[Equest-users] [Bldg-sim] loop to loop heatpump in equest

Nick Caton ncaton at smithboucher.com
Fri Jul 24 11:09:15 PDT 2009

I've chatted with Rashmi and feel like others may want to know how this
can be done in the future...  Also copying [Equest-users] on this
discussion as advised by a list administrator.  



See attached screengrab for a simple visual of how I accomplished


Setting up the 4-pipe system sourced from a closed ground loop:

1.	Create a 'chiller' of the type 'water-to-water heat pump'
2.	Create an independent circulation loop of the type 'lake/well'
3.	Create a ground loop heat exchanger of the type 'lake/well'
4.	Select as the chiller CW loop and GLHX circulation loop the
independent loop you created - they should connect without errors
5.	Assign a custom temperature schedule for the lake/well ground
loop in the screen that pops up when you double click the GLHX (read on)
6.	Make sure the default head/pump properties for the circulation
loop and GLHX make sense for your system - adjust as necessary.  (i.e.
if it's a closed ground loop, there shouldn't be static head)


The tricky thing is that both Rashmi and I were dealing with closed-loop
ground heat exchanger (not lake/well).  The solution I came to model
this was to temporarily save the project in a separate directory to keep
my work, then go back to the wizards and heat/cool the same building
reasonably using the DX/DX heating/cooling ground source heatpump
option, with all appropriate ground and field properties well defined.  


Once this is done, you can have eQuest additionally generate an hourly
report over of the resulting ground loop temperatures throughout the
year (actual procedure eludes my memory, but it's in the archives).
Once this is done, I used that raw data to come up with the resulting
weekly average temperatures in the ground loop using excel.  I then used
these figures to create a custom temperature schedule for the actual
project, which was assigned to the GLHX as mentioned above.  This way
you're reasonably accurately representing what temperatures the
water-to-water equipment is seeing coming out of the ground throughout
the year based on your actual geographic, ground loop, and soil
condition variables as defined.


The final logical step, and one I'm currently working on learning for
myself, is defining a custom performance curve for the water-to-water
equipment that's representative of the real thing.  I have been advised
the default chiller curves as well as the water-to-air heatpump curves
from the Climatemaster eQuest add-on are not appropriate for modeling
water-to-water heatpumps. 


Best of luck!


PS: Apologies for the screenshot's quality - I had issues making it
small enough for the mailing list to accept.




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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Anthony
Sent: Friday, July 24, 2009 10:13 AM
To: 'Rashmi Sonal'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] loop to loop heatpump in equest


Would the following get you close enough (ignoring the DOAS side)?


1)      Specify a water-air HP system

2)      Zero out the fan energy

3)      Factor the load side pumping energy into the EIR of the HP

a.       Alternatively, you could add your load side pump energy to the
source side pump


Obviously there's limitations either way and I've never tried this, just
thinking out loud.  Certainly someone else out there can comment who has
attempted this?


Anthony Hardman

Mechanical Engineer

Geo-Energy Services


From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Rashmi
Sent: Thursday, July 23, 2009 3:39 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] loop to loop heatpump in equest


Hi All, 


I am trying to model a building with water-to-water heat pump connected
to ground HX and 4-pipe AHUs with induction unit at the terminal. 

I have specified induction unit at the terminal, to model active chilled
beams, with a dedicated outdoor air unit. But with this configuration on
airside I am not able to attach the water to water heat pump to any
condenser water loop on the water side. Is there a way I can model GSHP
serving active chilled beams in equest?


Thanks in advance. 


Rashmi Sonal, LEED AP

Environmental Designer
Computational and Simulation Analysis (CoSA)

Tel: (+1) 212 616 0285

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