Carrier 09DK054-094 - Manual (Page 20)

2. Install Fan Cycle Pressure Switches and Clamps — Four
FCPSs should be used. Locate holes, valve core assem­
blies, and FCPSs 1, 2, 3, and 4 at the specified locations.
See Fig. 9. Insert valve cores into valve core bodies by
threading into place and tightening to 1.5 to 3 in.-lb (169.5
to 339 mN-m). The additional two FCPSs and valve core
assemblies are provided with the accessory fan control kit.
Cut the 3/8-in. field-supplied FCPS conduit to fit between
each FCPS location and the junction box on the unit. See
Fig. 13 for typical conduit installation. Feed FCPS wires
through each conduit and secure at the switch using each
conduit connector. See Fig. 15. Secure the conduit at the
junction box with 3/8-in. field-supplied conduit connectors
Wire the FCPSs according to Fig. 16 and 20. Note that
FCPS2 and 4 and FCPSl and 3 are wired in parallel. Fans
3 and 4 are shared by two different refrigeration circuits;
the fan switches on if either circuit requires it. Clamp all
lines to brackets supplied on the unit.
SAE — Society of Automotive Engineers
Fig. 15 — Fan Cycle Pressure Switch
REFRIGERANT LINE SIZING - Sizing depends on length
of lines between various sections of the refrigerant system.
See Fig. 10 for coil connection details. Consider the amount
of liquid lift and drop in the system as well as proper com­
pressor oil return. See Liquid Lift section for more infor­
mation. Consult Carrier System Design Manual, Part 3, or
Carrier E20-II Refrigerant Piping Computer Program for proper
piping sizes and design.
LIQUID SHUTOFF VALVE AND SIGHT GLASS - A
shutoff valve is not supplied with 09DK condensers. It is
strongly recommended that a full line size liquid shutoff
valve be field supplied near condenser to allow for servic­
ing parts of the refrigerant circuit. A field-supplied moisture-
indicating sight glass is recommended for use in charging
and servicing the system. Refer to Fig 8.
PRESSURE RELIEF - The ASHRAE Standard 15, Safety
Code for Mechanical Refrigeration states: “Every refriger­
ating system shall be protected by a pressure relief device
or some other means designed to safely relieve pressure due
to fire or other abnormal conditions.” Since 09DK con­
densers do not have pressure relief devices, one must be
field supplied and installed just before the liquid line serv­
ice valve. (See Fig. 8.) When the split coil is used with
multiple systems, each system must have its own pressure
relief.
REFRIGERANT RECEIVER — A refrigerant receiver is
not furnished with 09DK condensers and is not recom­
mended for normal applications as its use will be detrimen­
tal to the desired effects of subcooling. However, if a par­
ticular application requires a receiver to increase refrigerant
holding capacity of the condenser, a receiver can be used.
Recommended receiver and valve installation and piping are
shown in Fig. 28. When a receiver is to be used year-
round, it should be installed indoors.
Procedure for Using the Refrigerant Receiver — (Fig. 281
1. During normal operation — Valve A is open and valves
B and C are closed. Receiver is isolated from the
system.
2. For servicing — Valves A and C are closed and valve B
is open. Run unit until all the refrigerant is in the re­
ceiver and then close valve B. Unit is now ready for ser­
vicing.
3. To resume operation — Leave valve A closed and open
valves B and C. Run unit until the stored refrigerant is
drawn into the system. To completely remove the re­
frigerant from the receiver, throttle valve B while noting
condition of refrigerant in the liquid line sight glass; also,
watch the suction pressure. A sudden surge of bubbles
in the sight glass and a rapid decrease in suction pres­
sure indicate that all the refrigerant has been withdrawn
from the receiver Immediately close valves B and C
and then open valve A. The unit should now be ready
for normal operation, with the receiver isolated from the
system. The system should be charged to a clear sight
glass when under normal operation.
LIQUID LIFT — Amount of liquid lift available before re­
frigerant flashing occurs depends on amount of liquid sub­
cooling in the system
All 09DK condensers have positive subcooling when ap­
plied with optimum charge. With subcooling, it is possible
to overcome an appreciable pressure drop and/or static head
(due to elevation of the liquid metering device above the
condenser).
When 09DK condensers are applied with minimum charge,
they do not provide positive subcooling. If subcooling is
required, it must be obtained by external means such as a
liquid suction interchanger.
The average amount of liquid lift available is shown in
Table 3 for refrigerants R-22, R-502, and R-134A. Avail­
able subcooling is greatly reduced when R-12 and R-500
are used in these units It is recommended that the evapo­
rator be at the same level as the condenser, or lower.
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