York YVAG012 Operation & Maintenance Manual page 16

should be wrapped with supplemental heater cable and
insulated to protect against freeze-up during low
ambient periods, and to prevent formation of
condensation on lines in warm humid locations. Vent
valves and drain valves do not need heat isolation for
the convenience of maintenance
k) The inlet minimal pressure of water pump shall
reach 20kPa to avoid cavitation noise and damage of
water pump due to cavitation.
l) It is recommended that a suitably sized by-pass
and valve arrangement shall be installed to allow
flushing of the pipework system. The by-pass can be
used during maintenance to isolate the cooler without
disrupting flow to other units.
m) Drain connections should be provided at all low
points to permit complete drainage of the cooler and
system water piping during low ambient temperature
period and the unit would not be used with a long time.
Unit power should be left switched on to provide the
freeze protection function unless the liquid systems
have been drained. Also unit power should be left
switched off to avoid unit failure by auto starting for
the freeze protection function while the liquid systems
have been drained.
n) The fan coil in the water system shall be equipped
with a three-way valve or a by-pass valve to make the
water system circulate fluently during the period when
anti-freezing water pump is operating in winter.
Piping specification
Specification of galvanized steel pipes
Outer diameters of galvanized steel
pipes (mm)
Specification of PP-R pipes
Outer diameters of PP-R pipes (mm)
JOHNSON CONTROLS
Cooke Industries - Phone: +64 9 579 2185
o) For module application, a place for thermometer
sensor shall be retained on the main outlet pipe of the
water system so that the leaving water temperature
sensor can be installed.
p) A chilled water flow switch is already installed in
the leaving water piping of the cooler. If the units are
modularized, it is recommended to install another flow
switch in main liquid leaving pipe.
G3/4 G1 G1-1/4
DN20 DN25 DN32
27 34 42
D25 D32 D40
25 32 40
TABLE 4 – PIPE LINES SPECIFICATIONS
Email: sales@cookeindustries.co.nz
FORM NO.: 6U5M-A11M-NB-EN
The Flow Switch MUST NOT be used
to start and stop the unit (i.e. starting
and stopping the chilled water pump). It
is intended only as a safety switch.
Quality of the chilled water should
comply with the requirement in chilled
water requirement in SECTION 5. No
air will be permitted in water system.
Thread specification
G1-1/2 G2 G2-1/2
DN40 DN50 DN65
48 60 76
D50 D63 D75
50 63 75
Web: www.cookeindustries.co.nz
G3 G4
DN80 DN100
89 114
D90 D110
90 110
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