48/50PG and PM
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 (Fan Enable for IAQ), 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 is 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 less than the configuration 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).
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%. The seven 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. Fan speed is always calculated by evaluating the current applicable conditions. Each fan speed “mode” is evaluated independently, and the highest fan speed is used. For example, if an IAQ Override event occurs during 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 (Configuration→ECON→E.CTL = 1 (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.
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