Johnson Controls YORK YVAM 0350, Руководство по эксплуатации и техническому обслуживанию

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Some screens, displayed values, programmable setpoints, and manual controls exist for service
technician use only. They are only displayed when logged in at Service access level or higher. The
setpoints and parameters displayed on these screens are explained in detail in YORK YVAM Service
Manual (Form 160.88-M2) . These parameters affect chiller operation and must never be modified by
anyone other than a qualified service technician. The advanced diagnostics and troubleshooting
information for service technicians is included in YORK YVAM Service Manual (Form 160.88-M2) . Also
included in the Service manual are detailed descriptions of chiller features, such as capacity control,
refrigerant level control, variable geometry diffuser, and magnetic bearing controller.
The chiller operating program resides in the OptiView Control Center microboard. Software
versions (C.OPT.20.xx.yzz) are alphanumeric codes that represent the application, language
package, and revision levels as follows. Each time the controls portion or language section is
revised, the respective revision level increments.
• C: Commercial chiller
• OPT: OptiView
• 20: Chiller model (for example, YVAM)
• xx: Controls revision level (for example, 00, 01)
• y: Language package (0=English only, 1=NEMA, 2=CE, 3=NEMA/CE )
• zz: Language package revision level (for example, 00, 01)
Software upgrades must only be performed by a service technician.
System operation description
In operation, a liquid to be chilled (water or brine) flows through the evaporator tubes, where its
heat is transferred to low pressure liquid refrigerant sprayed over and pooled outside the tubes,
boiling the refrigerant. The chilled liquid is then piped to air conditioning or process terminal units,
absorbing heat. The warmed liquid is then returned to the chiller to complete the chilled liquid
circuit cycle.
The refrigerant vapor that is produced by the boiling action in the evaporator is drawn into the
suction of the compressor. The rotating impeller increases its pressure and temperature and
discharges the vapor into the condenser. Cooling air flowing through the condenser sections
absorbs heat from the refrigerant vapor and causes it to condense. The cooling air is always
at ambient conditions and requires correct installation for reliable operation. The condensed
refrigerant drains from the condenser into the evaporator liquid line and is controlled by the
condenser drain valve. This control valve causes the condensed liquid to stack in the lower portions
of the condensing sections creating the subcooling effect. The condenser drain valve meters the
flow of liquid refrigerant to the evaporator to complete the refrigerant circuit. The condenser
drain valve continually adjusts position as load changes to meet the changed mass flow rate of
refrigerant required to keep the system balanced. It does this by maintaining a constant subcooling
temperature, enough to maintain a liquid seal to the condenser liquid outlet.
Capacity control
The major components of a chiller are selected to handle the required refrigerant flow at full load
design conditions. However, most systems are required to deliver full load capacity for a relatively
short time while the unit is in operation. A means exists to modulate capacity for other loads.
The speed at which the compressor rotates establishes the pressure differential that the chiller can
operate against. This is referred to as lift. Speed must always be maintained above the minimum
necessary to create the lift required for the pressure difference between the condenser and
evaporator, regardless of load. Below that speed, gas surge occurs. That pressure difference is a
function of the LCHLT and the condensing temperature and the heat transfer between those two
systems and the refrigerant.
19 YVAM Control Center