Ingersoll-Rand ReliaTel, Manual, Page: 64 / 176

64 RT-SVD03L-EN
Table 20. Service test (continued)
(c) Units with enhanced dehumidification only will not perform this step
during service test.
Failure and Override Modes
• Supply fan proving - If there is a supply fan failure
condition all outputs associated with the supply fan
output control will be de-energized and the PWM
output will be at 0%.
• The supply fan will energize at high speed as a
result of all failure modes that require the supply
fan to operate.
Single Zone VAV
ReliaTel
™
controls platform will support Single Zone
VAV (SZVAV) as an optional unit control type in order
to meet ASHRAE 90.1 in addition to other multi-speed
indoor fan configurations. Basic control will be a hybrid
VAV configured unit that provides discharge
temperature control to a varying discharge air
temperature setpoint based on space temperature.
Concurrently, the unit will control and optimize the
supply air fan speed to maintain the Zone Temperature
(ZT) to a zone temperature setpoint.
Supply Fan Output Control - VFD
Equipped Units
Normal SZVAV units will be equipped with a VFD
controlled supply fan. The fan is controlled via the 0-10
Vdc RTOM J11-2 and the RTRM J1-11. The control will
scale the output from the RTOM to adjust between the
minimum and maximum range of the VFD.
Direct Drive Backwards Curve Plenum
Fan Equipped Units
For SZVAV units configured with an BC Plenum
(Precedent™), the control outputs a 2.4-7.6 Vdc signal
from the RTOM J11-2 to cover the range of the
application designed airflow. This output is adjustable
via the RTOM R136 pot for adjusting CFM/ton. The
adjustable range for max speed output is from 3.4 Vdc
at full counter-clockwise to 7.6 Vdc at full clockwise.
PWM Controlled Motor Equipped Units
For SZVAV units configured with a PWM controlled
motor, the duty cycle of the PWM signal will be
controlled in order to vary the speed of the supply fan.
The range of the duty cycle for the PWM output will be
50-100% of user selected maximum.
Supply Fan Mode Operation
SZVAV units will utilize supply fan mode selection
using ReliaTel
™ controls for normal zone control and
will be selectable between AUTO and ON via a
connected zone sensor module or through BAS/
Network controllers.
Ventilation Control
Units configured for SZVAV control will require special
handling of the OA damper minimum position. Refer to
each section below for details on each configurable
ventilation control method.
Demand Controlled Ventilation
Units configured with DCV will invoke a new scheme
which allows variable building design and DCV
minimum positions and OA damper position target
setpoints based on the supply fan speed and space CO
2
requirements.
This new scheme will require the setting of 5 OA
damper position setpoints which will be located on the
required RTVM:
• Design Min Position @ Min Fan Speed Command
(RTVM R130)
• Design Min Position @ Medium Fan Speed
Command (RTVM R136)
• Design Min Position @ Max Fan Speed Command
(RTEM Design Min Position)
• DCV Min Position @ Min Fan Speed Command
(RTVM R41)
• DCV Min position @ Max Fan Speed Command
(RTEM DCV Min Position)
As the supply fan speed varies between 0-100%, the
building design and DCV minimum position targets will
be calculated between the user selected setpoints
based on the instantaneous supply fan speed. The
building design and DCV minimum position targets will
be used to calculate the active OA damper minimum
position target, based on the space CO
2
relative to the
Design and DCV CO
2
setpoints.
The range for the design minimum and DCV minimum
OA damper position setpoints at minimum and
medium be 0-100%, while the range at maximum fan
speed will be 0-50%.
Outside Air Damper Minimum Positions
without DCV
For units not configured with DCV, additional minimum
position setpoints to increase outdoor airflow accuracy
will be required. The operation will be similar to OA
CFM compensation on traditional VAV units with the
addition of a design minimum position setpoint at
medium fan speed. The following setpoint
potentiometers will be used on the RTEM:
• Design Min at Min Fan Speed Command (RTEM
DCV Min)
• Design Min at Medium Fan Speed Command
(RTEM DCV Setpoint LL)
• Design Min at Max Fan Speed Command (RTEM
Design Min)
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