Ingersoll-Rand ReliaTel, Manual, Page: 69 / 176

RT-SVD03L-EN 69
additional 5 minutes from the time heat is terminated
must elapse before dehumidification will be allowed.
Purge Mode (Comfort and Dehumidification)
Purge cycle operation will operate identically to purge
on non-SZVAV dehumidification units. If the Reheat
Circuit operates in one mode (dehumidification or
cooling) for a cumulative 90 minutes the unit will
initiate a 3-minute Purge cycle exactly as on non-Single
Zone VAV units with staged dehumidification.
During an active Purge Cycle the Supply Fan Speed will
operate at the appropriate speed based on the active
compressor step. If a dehumidification purge is
initiated, the unit will run at appropriate
dehumidification airflow and if performing a cooling
purge the supply fan will track based on the
appropriate minimum speed for the associated number
of compressors energized. After the Purge Cycle is
complete, the Supply Fan will be released to normal
control based on the Cooling/Dehumidification
demand.
Dehumidification - Humidistat Operation
For SZVAV units configured with modulating
dehumidification and are utilizing a Humidistat for
control, the unit will function as described above, but
instead of making an internal decision when to perform
dehumidification based on a SH value, the unit will take
requests for dehumidification from the Humidistat
input. If the Humidistat input goes active and all
conditions described above are met to allow
dehumidification, the unit will enter dehumidification
as described in "Entering Dehumidification" above. All
other normal overrides will be in effect. Once the
Humidistat input goes inactive, the unit will transition
out of dehumidification as described above in "Leaving
Dehumidification".
Other Considerations
• Any heating request will terminate
dehumidification control. If heating is active at the
time a call for dehumidification control is received
the heating operation must complete and an
additional 5 minutes from the time heat is
terminated must elapse before any form of
dehumidification will be allowed.
• Enhanced Dehumidification will not be available
with a Humidistat; however, full HGRH will.
Variable Speed (VSPD) Compressor
Control (eFlex
™ ™ )
Unit Operation
The following sections describe hardware output
requirements as well as unit control sequence of
operations.
Compressor Requirements
For ReliaTel ™ systems, the VSPD compressor will
require two signals for proper control:
• Run/Start-Stop Command (VSM Binary Output)
• Speed Signal (VSM Analog Output)
Table 22. Normal run: 3 to 5 ton units
Model
Running Frequency Voltage Range SZVAV Supply Fan Speed
MZVAV Supply Fan
Speed
Min Hz Max Hz Min Max
Min-Min
PWM
Max-Min
PWM
Min-Min
PWM
Max-Min
PWM
3 15 60 2.4 5.7 53 80 53 80
4 15 60 2.4 5.7 53 80 53 80
5 15 62 2.4 5.85 53 80 53 80
Table 23. Normal run: 6 to 10 ton units
Model
Variable Speed Compressor
SZVAV Supply Fan
Speed
MZVAV Supply Fan
Speed
Freq. Min
(Hz)
Freq. Max
(Hz)
Vdc Min Vdc Max
Min-Min
V
Max-Min
V
Min-Min
V
Max-Min
V
6 17 82 1.42 6.83 50 82 50 82
7½ 22 63 1.83 5.25 50 82 50 82
8½ 22 68 1.83 5.67 50 82 50 82
10 22 80 1.83 6.67 50 82 50 82
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