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© 2015 Heatcraft Refrigeration Products, LLC
Check Out and Start Up
1. After the installation has been completed, the following points should be
covered before the system is placed in operation:
2. Check all electrical and refrigerant connections.
Be sure they are all tight.
3. Check compressor mounting fasteners for tightness.
4. Check microprocessor for operation of high and low pressure controls,
pressure regulating valves, oil pressure safety controls, and all other safety
controls, and adjust if necessary.
5. Wiring diagrams, instruction bulletins, etc., attached to the
condensing units should be read and filed for future reference.
6. All fan motors should be checked for proper rotation. Fan
motor mounts should be carefully checked for tightness and
proper alignment.
7. Electric evaporator fan motors should
be temporarily wired for continuous operation until
the room temperature has stabilized.
8. 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.
9. 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.
10. 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
within lower sight glass range.
11. Make sure all Schrader valve caps are in place and tight.
12. Make sure ALL service valves are properly back-seated and tighten
valve packing if necessary.
Operational Check Out
After the system has been charged and has operated for at least two hours at normal
operating conditions without any indication of malfunction, it should be allowed to
operate overnight on automatic controls. Then a thorough recheck of the entire system
operation should be made as follows:
1. Check compressor discharge and suction pressures. If not within system
design limits, determine why and take corrective action.
2. Check liquid line sight glass and expansion valve operation. If there are
indications that more refrigerant is required, leak test all connections and
system components and repair any leaks before adding refrigerant.
3. Observe oil level in compressor crankcase sight glass. Add oil as
within lower sight glass range.
4. Thermostatic expansion valves must be checked for proper superheat settings.
Feeler bulbs must be in positive contact with the suction line and should
be insulated. Valves set at high superheat will lower refrigeration capacity. Low
superheat promotes liquid slugging and compressor bearing washout.
5. Using suitable instruments, carefully check line voltage and amperage at the
compressor terminals. Voltage must be within 10% of that indicated on the
condensing unit nameplate. If high or low voltage is indicated, notify the power
company. If amperage draw is excessive, immediately determine the cause
and take corrective action. On three phase motor compressors,
check to see that a balanced load is drawn by each phase.
6. The maximum approved settings for high pressure controls on
our air cooled condensing equipment is 425 psig. On air cooled
systems, check as follows:
Disconnect the fan motors or block the condenser inlet air. Watch
high pressure gauge for cutout point. Recheck all safety and
operating controls for proper operation and adjust if necessary.
7. Check drain pan for proper drainage.
8. Check winter head pressure controls for pressure setting.
9. Check oil sump heater operation
10. Install instruction card and control system diagram for use of building manager
or owner.
System Balancing - Compressor Superheat
IMPORTANT:
In order to obtain the maximum capacity from a system, and to ensure
trouble-free operation, it is necessary to balance each and every system.
This is extremely important with any refrigeration system.
The critical value which must be checked is suction superheat.
Suction superheat should be checked
at the compressor
as follows:
1. Measure the suction pressure at the suction service valve of the compressor
and determine the saturation temperature corresponding to this pressure from
a “Temperature-Pressure” chart.
2. Measure the suction temperature of the suction line about one foot back from
the compressor using an accurate thermometer.
3. Subtract the saturated temperature from the actual suction line temperature.
The difference is superheat.
Too low a suction superheat can result in liquid being returned to the compressor. This
will cause dilution of the oil and eventual failure of the bearings.
Too high a suction superheat will result in excessive discharge temperatures which
cause a break down of the oil and results in wear, and damage.
It should also be remembered that the system capacity decreases as the suction
superheat increases. For maximum system capacity, suction superheat should be
kept as low as is practical. We recommend that the superheat
at the compressor
be
between 5˚F and 15˚F.
If adjustments to the suction superheat need to be made, the expansion valve at the
evaporator should be adjusted.
CAUTION:
Check phase rotation with phase meter prior to first start.
Warranty will be denied if damage is a result of reverse rotation. 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 required.
NOTE:
All adjustable controls and valves must be field adjusted to meet
desired operation. There are no factory preset controls or valve adjustments.
This includes low pressure, high pressure, adjustable head pressure systems
and expansion valves.
