IM 1044-2
Centrifugal Chillers
9
Water Piping
Water Pumps
Avoid the use of 3600/3000-rpm (two-pole motor) pump motors. It is not uncommon to find that these pumps
operate with objectionable noise and vibration.
It is also possible to build up a frequency beat due to the slight difference in the operating rpm of the pump
motor and the
Daikin
centrifugal motor.
Daikin
encourages the use of 1750/1460 rpm (four-pole) pump motors.
Vessel Drains at Start-up
Unit vessels are drained of water in the factory and are shipped with the drain plugs in the heads removed and
stored in the control panel or with open ball valves in the drain hole. Be sure to replace plugs or close the valves
prior to filling the vessel with fluid.
Evaporator and Condenser Water Piping
All evaporators and condensers come standard with Victaulic AWWA C-606
groove nozzles (also suitable for welding), or optional flange connections. The
installing contractor must provide matching mechanical connections or
transitions of the size and type required.
Victaulic connections are AWWA C-606 on 14-inch and larger sizes. Field
supply transitions if Victaulic brand AGS® (Advanced Groove System) type
grooves are used on the field piping.
Note
: Do not use PVC piping.
The tower connections on heat recovery units are always the inboard pair of
connections. In the figure to the right, the condenser connections are “left-hand”
when viewed from the front of the unit (Unit Control Panel and Interface Panel
side), so in this case, the right-hand condenser connections would be for the
tower. If the condenser connections were on the other end (“right-hand”), the
tower connections would be the left-hand pair of connections.
Note: Certain WSC units with a 2-pass configuration and copper tubing may
have an “over/under” connection configuration on the evaporator, rather than the side-by-side configuration
shown here. Consult Certified Drawings for exact configuration and dimensions.
Important Note on Welding
If welding is to be performed on the mechanical or flange connections, remove the solid-state temperature sensor
and thermostat bulbs from the wells to prevent damage to those components. Also properly ground the unit or
severe damage to the MicroTech II unit controller can occur.
Note:
ASME certification will be revoked if welding is performed on a vessel shell or tube sheet.
Water pressure gauge connection taps and gauges must be provided in the field piping at the inlet and outlet
connections of both vessels for measuring the water pressure drops. The pressure drops and flow rates for the
various evaporators and condensers are job specific and the original job documentation can be consulted for this
information. Refer to the nameplate on the vessel shell for identification.
Be sure that water inlet and outlet connections match certified drawings and stenciled nozzle markings. The
condenser is connected with the coolest water entering at the bottom to maximize subcooling.
CAUTION
When common piping is used for both heating and cooling modes, care must be taken to provide that water flowing through
the evaporator cannot exceed 110°F which can cause the relief valve to discharge refrigerant or damage controls.
The piping must be supported to eliminate weight and strain on the fittings and connections. Piping must also be
adequately insulated. A cleanable perforated basket strainer with 0.125-in perforations and 40 % open area must
be installed in the evaporator water inlet line. Sufficient shutoff valves must be installed to permit draining the
water from the evaporator or condenser without draining the complete system.
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