Ingersoll-Rand ReliaTel, Manual, Page: 68 / 176

68 RT-SVD03L-EN
is satisfied and there are no other overrides in effect,
the following transition rules shall be followed:
If (HSP+1°F) < ZT < (CSP+1°F) and SH > DhSp and the
unit is operating at Stage 1 or less of compressor
cooling, then EDh is enabled and the unit will perform
the following:
• Energize the supply fan, if not already ON, and
ramp the Fan Speed output to 56% airflow.
• Energize Stage 1 of the compressor operation.
• Command the OA damper to minimum position.
If ZT > (HSP+0.5°F) or ZT > (CSP+1.5°F) or SH < DhSp -
2%, then EDh is disabled and the unit will perform the
following when transitioning out of EDh:
Stage back to normal SZVAV cooling if ZT > (CSP+1.5°
F). Fall back to SZVAV cooling control with Stage 1
compressor operation energized and initialize DASP
Fan control to normal cooling operation.
Stage back to normal control:
• If ZT < (HSP+0.5°F), leave dehumidification and de-
energize all compressor outputs immediately and
allow the unit to transition into heat/cool mode
based on ZT. Release fan control and initialize
DASP based on active unit mode.
• If ZT > (CSP-0.5°F) and SH < DhSp - 2%, stage back
to Cool 1 and initialize DASP to active DAT.
• If ZT < (CSP-0.5°F) and SH < DhSp - 2%, leave
reheat, de-energize all compressors immediately
and allow the unit to transition into heat/cool mode
based on ZT. Initialize DASP based on active unit
mode.
If no request for active heating/cooling or fan operation
is present, the supply fan will remain energized at 56%
for 60 seconds after the compressor de-energizes.
Enhanced Dehumidifi Staged (On/
Off) HGRH
For 17 SEER SZVAV, the option will be available to
have traditional staged dehumidification with Hot Gas
Reheat (HGRH) in addition to EDh. A valid SH value will
be required, and the unit will need to be hardwired
configured for Reheat (RTOM J9-2) and the non-heat
pump configuration will need to be OPEN (RTRM J1-5)
in order to use the RTRM J2-7 output for reheat
operation
Dehumidification Transitions for Enhanced
Dehumidifi Staged HGRH
Units configured for traditional HGRH will utilize EDh
as described above as the first stage of
dehumidification control if the SH is only marginally
high (DhSp < SH
< DhSp + 2%). If the unit is running in
EDh and the SH drops to > DhSp - 2%, EDh will be
terminated and the unit will transition out of the mode
as described above. If the unit is operating in EDh and
the SH is not recovering toward the DhSp - 2%, the unit
will transition into full HGRH until the SH falls below
the DhSp - 5%. If at any time the SH value rises above
the DhSp + 2%, the unit will also transition into full
HGRH until the SH falls below the DhSp - 5%.
The mode transition details into full HGRH, as
described above for EDh, will be in effect for 17 SEER
units with HGRH when only EDh is being utilized.
However, if the unit is utilizing full HGRH, the following
transitional details will be enforced:
If DhSp < SH < DhSp + 2% and the SH is not recovering
toward the DhSp - 2%RH or, if the SH value rises above
the DhSp + 2%, or if the humidistat input is active, then
the unit will transition into full HGRH if (HSP+1°F)
< ZT
< (CSP+0.5?F) and the unit is operating at Stage 1 of
compressor cooling. The unit will perform the
following when transitioning into HGRH:
• Energize the supply fan, if not already ON, and
ramp the fan speed up to 100% of the application
airflow.
• Energize Stage 1 and Stage 2 of the compressor
operation with the reheat solenoid.
• Command the OA damper to minimum position.
If SH < DhSp - 5% or ZT < (HSP+0.5°F) or ZT > (CSP+1°
F) or ZT < (HSP+0.5°F) and the unit is operating at >
Stage 1 of compressor operation, then HGRH is
disabled. The unit will perform the following when
transitioning out of HGRH:
• Stage back to normal SZVAV Cooling:
• If ZT > (CSP+1°F), stage back to Cool 1, de-energize
the solenoid, release fan control and initialize DASP
to active DAT after a 3 minute delay.
• Stage back to normal control:
• If ZT < (HSP+0.5°F), leave dehumidification, de-
energize all compressor outputs and the reheat
solenoid immediately, and allow the unit to
transition into heat/cool mode based on ZT.
Initialize DASP based on active unit mode and
release Fan Control.
• If ZT > (CSP-0.5°F) and SH < DhSp - 5%, stage back
to Cool 1, de-energize the reheat solenoid, and
initialize DASP to active DAT after a 3 minute delay.
• If ZT < (CSP - 0.5°F) and SH < DhSp - 5%, leave
reheat, de-energize all compressors immediately,
and allow the unit to transition into heat/cool mode
based on ZT. Initialize DASP based on the active
unit mode.
If no request for active heating/cooling or fan operation
is present, the supply fan will remain energized at 100%
for 60 seconds after the compressor de-energizes.
Dehumidification Overrides
Sensible cooling or heating control overrides
dehumidification control. 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
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