Hi there -

Does anybody know how to make my expression work?

Problem:
I am trying to use two different chilled water loops per year. First is a regular "Chilled Water Loop" in service for summer and the second is a "Free Cooling Loop" in service for only winter time. Fan Coils connected to these loops are serving zones with high load density (e.g. Server, Electrical, etc.). Therefore I'd like to make an expression to be able to switch between those two loops in "HVAC System parameters/CHW Loop" based on outside drybulb temperature. I have found the variable (GLOBAL variable, variable in fortran is DBT) I have to call - just do not now how...

My expression:
if (#G("DBT") < 55)
then "Free Cooling Loop"
else "Chilled Water Loop"
endif

Thanks...
Norbert