Schreiber Chillers 15medWC - Manual (Page 23)

CHILLER SYSTEMS:
CHILLED WATER CIRCUIT
Cryo Compressor Pump
The pump Cryo compressor pump is a positive displacement pump capable of delivering 4 GPM.
This flow rate is constant under all conditions. The discharge pressure will vary according to the
length of pipe and the number of fittings in the pipe system. A T-handle pressure relief valve
allows adjustment of the discharge pressure. It should be set to no more than 50 psi
The Cryo compressor pump motor is EXTERNALLY overload protected. In the event of
overload, pump will shut down, and a “CIRCUIT #2 FLOW” alarm will be generated. The
overload will automatically reset, however, the controller flow alarm must be reset.
GCHE/GAHE Pump
The GCHE pump is a 1 HP centrifugal pump. There is a ball valve that short circuits the
discharge and return valve to allow for flow adjustment. The ball valve should be opened so that
there is no more than 35 psi difference between the discharge and return pressure readings for the
GCHE pump. If the pressure is to high, the valve must be opened to divert flow. If it is too low
and the not enough water is going to the GCHE, it must be closed. In order to properly set the
valve position, the adjustments should be made when during a scan when the MR equipment is
putting the full heat load into the chilled water system.
All of the bypassed water returns to the reservoir through the evaporators. The return line water
is diverted to both evaporators.
The pump motor is INTERNALLY overload protected. In the case of an overload the pump will
shut off. The controller will show a “CIRCUIT #1 Flow” error. When the alarm is reset, the
pump will restart if the motor has cooled down to the point where the overload is closed. If the
overload is still open, the controller will try to restart the pump, but will generate another flow
error after the pump start up time delay.
Any time the flow error is reset, the compressors will turn on automatically if cooling is required.
A wye strainer is installed in the return line to prevent the evaporators from fouling. If there is a
noticeable drop in flow, the wye strainer may be full. It can be cleaned by opening the cleanout
valve on the front of the chiller. This must be done while the pump is running. A small bucket
should be place under the valve to catch debris and water that will l=come out of the valve. The
valve only needs to be open for a few seconds.