York YCAZ33BA3, Руководство пользователя, Страница: 77 / 88

FORM 150.44-NM4
77
YORK INTERNATIONAL
DISCHARGE PRESSURE READ-OUT OPTION
The Discharge Pressure Read-out Option P/N 471-
01262-111 allows the user to obtain control panel dis-
plays of discharge pressure. Additionally, other displays
such as fault information will then hold relevant dis-
charge pressure information useful in diagnosing prob-
lems.
The Discharge Pressure Unloading feature also be-
comes usable when this option is installed (Page 35)
as well as fan cycling by discharge pressure.
Fan cycling by discharge pressure sometimes becomes
necessary, if ambient temperature cycling of fans
causes low suction pressure faults due to unusual op-
erating conditions or chiller location problems. Fan cy-
cling by discharge pressure only, allows higher dis-
charge pressures which in turn raises suction pressure
by permitting better operation of the thermal expan-
sion valve. To convert to discharge pressure cycling,
the micro panel must be programmed for DISCHARGE
PRESSURE FAN CONTROL (See Page 29). Fan cy-
cling will operate as indicated in Table 3.
The kit consists of discharge pressure transducers for
each system, wire harnesses, and associated mount-
ing hardware.
HIGH AMBIENT OPTION
The High Ambient Option consists of four kits, P/N’s
471-01262-111 and 475-05838-000. The option allows
operation of the chiller in ambients up to 115°F. Typi-
cally, standard operation is limited to 105°F. High am-
bient operation is accomplished by discharge pressure
unloading to assure that the chiller does not fault due
to the high pressure cut-out opening during high tem-
perature operation. A sun shield is also installed on the
control panel to prevent direct sunlight from overheat-
ing the control panel causing subsequent malfunction
of the electromechanical and electronic components
in the control panel. Additionally, actual discharge pres-
sure read-outs can now be obtained from the micro
panel.
Discharge Pressure unloading allows the microproces-
sor to unload a compressor when the discharge pres-
sure approaches a point nearing the discharge pres-
sure cut-out. This assures that the system does not
shut down completely if the cut-out were to open. See
page 35 for programming the unloading pressure.
Fan cycling by discharge pressure is also available
when this option is installed (See DISCHARGE PRES-
SURE READ-OUT OPTION, page 77), however it is of
little use in areas where ambients are generally high
and standard temperature control of the fans provides
good control and maximum efficiency.
LOCAL PRINTER OPTION
The Micro Panel is capable of supplying a printout of chiller
conditions or fault shutdown information at any given time.
This allows operator and service personnel to obtain data
and system status with the touch of the keypad. In addi-
tion to manual print selection, the micro panel will provide
an automatic printout whenever a fault occurs. An expla-
nation of the keypad use to obtain a printout is discussed
in the “PRINT” KEY Section on page 54.
YORK recommends the field tested WEIGH-TRONIX
IMP-24, Model 2600 printer. This is a compact low cost
printer that is ideal for service work and data logging.
Paper is in the form of a compact roll and is easily
handled compared to other printers using wider busi-
ness form style paper. The paper is 2.25" wide desk-
top calculator paper that can be easily and inexpen-
sively purchased at most stationery stores. Shown in
Fig. 30 and 31 is the WEIGH-TRONIX printer and a
typical sample printout.
TABLE 3 – FAN CYCLING
FAN CONTACTORS ON
1
OFF
2
1 REV
7M 320 PSIG 120 PSIG
(Opt. Low Ambient)
2 6M 340 PSIG 120 PSIG
1 FWD 5M 360 PSIG 140 PSIG
NOTES:
1. Fans will be activated when either system discharge pressure
exceeds the pressure indicated.
2. Fans will be deactivated when either system discharge pressure
drops below the pressure indicated, if the pressure on the other
system does not exceed the ON pressure.
23889A
FIG. 30 – WEIGH-TRONIX IMP-24 MODEL 2600
PRINTER