Orion System RNE Modular Controller - Manual (Page 62)

Zone
Zone
SEQUENCE OF OPERATION
RNE Modular Controller Field Technical Guide 62
When the temperature at the Reset Source is at the Reset Source Low
Setpoint, the Supply Air Temperature Setpoint would be reset to the
Supply Air High Setpoint. When the temperature at the Reset Source is
at the Reset Source High Setpoint, the Supply Air Temperature Setpoint
would be reset to the Supply Air Low Setpoint. When the temperature
at the Reset Source is in between its Low and High Setpoints, the Sup-
ply Air Setpoint will be proportionally reset between its High and Low
Setpoints. When the unit is in the Vent Mode or Vent Dehumidifi cation
Mode, the Supply Air Temperature Setpoint will be calculated to be
halfway between the HVAC Mode Enable Setpoints. If Dehumidifi cation
Priority has been confi gured and the unit is in Heating Dehumidifi cation
or Cooling Dehumidifi cation Mode, the Supply Air Temperature Setpoint
is proportionally reset in the same way as in the Heating and Cooling
Modes described above in this paragraph.
If the Supply Fan VFD Signal is confi gured as the Reset Source, then
separately, for the heating mode and the cooling mode, you will need
to enter a Low and High VFD Signal Setpoint and a Low and a High
Supply Air Setpoint. This creates a range of VFD Signal Setpoints and
a range of Supply Air Temperature Setpoints. As the VFD Signal varies
within its range, it will proportionally reset the Supply Air Temperature
Setpoint within its range. For example, in the Cooling Mode, when the
Supply Fan VFD Signal is at its low setpoint, the Supply Air Cooling
Setpoint will be reset to its high setpoint; when the Supply Fan VFD
signal is at its high setpoint, the Supply Air Cooling Setpoint will be
reset to its low setpoint. In the heating mode, the Supply Air Heating
Setpoint reset would react in the opposite fashion with the VFD signal at
its highest setpoint the Supply Air Heating Setpoint is reset to its highest
setpoint, and with the VFD signal at its lowest setpoint the Supply Air
Heating Setpoint is reset to its lowest setpoint. In either mode, if the
VFD signal is halfway (for instance) between the Low Signal Setpoint
and the High Signal Setpoint, the Supply Air Setpoint would be reset
to halfway between its High and Low Setpoint. If Dehumidifi cation
Priority has been confi gured and the unit is in Heating Dehumidifi ca-
tion or Cooling Dehumidifi cation Mode, the Supply Air Temperature
Setpoint is proportionally reset in the same way as in the Heating and
Cooling Modes described above in this paragraph. When the unit is in
the Vent Mode or Vent Dehumidifi cation Mode, the Supply Air Tem-
perature Setpoint will be calculated to be halfway between the HVAC
Mode Enable Setpoints.
If a Remote Reset Signal is confi gured as the Reset Source, a 0-5 or 0-10
VDC signal can be used to reset the Supply Air Temperature Setpoint
(set jumper to 0-10V). Separately, for the Heating Mode and the Cool-
ing Mode you will need to enter a Low and a High Supply Air Setpoint.
As an example when using a 0-5 VDC signal, when the Reset Signal is
at 0 VDC, the Supply Air Setpoint will be at its lowest setpoint for both
Heating and Cooling. When the Reset Signal is at 5 VDC, the Supply
Air Setpoint will be at it highest setpoint for both Heating and Cooling.
As the voltage signal changes between 0 VDC and 5 VDC, the Supply
Air Setpoint will be proportionally reset between the Low and High
Supply Air Temperature Setpoint for both Heating and Cooling. If De-
humidifi cation Priority has been confi gured and the unit is in Heating
Dehumidifi cation or Cooling Dehumidifi cation Mode, the Supply Air
Temperature Setpoint is proportionally reset in the same way as in the
Heating and Cooling Modes described above in this paragraph. When
the unit is in the Vent Mode or Vent Dehumidifi cation Mode, the Supply
Air Temperature Setpoint will be calculated to be halfway between the
HVAC Mode Enable Setpoints.
Air Flow Monitoring, Supply Fan, and Duct Static Pressure
Air Flow Monitoring/Control
The RNE Controller with the E-BUS Distribution Module can moni-
tor airfl ow of the outside air, the supply air, and the return/exhaust
air streams by utilizing EBTRON
® GTN116 and GTC116 Airfl ow
Monitoring Stations. The RNE will control the Outdoor Air Damper to
maintain an Outdoor Air CFM Setpoint. No other control functions are
available at this time.
Supply Fan Control
Any time the Supply Fan is requested to start, a timer is checked to make
sure the Supply Fan has been off for at least 1 minute. This 1-minute
delay is a protection against rapid cycling of the Supply Fan. Once the
1-minute delay has been satisfi ed, the Supply Fan relay is activated and
all other outputs are verifi ed to be in the off condition for a period of 1 to 2
minutes. This short period of Supply Fan-Only Operation serves to purge
the stagnant air from the duct before any Heating or Cooling occurs.
Normally, the Supply Fan runs continuously during the Occupied Mode
of operation. If the fan is only required to run in the Occupied Mode
during Heating, Cooling, or Dehumidifi cation Modes, the RNE can be
confi gured for Fan Cycle Mode.
Duct Static Pressure Control
The RNE Controller reads and controls Static Pressure in the duct system
if the Supply Fan has been confi gured for Duct Static Pressure Control.
Any time the Supply Fan is operating, the RNE Controller is controlling
Duct Static Pressure. The Duct Static Pressure Setpoint and Deadband
limits are user-adjustable along with a Control Interval. This Control
Interval is the amount of time that elapses between each adjustment to
the Duct Static Pressure Control Output Signal. The default period is 10
seconds and should not be changed unless close observation reveals that
the Supply Fan is hunting and not maintaining a stable pressure read-
ing. The Static Pressure Control Output Signal can be used to control a
Supply Fan VFD (Direct Acting Operation) or a Zoning Bypass Damper
Actuator (Reverse Acting Operation).
The Duct Static Pressure Control Output Signal is a non-confi gurable
Direct Acting Signal (0-10 VDC). This Output Signal can be used to
directly connect to a Supply Fan VFD. The Output Signal increases
(increases VFD Speed) if the Duct Static Pressure is below the Duct
Static Pressure Setpoint by the Deadband amount, and the Output Signal
decreases (decreases VFD Speed) if the Static Pressure is above the
Setpoint by the Deadband amount.
Since the Duct Static Pressure Control Output Signal is a non-confi g-
urable Direct Acting Signal (0-10 VDC), when you are using a Zoning
Bypass Damper Actuator to control the Duct Static Pressure, you must
set up the Zoning Bypass Damper Actuator or the Zoning Bypass Damper
so that it is Reverse Acting in operation. The Output Signal increases
(closes Zoning Bypass Damper) if the Duct Static Pressure is below the
Duct Static Pressure Setpoint by the Deadband amount, and the Output
Signal decreases (opens Zoning Bypass Damper) if the Static Pressure
is above the Setpoint by the Deadband amount.