Dana,

What solution did you end up using to model the Multistack heat pump chiller
coupled to a vertical bore field in eQuest?

Any pointers would be greatly appreciated.

Thanks,
Steven

Steven Savich, LEED AP

Has anyone had any luck modeling a Multistack
(http://www.multistack.com/) unit in eQUEST?

We have a project that uses a Multistack unit to provide hot and chilled
water to a project and is coupled to a vertical bore field. eQUEST does
not have the capability to model system directly, so I have been trying
to look into other methods, all which are falling short. So far I have
tried:

* Using the "Loop-to-Loop Heat Pump" chiller; however, this
system does not work like the Multistack, as the Multistack does not
have internal heat exchange, has multiple compressor stages which are
all piped in parallel with the condenser water, and can only be
connected to a Lake/Well loop.

* Using a separate chilled water loop and hot water loop, each
of which are connected to a WLHP loop with a vertical bore HX. This
would be perfect, as I can put as many chillers and boilers on the loops
as there are stages in the Multistack; however, eQUEST does not have a
heat-pump boiler, so the boiler cannot be connected to the vertical bore
field.

* Using a dummy space/zone/system connected to a dummy heat
recovery chiller. The chiller would then reject heat to the hot water
loop that supplies the rest of the building. This would work, however
the chiller demand is driven by the cooling load of the dummy system and
it is impossible to create a dummy cooling load that would exactly match
the heating load required by the hot water loop.

* And finally, using a domestic hot water loop because the
boiler type can be set to "heat pump", however, the heat cannot be
rejected to a condenser water loop.

So I guess the question I am asking is has anyone either successfully
modeled the Multistack unit OR modeled a heat pump boiler?

Thanks in advance.

Dana Troy