I am modeling the water side economizer by eQuest. When the outdoor
temperature is lower than the pre-set temperature, the chiller will stop
operating and heat exchanger will substitute the chiller to cool down
the chilled water. The eQuest simulation program, however, seems that
the definition is differ from our approach. From the help section of
eQuest, WS Economizer effectiveness is defined as "The coil design
effectiveness for the economizer coil, between the condenser water loop
and the mixed-air temperature". If the one defined by eQuest is same as
that defined by me, shouldn't the effectiveness be the effectiveness
between the condenser water loop and the outdoor air temperature? And as
heat exchanger does not involved in the eQuest WS Economizer, does it
mean that eQuest's WS Economizer cannot model our system? If yes, is it
possible to simulate this system through other ways? If no, could anyone
advise how to input this system? Many thanks.

Best regards,

Jonathan Mak, LEED AP