Product Manual PM WSC/WDC 57
To obtain 55°F (12.8°C) entering condenser water
temperature with a tower selected to produce 85°F
(29.4°C) water temperature at design ambient air
temperatures, cooling tower fans must continue to
operate at 100% capacity at low wet bulb
temperatures. As chillers are selected for lower kW
per ton, the cooling tower fan motor power becomes
a higher percentage of the peak load chiller power.
On the other hand, the low condenser water
temperatures may be easy to achieve in mild climates
with low wet bulb temperatures.
Even with tower fan control, some form of water flow
control such as tower bypass is recommended.
Oil Coolers
WSC-048/050 and WDC-048/050 units are equipped with internal self-contained refrigerant-cooled oil coolers
and require no field piping for the coolers.
WSC 063, 079, 087, 100 and 126 single compressor units have a factory mounted water-cooled oil cooler,
temperature controlled water regulating valve and solenoid valve, all as standard. Connection location is
inboard of the compressor location. Accessories must be installed as shown in the following piping diagrams.
WDC 063, 079, 087, 100 and 126 dual compressor units are equipped as above but the water piping for the two
oil coolers cooling is factory piped to a common connection at the tube sheet.
Field water piping to the inlet and outlet connections must be installed according to good piping practices and
should include stop valves to isolate the cooler for servicing. A 1" minimum cleanable filter (40 mesh maximum),
a solenoid stop valve wired in accordance with the field connection control diagram (also available as a factory
installed option,), and drain valve or plug should also be field installed. The water supply for the oil cooler may
be either from the chilled water circuit (preferred and recommended) or from an independent source such as city
water. When using chilled water it is important that the water pressure drop through the oil cooler be less than
the drop across the evaporator or insufficient oil cooler flow will result. This is normally no problem except on
single pass evaporators in which case the oil cooler water should be piped across the chilled water pump to
provide the maximum possible head and flow.
The water flow through the oil cooler will be adjusted by the regulating valve so that the temperature of oil
supplied to the compressor bearings (leaving the oil cooler) is between 80°F and 110°F (27°C and 43°C).
When supplied with city water, the oil piping should discharge through a trap into an open drain to prevent
draining the cooler by siphoning. The city water may also be used for cooling tower makeup by discharging it
into the tower sump from a point above the highest possible water level.
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