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SGH/SCH036, 060, 120, 240
Check-Out
Test reheat operation using the following procedure.
1- Make sure reheat is wired as shown in wiring section.
2- Make sure unit is in local thermostat mode.
3- Use Unit Controller key pad to elect SERVICE > TEST
> DEHUMIDIFIER.
036, 060, 120 -
The blower and compressor (reheat) should be operating.
DEHUMIDIFIER 1 ON will be appear on the Unit Controller
display.
240 -
The blower, compressor 1, and compressor 2 (reheat)
should be operating. L14 and L30 LEDs on the Unit
Controller should also be ON, indicating the reheat valves
are energized. REHEAT MODE will be appear on the Unit
Controller display.
4- Press BACK on the Unit Controller display to stop the
testing mode.
Default Reheat Operation - 036 & 060
During reheat mode free cooling is locked out.
No Y1 demand but a call for dehumidification:
Compressor is operating, blower is on, and the reheat
valve is energized.
Y1 demand:
Compressor is operating, blower is on, and the reheat
valve is energized.
Y2 demand:
Compressor is operating, blower is on, and the reheat
valve is de-energized.
Default Reheat Operation - 120
TABLE 29
Reheat Operation - Two Cooling Stages - Default
T'stat and Humid
ity Demands
Operation
Reheat Only
Compressor 1 Reheat &
Blower Low Speed
Reheat & Y1
Compressor 1 Reheat &
Compressor 2 Cooling* &
Blower High Speed
Reheat & Y1 & Y2
Compressor 1 Cooling &
Compressor 2 Cooling** &
Blower High Speed
*If there is no reheat demand and outdoor air is suitable,
free cooling will operate.
**If there is no reheat demand and outdoor air is suitable,
free cooling and compressor 1 will operate.
Default Reheat Operation - 240
Reheat will operate as shown in table 30 once three
conditions are met:
1- Blower must be operating.
2- System must be in occupied mode.
3- System must NOT be operating in heating mode.
IMPORTANT - Free cooling does not operate during
reheat.
For other reheat control options, refer to the Unit Controller
manual.
Additional Cooling Stages
Units are shipped from the factory to provide two stages of
cooling.
Three stages of cooling is available in zone sensor mode.
Three stages of cooling is also available by installing a transfer
relay and a three-stage thermostat. Refer to the Main Control
Operation section in the Unit Controller manual when using the
transfer relay.
Additional Cooling Stages - 240
Four stages of cooling is available in zone sensor mode on
units with four compressors.
Compressors are not de-energized when unit operation
changes from cooling to reheat or from reheat to cooling.
Instead, L14 and L30 reheat valves are energized (reheat)
or de-energized (cooling).
NOTE - Another thermostat staging option is available
which allows both compressors to be energized during free
cooling. See Unit Controller manual for details.
