I am modeling a bypass system with a constant volume fan and zone
dampers (no reheat) in the space. This seems like it would fall under
the CBVAV system, except that my units have DX coils instead of CHW.
eQuest will not allow DX instead of CHW, so I'm wondering at a way to
approximate this. Set the chiller performance curve to DX and assign
the CHW pump energy to another, non-tariffed, meter? Use a PVVT system
instead?
Any help is appreciated.
-Beka
Hi Beka,
If you use a Variable Volume (VAV) system to model a Constant Volume (CV)
system, you will really create problems for yourself. You state, and your
system diagram confirms, that you have a constant volume fan and zone
dampers, no reheat. I would probably use the PSZ system as the path of least
resistance.
With PSZ you have to use a Control Zone, which is like the zone where the
thermostat is, so try to use a system per zone wherever possible. If you
have multiple thermal zones served by the same Control Zone the hours
outside the throttling range can be tricky. Another trick when you don't
want reheat to make sure your main heating coil is activated by using
Heat-Set-T. You can click on it and read the online help.
Best,
Carol Gardner PE