[Equest-users] Can't force pump power to Zero?

[Demba Ndiaye]

What happens is that a blank ("") is equivalent to a zero (it is not an eQuest problem, but rather a programming language problem: the conversion of the string "" or of the string "0.00" leads to the same numerical value 0.0).

So when you input "0.00" it is like leaving the field blank, and then eQuest will use the head and the gpm (along with motor efficiency and mechanical efficiency) to size; and if the head is not input, it will autosize.

The solution in this case is to input "0.01" or lower.

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Demba NDIAYE

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Eric Studer
Sent: Thursday, April 15, 2010 7:30 AM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Can't force pump power to Zero?

Another trick is to let the pump do whatever it wants, but make a ghost electric utility meter to handle all the electric end uses that are included in the model to simulate non-standard systems.  The energy use of the various meters will be reported separately in the PS-F reports, so use the output from the EM1 when calculating actual project energy use.

Eric

Ph:   (781) 431-1100 ext 12
Fax:  (781) 431-1109

________________________________
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Carol Gardner
Sent: Wednesday, April 14, 2010 4:24 PM
To: Pasha Korber-Gonzalez
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Can't force pump power to Zero?

I agree with Pasha. Additionally, you might want to put in a really low number for the pump head. Maybe try one at a time and then both?

Carol
On Wed, Apr 14, 2010 at 1:05 PM, Pasha Korber-Gonzalez <pasha.pkconsulting at gmail.com<mailto:pasha.pkconsulting at gmail.com>> wrote:
James.  I would suggest trying 0.0001 for your input.  sometimes DOE2 doesn't like an exact 0 number value, so I typically practice with input values set at 0.001 or as low as I can input with the value restrictions.

that's what I can offer for now.

Pasha
On Wed, Apr 14, 2010 at 8:56 AM, James Hansen <JHANSEN at ghtltd.com<mailto:JHANSEN at ghtltd.com>> wrote:
I've got a fairly simple primary/secondary chilled water system with a waterside economizer chiller.

I've already got a secondary chilled water pump circulating primary chilled water to the systems in my proposed building, and it does double duty as pumping through the heat exchanger in my proposed design.  So the chilled water pump that I've set up for the waterside economizer (to regulate maximum flow) really has Zero power consumption.

However, when I set the KW to 0.00 for this pump, eQuest is STILL auto-sizing something and forcing the KW to around 32 KW.  I even set the efficiencies to 1.0 to see if that made a difference (doesn't).  I'm not sure if it has something to do with the warning about the pump not being able to match system flow at the minimum required head...but why can't I force this KW to 0??

Has anyone ever run into this?  Here's a screenshot of my input for that pump and the PV-A output.  Thanks in advance!

GHT Limited
James Hansen, PE, LEED AP
Senior Associate
1010 N. Glebe Rd, Suite 200
Arlington, VA  22201-4749
703-338-5754 (Cell)
703-243-1200 (Office)
703-276-1376 (Fax)
www.ghtltd.com<http://www.ghtltd.com/>

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The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com<mailto:ght at ghtltd.com>, and destroy this communication and all copies thereof, including all attachments.  Thank you.

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