Specifications

41
FORM 160.80-NOM1
YORK INTERNATIONAL
OIL EDUCTOR CIRCUIT
An oil eductor circuit is provided to properly manage
the amount of oil in the refrigerant charge. A small
amount of oil is normal in the refrigerant charge and
will be found in the evaporator. If not properly managed
the oil will accumulate and have adverse consequences
regarding chiller performance.
The oil eductor circuit consists of three refrigerant and
oil filter driers, two “jet pump” eductors and the inter-
connecting piping. Refer to Figures 21 and 22.
00089VIP
FIG. 21 – FILTER DRIERS AND OIL EDUCTOR
FILTER DRIERS
PRESSURE
RELEASE VALVE
EDUCTOR
MANIFOLD BLOCK
HIGH PRESSURE OIL AND REFRIGERANT
FROM OIL SEPARATOR
The eductors operate using the “jet pump” principle.
Discharge pressure gas and oil flows through a filter
dryer located at the bottom of the oil separator. YS
Chillers are supplied with a variable orifice arrangement.
The reduced pressure (pumping action) is created by
the velocity of the discharge pressure gas and oil flow-
ing through the orifice and nozzle. This creates a re-
duced pressure area that allows the oil-rich refrigerant
and oil to flow from the evaporator into the compressor.
Oil-rich refrigerant flows into the eductor block through
the filter drier from the evaporator. The oil rich refrig-
erant mixes with the discharge pressure gas and flows
into the compressor suction line.
A second eductor flows oil, which may have collected
in the evaporator trough through the second filter drier
located on the eductor block. This oil mixes with the
discharge gas in the eductor block and flows to the com-
pressor at port SC-5.
The filter driers should be changed annually or when
excessive amount of oil is indicated in the refrigerant
charge.
LIQUID REFRIGERANT CIRCUIT
Liquid refrigerant flows from the condenser into the
evaporator by differential pressure. Sub-cooled liquid
refrigerant flows out of the condenser into the liquid
line. A metering orifice is installed in the liquid line to
control the rate liquid refrigerant flows into the evapo-
rator. The orifice is selected based upon the operating
conditions of the chiller. Refer to Figure 23.
YS Chillers are supplied with a variable orifice arrange-
ment. In parallel with the metering orifice is a solenoid
valve and hand-throttling valve. The solenoid is ener-
gized open by the DIFFERENTIAL PRESSURE set
point that is field programmable from the panel. The
differential pressure between condensing pressure and
evaporating pressure is compared to the set point value.
When the differential pressure is at or less than the set-
point, the solenoid valve is energized open. The sole-
noid valve is de-energized closed when the differential
pressure is equal to or greater than the setpoint plus
10 PSIG. A hand-throttling valve is provided to adjust
the refrigerant flow rate through the solenoid valve to
match the system operating conditions.
Dual Service Chillers – Ice duty and comfort cooling
air conditioning applications will require the solenoid
valve to be energized open in the air conditioning mode
of operation since this represents the low differential
pressure mode of operation.
The differential pressure setpoint is field programmable
within the ranges specified in Table 5 for different re-
frigerants and EPROM version S.01F.17 and later. See
YORK Service Bulletin 160.47-M2 (SB18) for program-
ming instructions.
REFRIGERANT
DIFFERENTIAL
PRESSURE RANGE
R-22 25 - 150 PSID
R-134A 15 - 110 PSID
TABLE 5 – VARIABLE ORIFICE PRESSURE
DIFFERENTIAL SETPOINTS
A liquid line hand-isolation valve is located between the
condenser and the metering orifice plate. This valve, in
combination with the hand isolation valve between the
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