Unit Start-up
96 RTHD-SVX02H-EN
Limit Conditions
UC800 will automatically limit certain operating parame-
ters during startup and run modes to maintain optimum
chiller performance and prevent nuisance diagnostic
trips. These limit conditions are noted in Table 30.
Table 30. Limit Conditions
Running -
Limited
The chiller, circuit, and compressor are
currently running, but the operation of
the chiller/compressor is being actively
limited by the controls. Further infor-
mation is provided by the sub-mode.
Condenser
Pressure Limit
The circuit is experiencing condenser pres-
sures at or near the condenser limit setting.
The compressor will be unloaded to prevent
exceeding the limits.
Low Evapora-
tor Refrigerant
Temperature
Inhibit
The circuit is experiencing saturated evaporator
temperatures at or near the Low Refrigerant
Temperature Cutout setting. The compressors
will be unloaded to prevent tripping.
Capacity Lim-
ited by Low
Liquid Level
The circuit is experiencing low refrigerant liquid
levels and the EXV is at or near full open. The
compressor will be unloaded to prevent trip-
ping.
Current Limit The compressor is running and its capacity is
being limited by high currents. The current
limit setting is 100% RLA (to avoid overcurrent
trips).
Phase Unbal-
ance Limit
The compressor is running and its capacity is
being limited by excessive phase current un-
balance.
Seasonal Unit Start-Up Procedure
1. Close all valves and re-install the drain plugs in the
evaporator and condenser heads.
2. Service the auxiliary equipment according to the
start-up/maintenance instructions provided by the
respective equipment manufacturers.
3. Vent and fill the cooling tower, if used, as well as
the condenser and piping. At this point, all air must
be removed from the system (including each pass).
Close the vents in the evaporator chilled water cir-
cuits.
4. Open all the valves in the evaporator chilled water
circuits.
5. If the evaporator was previously drained, vent and fill
the evaporator and chilled water circuit. When all air
is removed from the system (including each pass),
install the vent plugs in the evaporator water boxes.
D
CAUTION
Equipment Damage!
Ensure that the oil sump heaters have been operating
for a minimum of 24 hours before starting. Failure to do
so may result in equipment damage.
6. Check the adjustment and operation of each safety
and operating control.
7. Close all disconnect switches.
8. Refer to the sequence for daily unit startup for the
remainder of the seasonal startup.
9. For the heat recovery unit, if chiller can’t start up by
low system differential pressure at low condenser
inlet water temperature. you cna increase the param-
eter in TU: Unit start time (max to 60 seconds).
To Next Page
Loading...
Need help?
General
