[Equest-users] Water-to-Water Heat Pump - is it possible?

[Chris Hadlock]

All,

I have a series of water-to-water heat pumps that are manifolded to allow
some circuits to operate in heating while others are operating in cooling,
with all circuits sharing a common condenser water loop.

I have created *two *2-pipe circulation loops (one for heating and one for
cooling), each connected to a different "Heat Pump" chiller. Both chillers
are connected to my common condenser loop. For the cooling loop, I have set
my snap temperature to an outdoor temperature of -20F (to ensure this loop
is always in cooling mode). Conversely, I have set an outdoor snap
temperature of 100F for my heating loop (to ensure this loop is always in
heating mode). On the air-side, I have modeled a fan coil (I have also
tried SZRH) and picked the 2-pipe cooling loop for the CHW loop and the
2-pipe heating loop as the HW loop.

The problem I seem to be running into is that eQuest will not allow 2
separate 2-pipe loops to operate independently and coincidentally over the
entire year (i.e. I can't get one chiller to provide hot water while at the
same time getting the other chiller to provide chilled water). I tried
different snap temperature options, like assigning a specific zone or using
a schedule loop operation (using type On/Off/TEMP) whereby I set the
cooling chiller to 1 for cooling and zero for heating...and vice-versa for
the heating chiller...to no avail.

I previously had the model configured so that the chillers provide both
heating and cooling (as in Loop-to-Loop Heat Pump)...by this is not the way
the heat pumps are actually being operated.

I would appreciate any suggestions/help as I've spent a lot of time trying
just about everything I can think of.

Thanks,
Chris
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