4
COOLING MODE REFRIGERANT ROUTING
240H AND 300S UNITS
REHEAT
COIL
CIRCUIT 1
CONDENSER
COIL
CIRCUIT 2
CONDENSER
COIL
1
2
EXPANSION
VALVES
CHECK
VALVE
L14
REHEAT
VALVE
L30
REHEAT
VALVE
3
CHECK
VALVE
STAGE 1
EVAPORATOR
COIL
STAGE 2
EVAPORATOR
COIL
Note: Two refrigerant circuits are shown; both
circuits operate when there is a first-stage
thermostat demand (default).
FIGURE 39
WARNING
Disturbing the insulation in this product during
installation, maintenance, or repair will expose you
cancer. (Fiberglass wool is known to the State of
California to cause cancer.)
Fiberglass wool may also cause respiratory, skin
and eye irritation.
To reduce exposure to this substance or for further
information, consult material safety data sheets
available from address shown on unit nameplate or
contact your supervisor.
Check-Out
Test Hot gas re-heat operation using the following proce-
dure.
1 - Make sure reheat is wired as shown in wiring
section.
2 - Make sure unit is in local thermostat mode.
3 - Select Unit Controller Service - Test.
The blower, compressor 1 and compressor 2 (reheat)
should be operating. Reheat mode will appear on the
Unit Controller display.
4 - Deselect Unit Controller Service - Test.
Compressor 1 and 2 (reheat) should de-energize,,
blower should still be energized.
Default Reheat Operation
Reheat will operate as shown in table 40 once three con-
ditions 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 Control-
ler 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 man-
ual when using the transfer relay.
Four stages of cooling is available in zone sensor mode
on units with four compressors (240, 300S).
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.
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