JOHNSON CONTROLS
FORM 150.72-EG6 (516)
54
For ground level installations, precautions should be taken to protect the unit from tam-
pering by or injury to unauthorized persons. Screws on access panels will prevent casual
tampering; however, further safety precautions, such as unit enclosure options, a fenced-
in enclosure, or locking devices on the panels may be advisable. Check local authorities
for safety regulations.
VARIABLE PRIMARY FLOW
Johnson Controls recommends a maximum 10% per minute flow rate of change, based
on design flow, for variable primary flow applications. Eight to 10 gallons per chiller ton
(8.6 to 10.8 liter per cooling kW) is recommended for the system liquid volume. Insuf-
ficient system volume and rapid flow changes can cause control problems or can even
cause chiller shutdowns. There are many other design issues to evaluate with variable
primary flow systems. Consult your Johnson Controls Sales Office for more information
about successfully applying YLAA chillers.
CHILLED LIQUID PIPING
The chilled liquid piping system should be laid out so that the circulating pump discharges
into the evaporator. The inlet and outlet evaporator liquid connections are given in
Unit
Dimensions on page 26
.
Hand stop valves are recommended for use in all lines to facilitate servicing. Drain con-
nections should be provided at all low points to permit complete drainage of the evapora-
tor and system piping. Additionally, a strainer (20 mesh) is recommended for use on the
INLET line to the evaporator.
Pressure gauge connections are recommended for installation in the inlet and outlet wa-
ter lines. Gauges are not furnished with the unit and are to be furnished by other suppliers.
The chilled liquid lines that are exposed to outdoor ambients should be wrapped with a
supplemental heater cable and covered with insulation. As an alternative, ethylene glycol
should be added to protect against freeze-up during low ambient periods.
A flow switch is available as an accessory on all units. The flow switch (or its equivalent)
must be installed in the leaving water piping of the evaporator and must not be used to
start and stop the unit.
Application Data (Cont'd)
Summary of Contents for YLAA
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