[Equest-users] Ground Loop HX

[Ron Pecarina]

I have yet to hear a response on this one, so I'll try again.

I am trying to model a ground source heat pump system with a ground source
HX.  The actual system includes the primary loop pump, Taco Loadmatch
circulators for the individual heat pumps (secondary) and a pump for the
well field.  The well field pump flow is 50% of the HP loop flow.  The
initial modeling results in full flow from the HP loop through the well
field which keeps the loop temperature low (typically 40s-50sF).  The
controls for the well field pump is to run the pump when the loop
temperature drops to 33F or exceeds 80F with a 10F "deadband" (pump stops at
43F and 70F).  The primary and secondary pumping is not a direct issue as I
believe I can run the model with the secondary pumps for their energy use
and then eliminate them for subsequent modeling.  I have tried to assign the
well field pump to the HX under Attachments, but this fails to take.  eQuest
help generally says to create a separate loop for the HX with its own pump.
However, I can not get this to go as there are no systems assigned to this
loop and get an error message for no load for design.  The 50% flow through
the well field seems to create an issue with the primary/secondary loop flow
as it appears that primary flows in eQuest are expected to be greater than
or equal to secondary flows.  (I have experienced a similar issue with
boiler water loops that draw a portion of the water from the main heating
loop.)

Any ideas on how to deal with this?



-- 
Ron Pecarina, PE, CEM, LEED-AP
Energy and Sustainable Design Consultants, Inc.
1128 Noblewood Drive
Billings, MT   59101
406-208-0227
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