[Equest-users] More about fans

[Bill]

Steven, Vikram, et. al., 
 
Reid communictated with me in developing that presentation, since I authored
the spreadsheet tool.  As the author of the tool, I will vouch for the
analytical approach, and the tool was peer reviewed since it was funded by
the California Commissioning Collaborative.
 
As for tool useability, well, it is pretty useable but not where I would
like it to be.  The tool (and others) is available at:
http://www.cacx.org/resources/rcxtools/spreadsheet_tools.html
It was developed in Excel 2003; I am uncertain whether there are any issues
with other versions.
 
Yes, I believe the default DOE-2/eQuest VAV curves are quite optimistic.
Even the tool that comes out of my spreadsheet tool is likely somewhat
optimistic, even though it attempts to include fan, VFD, and motor
efficiencies at the various operating points.  Pressure drops relative to
flow could be slightly better modeled for the portion of the system with
filters and coils, and that would further increase off-design power.
 
How well a particular curve fits a particular system is most significantly a
function of 
(1) whether and how the static pressure setpoint (to which the VFD controls
the fan speed) is reset.
(2) if the static pressure setpoint is not reset, where the sensor is in the
duct system, and how high the setpoint is relative to the fan pressure rise.
 
This figure is related to what Reid showed in his presentation, and relates
some of these issues.
 
--Bill
 

 
 
 
William E. Koran, P.E. 
Senior Engineer 
Q u E S T 
Quantum Energy Services and Technologies 
3945 Parker Road 
West Linn, OR  97068 
Voice: 503-557-7828 
Fax: 510-540-7268 
Web:  <blocked::http://www.quest-world.com/> www.quest-world.com

  _____  

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Steven
Savich
Sent: Friday, March 05, 2010 3:03 PM
To: 'Vikram Sami'; 'eQUEST Users List'
Subject: Re: [Equest-users] More about fans



Vikram,

 

Reid Hart of PECI did a presentation on this issue for the building
simulation user's group a few months ago, and discussed a spreadsheet tool
to construct accurate DOE2 performance curves for variable flow air and
water systems.  I believe the powerpoint presentation is still archived on
the BSUG yahoo site, and the spreadsheet is downloadable from PECI's
website.  I haven't tried using this tool yet, so I cannot vouch for its
accuracy or useability.

 

Steven

 

Steven Savich, LEED AP

Systems West Engineers

411 High Street

Eugene, OR  97401-2427

(541) 342-7210

(541) 342-7220 (fax)

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Vikram Sami
Sent: Friday, March 05, 2010 2:01 PM
To: eQUEST Users List
Subject: [Equest-users] More about fans

 

Same model - different fan question. Table G3.1.3.15 Gives you a part load
performance table for VAV fan systems. Based on that, I created a
performance curve (linear) for my VAV fan system that looks like this:

 



 

 

Problem is when I use this as opposed to  the default curve that came out of
the wizard, the fan energy doubles. The fan energy is still only 8% of the
overall building load, so its not alarming. Does this mean that the default
curve was way to low? Is the method above the way to model this performance
curve?

 

Thanks for your help

 

Vikram Sami, LEED AP 
Direct Phone 404-253-1466 | Direct Fax 404-253-1366 

LORD, AECK & SARGENT ARCHITECTURE
1201 Peachtree Street NE, Suite 300, Atlanta, GA 30361 
Responsive Design . Technological Expertise . Exceptional Service 
Please visit our new website |  <file:///\\www.lordaecksargent.com\>
www.lordaecksargent.com

P Think GREEN before you print.

 

 

 

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