AAON CL SERIES, Установка, эксплуатация и обслуживание

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Special Low Ambient Charging Instructions:
For units equipped with low ambient refrigerant
flood back option
being charged in the summer
when the ambient temperature is warm :
If the ambient is
above 70°F, charge to
approximately 1-2°F of sub-cooling measured at
the inlet to the expansion valve. Once enough
charge has been added to get the evaporator
superheat and sub-cooling values to the correct
setting more charge must be added. Add the
calculated charge amount to flood the condenser
coil. The additional charge is required for the
system when running in cold ambient conditions.
Contact Technical Support for this charge amount.
AAON Technical Support
Ph: (918) 382-6450
techsupport@AAON.com
For units equipped with low ambient refrigerant
flood back option
being charged in the winter
when the ambient temperature is cold :
1. If the ambient is below 70°F, charge to
approximately 1-2°F of sub-cooling
measured at the inlet to the expansion valve.
Once enough charge has been added to get
the evaporator superheat and sub-cooling
values to the correct setting, more charge may
need to be added. If the ambient temperature
is 0°F, no more charge is required. If the
ambient temperature is between 0°F and
70°F, multiply the charge amount needed at
70°F ambient (call AAON Technical Support
to get this value) by the percentage below that
corresponds to the ambient temperature. The
result is the additional charge that must be
added to the circuit.
Table 3 - % Charge to Flood Condenser Coil for
Ambient Below 70°F
Condenser
Ambient
Temperature °F % of flooded charge
needed
at 70°F
ambient
60 60%
50 37%
40 24%
30 15%
20 8%
0 0%
2. Check the unit for proper operation once
the ambient temperature is above 80°F.
Low Ambient Operation:
The AAON low ambient (condenser flood-back)
system is used to operate a refrigerant system
below 35°F outside air temperature. As the
ambient temperature drops, the condenser
becomes more effective therefore lowering the
head pressure. When the head pressure gets too
low, there will be insufficient pressure to operate
the expansion valve properly. During low
ambient temperatures, it is difficult to start a
system because the refrigerant will migrate to the
cold part of the system (condenser) and make it
difficult for refrigerant to flow.
The AAON low ambient system maintains normal
head pressure during periods of low ambient by
restricting liquid flow from the condenser to the
receiver, and at the same time bypassing hot gas
around the condenser to the inlet of the receiver.
This backs liquid refrigerant up into the condenser
reducing its capacity that in turn increases the
condensing pressure. At the same time the
bypassed hot gas raises liquid pressure in the
receiver, allowing the system to operate properly.
There are different types of low ambient control
used. The following describe the different
systems. Inspect the unit to determine the system
used.