Orion System RNE Modular Controller - Manual (Page 60)

Zone
Zone
SEQUENCE OF OPERATION
RNE Modular Controller Field Technical Guide 60
Primary Modulating Heat and Secondary Heat with
Staged Gas or Electric Heat
The Modulating Heating Proportional Window is used to determine the
signal to the Primary Heat Source and is user-adjustable. The Heating
Stage Control Window is used to determine stage up and stage down
of the Secondary Heat Source. In the Heating Mode, the Primary Heat
Source will modulate to achieve the Active Supply Air Temperature
Setpoint. When the Primary Heat Source reaches 100%, the Heating
Stage Up Delay begins. If the Primary Heat Source is still at 100% after
the Heating Stage Up Delay expires, the Secondary Heat Source will
activate. The Primary Heat Source will then modulate to achieve the
Active Supply Air Temperature Setpoint. If the Secondary Heat Source
is activated and the Primary Heat Source has modulated to 0%, the
Heating Stage Down Delay will begin. If the Primary Heat Source is
still at 0% after the Heating Stage Down Delay expires, the Secondary
Heat Source will deactivate. If the Supply Air Temperature rises above
the Active Supply Air Temperature Setpoint plus the Heating Stage
Control Window, the Primary Heat Source will modulate to 0% to allow
the Supply Air Temperature to cool off.
Heat Pump Operation
The RNE can be confi gured to control a Heat Pump. The compressors
are used for both Heating and Cooling. With the RNE Controller, the
Reversing Valve is activated during Heating operation as the default
because
AAON ® units are typically built to fail to Cooling operation. The
Reversing Valve can be confi gured to activate during Cooling operation
for equipment that is built to fail to Heating operation.
Auxiliary Heating Stages are confi gured as Heat Relays and are used to
supplement the Compressor Heating Stages. If the unit is not equipped
with Auxiliary Heating Stages, Heating Relays do not need to be con-
fi gured in order for the unit to provide Compression Heating. Auxiliary
Heating can also be Modulating heat in the form of SCR Electric, Hot
Water, or Steam.
The Cooling and Dehumidifi cation Modes operate in the same manner
as described under the Cooling and Dehumidifi cation titled sections on
pages 53-58 of this manual. In the Heating Mode, the RNE activates the
Reversing Valve and stages compressors to provide Heating if the Out-
door Air Temperature is above the OAT Cooling Lockout Setpoint. The
compressor heating stages are activated in the same manner as described
in the Cooling Mode of Operation, in this case to maintain the Active
Supply Air Heating Setpoint. Staged or Modulating Auxiliary Heat can
be activated to supplement Compressor Heating in order to achieve the
Active Supply Air Setpoint if the Outdoor Air Temperature is below the
OAT Heating Lockout Setpoint. If the Outdoor Air Temperature is below
the OAT Cooling Lockout Setpoint, only Auxiliary Heating will occur.
If the Outdoor Air Temperature is above the OAT Heating Lockout, only
Compressor Heating will occur.
Emergency Heat stages can also be confi gured. If the Outdoor Air
Temperature is above the Compressor Lockout Temperature, Emer-
gency Heating is disabled. If the Outdoor Air Temperature is below the
Compressor Lockout Temperature, Emergency Heating is enabled and
can stage up after Auxiliary Heat.
NOTE: If the RNE Controller is used to control a Water Source
Heat Pump unit, the Compressor Lockouts are ignored.
Since Emergency Heat can only be used below the
Compressor Lockouts, Emergency Heat is therefore not
available.
If a heat pump unit is used in a VAV application using Supply Air Tem-
pering, then Morning Warm-Up mode will only use Auxiliary Heat.
Heating for the Supply Air Tempering operation will only use Auxiliary
Heat (and Emergency Heat if available).
For RNE applications with an installed Suction Pressure Transducer, a
Head Pressure Module and a Head Pressure Transducer(s), a Defrost
Mode is available during the Heat Pump Heating operation. The RNE
Controller converts the Suction Pressure to a Suction Temperature. A
user-adjustable Suction Temperature Setpoint determines when the
unit will go into Defrost Mode during Heat Pump Heating. The unit
will operate in Defrost Mode for 10 minutes or until the Head Pressure
reaches 450 PSIG.
An Adaptive Defrost Adjustment confi guration is available that will
automatically adjust the length of the Defrost Timer (interval between
Defrost Modes) depending on if the unit stays in Defrost Mode for the
full 10 minutes or leaves the Defrost Mode early because of reaching a
Head Pressure of 450 PSIG. If Adaptive Defrost is confi gured and the
Defrost Mode is terminated because the 10 minute timer has elapsed,
this could indicate that the unit needs more Defrost time. In this case,
the Adaptive Defrost Adjustment value will be subtracted from the
original Defrost Timer to shorten the interval between Defrost Cycles.
If the Defrost Cycle is terminated between the 8th and 9th minute, the
Defrost Timer value will not be changed. If the Defrost Cycle is termi-
nated before the 8th minute, this could indicate that the Defrost Timer
is too short. In this case, the Adaptive Defrost Adjustment value will
be inversely proportionally added to the original Defrost Timer as the
termination time shortens from 8 minutes to 0 minutes.
NOTE: For other details specifi c to Water Source Heat Pump
operation, see the Water Source Heat Pump Module
Troubleshooting Section on page 78.
Morning Warm-Up Mode Operation
When the RNE Controller is confi gured as a VAV unit (Cooling only)and
switches to the Occupied Mode of Operation (not Override Mode), the
unit compares the Return Air Temperature to a Morning Warm-Up Target
Temperature. If the Return Air Temperature is below this Setpoint, the
Warm-Up Mode is initiated. This Mode remains in effect until the Return
Air Temperature rises above the Target Temperature or a user-adjustable
Time Period expires. Warm-Up Mode is not initiated by Push-Button
Overrides or Unoccupied Heating demands. The Outdoor Air Damper
remains closed during Warm-Up Mode.
Once the Warm-Up Mode has been terminated, it cannot resume until
the unit has been through a subsequent Unoccupied Mode. Only one
Warm-Up Mode is allowed per Occupied cycle.
Heating Mode and Morning Warm-Up