
NOTE: Adaptive Fan operation and Analog economizer actuator
operation are mutually exclusive because they both use the AO1
output on the ECB. Priority is given to Adaptive Fan, so if the unit
is configured for Adaptive Fan (Configuration→A.FAN→AF.EN
= Yes), the software will automatically set the actuator control
method
to
digital
(DIG/POSITION).
Fan Speed − Ventilation (FS.VN)
This configuration defines the fan speed used in Ventilation
(fan−only) mode. Ventilation mode is when the supply fan is
running, but there is no demand for heating or cooling.
Fan Speed − IAQ Override (FS.AQ)
This configuration defines the fan speed used when an IAQ
Override is active. This pertains only to the Override function of
IAQ (Configuration→AIR.Q→IA.CF = 2) (Override IAQ) or
(Configuration→AIR.Q→II.CF = 3 or 4) (Override N/O or N/C),
not the DCV or Minimum Position functions.
Fan Speed − Free Cool Lo (FS.E1)
This configuration defines the fan speed used when in Free
Cooling at low cool mode. Refer to the Economizer Controls
Operation section for details on low cool mode.
Fan Speed − Free Cool Hi (FS.E2)
This configuration defines the fan speed used when in Free
Cooling at high cool mode. Refer to the Economizer Controls
Operation section for details on high cool mode.
Fan Speed − Mech Cooling (FS.CL)
This configuration defines the intermediate fan speed used when
mechanical cooling is being requested. Fan speed is based on how
many cooling stages the unit has, how many cooling stages are
being requested, and how many reheat stages are being requested.
If the unit only has one circuit of cooling, then the fan speed will
be 100% whenever that stage is requested. If the unit has more
then one circuit of cooling but only one is being requested, the fan
speed will be set to FS.CL. Any time more than one stage is
requested the fan speed will be set to 100%. On Humidi−MiZert
equipped units fan speed is more complex. Refer to the FS.RH and
Table 11 for details.
34
Fan speed is always calculated by
Each fan speed
(Configuration→ECON→E.CTL
The seven
=
1
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