Orion System RNE Modular Controller - Manual (Page 56)

Zone
Zone
SEQUENCE OF OPERATION
RNE Modular Controller Field Technical Guide 56
Once these conditions are met, the RNE Controller will activate and stage
heat as needed to try to achieve the Tempering SAT Heating Setting. If a
stage of heat or MODGAS heat overshoots the Tempering SAT Heating
Setting, the economizer will be allowed to modulate open to bring the
SAT down to the SAT Cooling Setpoint. If, after the heating minimum
run time has been satisfi ed, the economizer has not been able to bring
the SAT down within the heat staging window, then the controller will
stage down/off the heat.
If this is an Air to Air Heat Pump unit, heating for the Supply Air Tem-
pering operation will only use Auxiliary Heat (and Emergency Heat if
available). Compressor heat cannot be use for the tempering function.
NOTE: During this mode of operation, the standard Heating
Staging Window will be used.
There is a Maximum OA Damper Position During Tempering Setpoint
that allows you to set a maximum damper position the economizer can
open to while the heat is running during this tempering mode (to prevent
potential wasting of energy).
Dehumidifi cation Mode Operation
On VAV or CAV applications, the Indoor Air Humidity initiates Dehu-
midifi cation when the Indoor Air Humidity rises 5% above the Indoor
Air Humidity Setpoint during the Occupied Mode of operation and
likewise stops Dehumidifi cation when the Indoor Air Humidity drops
more than 5% below the Indoor Air Humidity Setpoint during the Oc-
cupied Mode of operation.
On 100% Outdoor Air applications, the Outdoor Air Dewpoint initiates
the Dehumidifi cation Mode when the Outdoor Air Dewpoint rises 2
F
above the Outdoor Air Dewpoint Setpoint during the Occupied Mode
of operation and likewise stops Dehumidifi cation when the Outdoor Air
Dewpoint drops more than 2
F below the Outdoor Air Dewpoint Setpoint
during the Occupied Mode of operation. The Outdoor Air Dewpoint is
calculated by using an Outdoor Air Temperature Sensor and an Outdoor
Air Humidity Sensor.
Chilled Water Dehumidifi cation
Once Dehumidifi cation is initiated, the RNE Controller will open the
Chilled Water Valve to a fi xed 100% position to provide for full moisture
removal capability.
DX Dehumidifi cation
During Dehumidifi cation, the RNE Controller will stage or modulate
compressors to maintain an Average Coil Suction Temperature (the av-
erage Coil Temperature of all compressors that are currently on) to the
Evaporator Coil Suction Temperature Setpoint. The Coil Temperature
is calculated by using a Suction Pressure Sensor and converting the
pressure to temperature. The Staging Delays, Minimum Run Times, and
Minimum Off times described in the Cooling Mode Section will also
apply during Dehumidifi cation.
If the Average Coil Temperature remains above setpoint, additional
compressor stages will be activated based on the Stage Up Delay timer. If
the Average Coil Temperature falls below the Coil Temperature Setpoint
minus the Cooling Stage Control Window, compressor stages will stage
off based on the Stage Down Delay timer.
Fixed DX Compressors
Once in Dehumidifi cation, the RNE Controller will initially bring on
half of the compressor stages. Additional stages will stage on and off
per the above staging description.
Half VFD Compressor(s) and Half Fixed Compressor(s)
2 Compressor Units (RNE 55-105)
The VFD Compressor will modulate as needed to maintain the
Coil Temperature Setpoint. If the compressor signal reaches
100%, the Stage Up Timer will begin. If the Stage Up Delay
period elapses and the compressor signal is still above 100%, the
Fixed Compressor will stage on. The VFD Compressor will then
be allowed to modulate between 70% and 100% to maintain the
Average Coil Temperature at the Coil Temperature Setpoint.
If the VFD Compressor modulates down to 70% for the Stage
Down Delay, the Fixed Compressor will stage off. If the VFD
Compressor modulates down to 0% for the Stage Down Delay
period, it will stage off.
4 Compressor Units (RNE 120-140)
The two VFD Compressors (both driven out of the Analog Out-
put #1) will be enabled together and will modulate to maintain
the Average Coil Temperature at the Coil Temperature Setpoint.
If the compressor signal reaches 100%, the Stage Up Timer will
begin. If the Stage Up Delay period elapses and the compressor
signal is still at 100%, the 3
rd compressor (fi xed) will be enabled.
The VFD Compressors will then be allowed to modulate be-
tween 70% and 100% to maintain the Average Coil Temperature
at the Coil Temperature Setpoint. This stage up would be re-
peated for the 4
th compressor (fi xed) with the VFD Compressors
again allowed to modulate between 70% and 100%.
If all four compressors are on and the VFD Compressor signal
modulates down to 70% for the Stage Down Delay, the 4
th
compressor will stage off while the VFD Compressors can again
modulate between 70% and 100%. This would be repeated to
stage off the 3
rd compressor. The VFD Compressors will then be
allowed to modulate from 0% to 100%. If the VFD Compres-
sors modulate down to 0% for the Stage Down Delay, they will
stage off.
Full VFD Compressors
2 Compressor Units (RNE 55-105)
The 1 st VFD Compressor will be driven out of Analog Output
(AO) #1, and the 2 nd VFD Compressor will be driven out of AO
#2. The 1 st VFD Compressor will modulate to maintain the Coil
Temperature Setpoint. If the compressor signal reaches 100%,
the Stage Up Timer will begin. If the Stage Up Delay period
elapses and the compressor signal is still above 100%, the 2
nd
VFD Compressor will stage on. The 1 st VFD Compressor will
then be locked at 100%, while the 2 nd VFD Compressor is al-
lowed to modulate as needed to maintain Average Coil Tempera-
ture at the Coil Temperature Setpoint.
Dehumidifi cation Mode