OMM 1008-1
13
Low Condenser Water Temperature Operation
When the ambient wet bulb temperature is lower than design, the entering condenser water temperature can
be allowed to fall to improve chiller performance. This is especially true of an advanced design such as the
McQuay Magnitude chiller that features variable compressor speed.
It is an engineering fact that as the compressor discharge pressure is reduced, the amount of power to pump
a given amount of gas also is reduced. The reduction can result in significant energy savings.
However, as with most centrifugal chiller applications, a tower bypass valve must be installed and must be
controlled by the chiller MicroTech II controller. Figure 3 illustrates two temperature actuated tower
bypass arrangements. The “Cold Weather” scheme provides better startup under cold ambient air
temperature conditions. The check valve may be required to prevent entraining air at the pump inlet.
Figure 3, Bypass, Mild Weather Operation
Bypass, Cold Weather Operation
