AAON LZ Series, Installation Operation & Maintenance

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Evaporator/Heat Exchangers
Evaporators are direct expansion type with an
electronic expansion valve to regulate
refrigerant. Normally no maintenance or
service work will be required.
Adjusting Refrigerant Charge
All AAON chillers are shipped with a full
factory charge. Periodically adjusting the
charge of a system may be required.
Adjusting the charge of a system in the field
must be based on determination of liquid sub-
cooling and evaporator superheat. On a
system with an expansion valve liquid sub-
cooling is more representative of the charge
than
evaporator superheat but both
measurements must be taken.
Before Charging
Refer to the unit nameplate as a reference
when determining the proper refrigerant
charge.
Unit being charged must be at or near full
load conditions before adjusting the charge.
Units equipped with hot gas bypass must
have the hot gas bypass valve closed to get
the proper charge.
After adding or removing charge the system
must be allowed to stabilize, typically 10-15
minutes,
before making any other
adjustments.
The type of unit and options determine the
ranges for liquid sub-cooling and evaporator
superheat. Refer to Table 12 when
determining the proper sub-cooling.
Prior to filter core service, a service
manifold MUST BE attached to in and
out pressure connections to assure no
pressure
exist during filter
maintenance. Non-compliance could
result in injury or violation of EPA
regulations.
WARNING
Polyolester (POE) and Polyvinylether
(PVE) oils are two types of lubricants
used in hydrofluorocarbon (HFC)
refrigeration systems. Refer to the
compressor label for the proper
compressor lubricant type.
CAUTION
The Clean Air Act of 1990 bans the
intentional venting of refrigerant
(CFC’s and HCFC’s) as of July 1,
1992. Approved methods of recovery,
recycling or reclaiming must be
followed. Fines and/or incarceration
may be levied for non-compliance.
CAUTION