[Equest-users] Primary-secondary loop configuration

[David S Eldridge]

First:  To match the example shown in the diagram from the manual, the chillers do not have dedicated pumps, which both of your eQuest files have.  If this is changed in your model, I think the graphics will match what you are expecting to see.  You don't need a "Primary Loop" in the diagram/tree in order to model it, depending on if the chillers have dedicated pumps or not.
Anyway - the first screen capture from wizard shows four chillers, each with their own pump, providing water to a secondary "Chilled Water Loop" with a pump (and therefore not the primary loop, unless this pump was somehow in series with the individual chiller pumps), from which the coils are served.  This matches your text description of what you want to model.  (Not specified was if your design had dedicated pumps.)
Your detailed mode screen shot shows four chillers with their own pumps, providing water to a loop without a pump (this could be considered to be part of the primary loop as it has no means of operating without the plant's pumps), and serving a secondary loop with a pump.  The "primary loop" here is merely a construction to assemble the pieces - since the chillers each have their own pumps, it probably represents a portion of the plant's primary loop when mapped to the as-built building.  I suppose this also matches your description, but has an extra piece of programming that is not needed.  Your run might take an extra 0.05 seconds ;)  You can verify that the results of the two runs are the same, unless the extra loop has some specified losses not accounted for in the prior model.
To make a long story short - the items shown in the explorer view of eQuest can mean different things depending if the chillers are created with dedicated pumps or if the pumps are on a common header pipe.
David


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Riemer
Sent: Thursday, February 05, 2009 4:25 PM
To: 'Karl Stum'
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Primary-secondary loop configuration

In my vernacular:
a pump that exists to push water through primary equipment (i.e. a chiller) is a primary pump
a pump that exists to push water through secondary equipment (i.e. a cooling coil in an air handler) is a secondary pump
a pump that pushes water through both generally does need a specific name because it is usually the only pump
but I see that my vernacular cannot adequately name the components in their example.

If you are trying to replicate their example, I think you would be better to go through the wizard choosing "Single System Pump(s) only " and describing only the CHWP-1 pumps.
Then in the detailed interface add your additional loops and pumps (CHWP-2 and CHWP-3).
I am done for the day, so good luck.
Paul




From: Karl Stum [mailto:kstum at summitbe.com]
Sent: Thursday, February 05, 2009 3:59 PM
To: Paul Riemer
Cc: 'Dennis Hunt'; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Primary-secondary loop configuration

Thanks, I can see your point when looking at the schematics. But, how do I reconcile the tree structure without two circulation loops with the DOE Topics Vol. 2, p. 312-313, merged and pasted below?
[cid:image001.gif at 01C987AE.D43DF7E0]

____________________________
Karl Stum, PE
360 573 5700 ofc
360 771 0918 cell
Summit Building Engineering
________________________________
From: Paul Riemer [mailto:Paul.Riemer at dunhameng.com]
Sent: Thursday, February 05, 2009 1:42 PM
To: 'Karl Stum'
Cc: 'Dennis Hunt'
Subject: RE: [Equest-users] Primary-secondary loop configuration

Karl,
Maybe you and I are on opposite sides of the naming convention too but I will offer my take on the naming issues.
In your first screen capture.  I would call the "Chlr#* (Screw) Pump"s dedicated primary pumps on implied primary loops and the "Chilled Water Loop" is a secondary loop with "CHW Loop Pump" the secondary loop pump.
In your second screen capture, I would still call the "Chlr#* (Screw) Pump"s dedicated primary pumps on implied primary loops,  the "Primary CHW Loop" is a secondary loop without a pump and your "Secondary CHW Loop" is a tertiary loop with a pump.
Good luck,
Paul


From: Karl Stum [mailto:kstum at summitbe.com]
Sent: Thursday, February 05, 2009 3:19 PM
To: Paul Riemer
Cc: 'Dennis Hunt'
Subject: RE: [Equest-users] Primary-secondary loop configuration

Paul,
Thanks for the response. Here's the tree structure. It only shows one loop. I really question the validity of what the Wizard is doing. So, I went into the detailed mode and created another circulation loop and set it up the way I think it should be, but if that is right, then the 100's of Wizard set ups by modelers everywhere are messed up, and I doubt that????  See the tree from the detailed set up I did in the second image below. The problem with that one is I can't get the one coil load to get off the primary loop and I don't trust it, if it is so different than what the Wizard sets up.

[cid:image002.jpg at 01C987AE.D43DF7E0]

DETAILED SETUP CREATING A SECONDARY CIRCULATION LOOP.
Now chillers are assigned to the primary loop, the secondary loop assigned to primary loop and loads are assigned to secondary loop (except when I assign the DDS(B) load to the secondary, it looks OK in the tree, but the schematic looses the secondary loop altogether??).
[cid:image003.jpg at 01C987AE.D43DF7E0]




____________________________
Karl Stum, PE
360 573 5700 ofc
360 771 0918 cell
Summit Building Engineering
________________________________
From: Paul Riemer [mailto:Paul.Riemer at dunhameng.com]
Sent: Thursday, February 05, 2009 1:07 PM
To: 'Karl Stum'; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Primary-secondary loop configuration

Karl,
EQUEST's pump & loop naming is unconventional and confusing.
I think you are have solved it and looking at the water side component tree view with all the +'s expanded should solidify it for you.
Let's just all be thankful that DOE2.2 gives us multiple loops and pump curves.
Paul



From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Karl Stum
Sent: Thursday, February 05, 2009 2:41 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Primary-secondary loop configuration

Chilled water primary-secondary loop configuration.
When using the eQuest Wizard and a primary-secondary chilled water pumping system is set up, I don't see the secondary circulation loop in the tree structure. Furthermore, per the DOE documentation, the chillers would be assigned to the primary loop and the cooling loads assigned to the secondary loop (DOE2 Topics Vol 2, p. 312-313), but the results from the Wizard show in the tree structure everything assigned to the primary loop, as does the output PV-A Plant Design Parameters report. In that report, the chillers do show term called  "(Run-around)" by their evaporators. Is this supposed to be what we would normally call the primary loop? Why aren't there two circulation loops showing up in the tree structure?
Thanks,
Karl
_____________________________________
Karl Stum, PE
Summit Building Engineering
2516 NW 91st Street
Vancouver, WA 98665
v. 360 573 5700
c. 360 771 0918
f.  360 573 5155
http://www.summitbe.com

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