Technical data

7.7 Thermostatic Expansion Valve
YCWM/YCRM refrigerating circuits are provided
with a thermostatic expansion valve with an
external equaliser. Valves are calibrated at the
factory for a 5
o
C temperature rise.
To check the temperature rise:
Read the suction pressure using a pressure gauge
connected to the charging valve on suction side.
Using the pressure gauge temperature scale,
determine the saturated suction temperature Tsa
corresponding to this pressure.
Determine the effective suction temperature Tse
using a contact thermometer applied to the
evaporator gas outlet fitting.
Temperature rise S is given by:
S=Tse-Tsa
The temperature rise can be corrected using the
adjuster screw on the thermostatic expansion
valve. Turn the adjuster screw clockwise to
increase the temperature rise and
counterclockwise to reduce the temperature.
Turn the adjuster screw through a single revolution
and operate the unit for five minutes. Then check
the temperature rise again and correct as
necessary.
If the thermostatic expansion valve does not react
to temperature rise calibration, it is probably
malfunctioning and must be replaced. Valve
replacement must be performed by an authorised
York Service Centre.
7.8 Evaporator(s)
Check the heat exchanger water side for
cleanliness at regular intervals. This may be
accomplished by checking water side pressure
drop (refer to Section 9) or simply by checking the
fluid temperatures at heat exchanger inlet and
outlet and comparing them with evaporation
temperatures.
For effective heat exchange, the water outlet
temperature and the saturated evaporation
temperature should differ by 5 to 7 °C. A larger
difference indicates that the heat exchanger is
operating inefficiently, and is thus soiled.
If soiled, the heat exchanger must be chemically
cleaned by authorised York service personnel.
For other types of service (special maintenance,
heat exchanger replacement, etc.), contact an
authorised York Service Centre.
7.9 Condensers
Check the condenser water side for cleanliness at
regular intervals. This may be accomplished by
checking water side pressure drop (refer to
Section 9).
Soiling of the condenser results in increased
condensing pressure, which reduces efficiency
and increases current consumption and may
cause the high pressure switch to activate.
It is advisable to supply the condensers with anti-
algae and anti-lime treated water.
If soiled, the heat exchanger must be chemically
cleaned by authorised York service personnel.
For other types of service (special maintenance,
heat exchanger replacement, etc.), contact an
authorised York Service Centre.
035B40022-000 7-3