Operating Sequence; Water Regulating Valve - Carrier Omnizone 50XCW06 Installation Start-Up And Operatig Instructions

Operating Sequence

All units require the addition of a thermostat accessory package to
complete the control circuit. The sequence of operation may vary
depending on which package is selected.
ROOM-MOUNTED THERMOSTAT
These units use an electronic thermostat mounted in the condi-
tioned space.
FAN CIRCULATION
The indoor-fan motor is energized through G on the thermostat
and the indoor-fan contactor is energized. This starts the indoor-
fan motor (IFM). The fan will operate to provide continuous air
circulation.
COOLING
The indoor fan will operate continuously or when the compressor
runs, depending on the setting of the thermostat fan selector
switch. When the thermostat closes on a call for cooling (Y1) the
compressor contactor closes to start the first stage compressor.
If additional cooling demand is required, the second stage (Y2) on
50XCW12-24 units will close and will then start the second-stage
compressor. When the thermostat is satisfied, the second-stage
compressor will stop first, and then the first-stage compressor will
stop when cooling demand is satisfied.
HEATING (IF EQUIPPED WITH HOT WATER OR STEAM
COIL)
When thermostat closes on a call for heating (W1), it will engage
beginning stages of heating.
ECONOMIZER OPERATION
Economizer operation is enabled if entering water set point is
above water supply temperature and there is a call for first stage
cooling (Y1 closes at the thermostat). If the water supply tempera-
ture is above the set point then economizer operation will be dis-
abled and the first stage cooling will enable compressor operation.
Economizer control valve will be modulated open or closed to
maintain a supply-air temperature between 50 and 55°F. The
economizer valve will be fully open when the supply-air tempera-
ture exceeds 55°F. On call for second stage cooling if economizer
is enabled, first-stage compressors will be enabled if entering-
water temperature is still below set point.
To adjust the changeover set point, press and hold the MENU but-
ton until the display flashes "SP" (about 2 seconds). Press MENU
again to display the existing set point value. Use the up or down
arrows to change the set point value and then press MENU again
to save the new value.
2-SPEED FAN OPERATION SEQUENCE
On the VFD the following parameters must be set on each unit. To
change the parameters:
1. Press MENU.
2. Select Parameters.
3. Press ENTER.
4. Select sub-group (first two digits of the parameters).
5. Press SEL.
6. Select parameter.
7. Press EDIT.
8. Select the new value. (See Table 10.)
9. Press SAVE.
10. Select any other parameters of the group to change and go to
Step 7.
11. When complete, press EXIT.
12. Select any other parameter groups to change and go to Step 5.
13. When complete, Press EXIT.
14. Press EXIT until the status menu is visible (HZ, PSI, PSI).
Table 10 — VFD Parameters
PARAMETER
PARAMETER FUNCTION
INDEX
9906 Motor Nominal Voltage
9907 Motor Nominal Current
9908 Motor Nominal Speed
9909 Motor Nominal Power
On the VFD, the following parameters must be loaded from the
IFM-VFD configuration keypad. The parameter list is provided
should the keypad be damaged and the points loaded manually.
(See Table 11.) To download parameters from the configuration
keypad:
1. Press MENU.
2. Select PAR Backup.
3. Press SEL.
4. Select Download to Drive ALL.
5. Press SEL.
6. When download is complete press SEL.
Table 11 — IFM - VFD Parameters
PARAMETER
PARAMETER FUNCTION
INDEX
9902 Application Macro
1101 Keypad Ref Sel
1102 EXT 1 - EXT 2 SEL
1106 REF2 Select
1107 REF2 Minimum
1201 Constant Speed Select
1202 Const Speed 1
1601 Run Enable
1608 Start Enable
1611 View
Should it be necessary to upload data to the configuration keypad:
1. Press MENU.
2. Select PAR Backup.
3. Press SEL.
4. Select Upload to Panel.
5. Press SEL.
6. When download is complete press SEL.
ALL UNITS
The control circuit incorporates a current sensing lockout relay
(Cycle-LOC™ device) that locks off the compressor(s) for 5 min-
utes when any safety device is activated (low or high pressure
switches, or compressor internal overload). If any compressor
safety device opens, the compressor will stop. High and low-pres-
sure switches and compressor motor overload protectors will reset
automatically when the condition which caused the device to trip
has dropped below the reset condition. To reset the Cycle-LOC
control device, manually turn the control power OFF, then back
ON.

Water Regulating Valve

The water regulating valve is a direct acting 2-way pressure actu-
ating water regulating valve located on the inlet of the condenser
that modulates water flow to control discharge pressure of the
compressors above a minimum head pressure. This valve allows
the unit to operate with entering water temperatures as low as
40°F.
34
CHANGES FROM STANDARD
MACRO
Set to Unit Voltage (208/230V =
230V, 460V, or 575V)
Motor FLA
Motor Nameplate
Motor HP
CHANGES FROM STANDARD
MACRO
1 (HVAC Default)
2 - REF2 (%)
7 - EXT 2
2 - AI2
67%
-2 - DI2(INV)
60 Hz
1 - DI1
0 - Not Sel
Long View