Heatcraft Refrigeration Products 25001401, Инструкция по установке и эксплуатации

Страница: 33 / 36

33
EVAPORATORS
All evaporator units should be checked once a month or more often
for proper defrosting because the amount and pattern of frosting can
vary greatly. It is dependent on the coil temperature, the temperature
of the room, the type of product being stored, how often new product
is brought into the room and the percentage of time the door to the
room is open. It may be necessary to periodically change the number
of defrost cycles or adjust the duration of defrost.
CONDENSING UNITS / EVAPORATORS
Under normal usage conditions, maintenance should cover the
following items at least once every 6 months:
1. Check and tighten ALL electrical connections
2. Check all wiring and insulators
3. Check contactors for proper operation and for
worn contact points
Check-Out & Start-Up
After the installation has been completed, the following points should
be covered before the system is placed in operation:
(a) Check all electrical and refrigerant connections.
Be sure they are all correct and tight.
(b) Check voltage taps on transformer at the evaporators.
The transformer is shipped wired to 240 voltage tap/
connection. If your supply voltage is 208 volt systems,
change to 208 voltage tap.
(c) Check high and low pressure controls, pressure
regulating valves, oil pressure safety controls, and all
other safety controls and adjust them, if necessary.
(d) On freezers only, check the low pressure switch setting.
It must be set to 0 PSIG cut out, 10 PSIG cut in, to allow
start and operation, especially in cold ambients.
(e) Liquid line should always be insulated.
(f) Wiring diagrams, instruction bulletins, etc. attached to
the condensing units should be read and filed for future
reference.
(g) All fan motors on air cooled condensers, evaporators,
etc. should be checked for proper rotation. Fan motor
mounts should be carefully checked for tightness and
proper alignment.
(h) Observe system pressures during charging and initial
operation. Do not add oil while the system is short of
refrigerant unless oil level is dangerously low.
Preventive Maintenance
4. Check all fan motors. Tighten motor mount bolts
and nuts and tighten fan set screws
5. Clean the condenser coil surface
6. Check the refrigerant and oil level in the system
7. Check the operation of the control system. Make
certain all safety controls are operating properly
8. Check that all defrost controls are functioning
properly
9. Clean the evaporator coil surface
10. Clean the drain pan and check the drain pan and
drain line for proper drainage
11. Check the drain line heater for proper operation,
cuts and abrasions
12. Check and tighten all flare connections
(i) Continue charging until system has sufficient refrigerant
for proper operation. Do not overcharge. Remember that
bubbles in a sight glass may be caused by a restriction
as well as a shortage of refrigerant.
(j) Do not leave unit unattended until the system has
reached normal operating conditions and the oil charge
has been properly adjusted to maintain the oil level at
the center of the sight glass.
(k) At initial start-up, the system may cycle off at 2 minutes
and display a low superheat error, then restart itself. This
cycle may be repeated a few times. Do not shut the
system off. Let the system run, as it may take a few
cycles for the electric expansion valve to attain the
correct setting for the desired superheat.
CAUTION: Extreme care must be taken in starting compressors for the
first time after system charging. At this time, all of the oil and most of the
refrigerant might be in the compressor creating a condition which could
cause compressor damage due to slugging. Activating the crankcase heater
for 24 hours prior to start-up is recommended. If no crankcase heater is
present, then directing a 500 watt heat lamp or other safe heat source on
the lower shell of the compressor for approximately thirty minutes will be
beneficial in eliminating this condition which might never reoccur.