[Equest-users] Wizard DX EER Correction

Robby Oylear robbyo at rushingco.com
Wed Aug 13 16:55:49 PDT 2008


Thanks Paul,

 

We actually have that equation floating around the office and I wasn't
sure where it came from either.  Does anyone out there know where it comes
from?

 

By the way, it is a little misleading to say that EIR does not include
supply fan energy.  If you have convert an EER or COP from a manufacturer
to an EIR without using something to remove fan heat, then it will have
fan energy.  

 

I was hoping to use the wizard interface to remove the fan energy from an
ARI rated EER and was wondering if it was possible that anyone knew
exactly what was going on in the background.  The equation you gave
doesn't quite match the adjusted EER that the wizard gives out.

 

Robby Oylear

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

 <http://www.rushingco.com> www.rushingco.com

  _____  

From: Paul Riemer [mailto:Paul.Riemer at dunhameng.com] 
Sent: Wednesday, August 13, 2008 3:13 PM
To: 'Robby Oylear'; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Wizard DX EER Correction

 

I thought Andrew said this mostly well but maybe equations would help.

 

EER = (Cooling Output Btu/hr ) / (Supply Fan W + Compressor W + Condenser
Fan W)

 

COP = Output / Input and is unitless 

 

EIR = 1/COP (so it is also unitless) = (Compressor Input + Condenser
Input) / (Cooling Output)

 

So hopefully you see that EIR does not include supply fan energy.  All fan
energy is modeled in DOE-2 based on the separate fan energy inputs and
assumptions.  Of course ASHRAE 90.1-2004 Section 6 and Appendix G
including amendments prescribe baseline fan power limits and part load
performance.

 

I believe the Standard Test Procedure for determining the EER rating
includes a prescribed external static pressure but exactly what portion of
the total unit electric energy is due to the supply fan would vary a
little from unit to unit based on type of fan, internal static losses,
etc.

 

So the eQUEST WIZARD is removing an assumed standard fan component from
the entered EER and doing a units conversion to determine a cooling
efficiency (EIR) for DOE-2.

 

I have in my files: 

 

EIR =  (1/EER-0.012167)/((1/3.413)+ 0.012167)

EIR =  (1/SEER*0.778+1.4)-0.012167)/((1/3.413)+ 0.012167)

 

I do not recall where I found this but obviously I attribute it to the
above eQUEST development team. I do apologize if it is out of date,
misinterpreted, or mistyped.

 

I encourage digging deep through the program, its help files, and the
various archives and also attending a training session like the Energy
Center of Wisconsin's with Marlin Addison.

 

Paul Riemer

 

 


  _____  


From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Robby
Oylear
Sent: Wednesday, August 13, 2008 1:19 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Wizard DX EER Correction

Sorry to dig up an old topic, but I have a question about the wizard that
was talked about a year ago.  As mentioned below, the wizard will change
the efficiency you input into the program, but I can not figure out what
the change is based on.  One would assume its taking into account the fan
power, but by changing the fan bhp entry in the wizard I see no change in
the EIR that is output by the wizard.  

 

Does anyone have any insight as to how the wizard reaches the resulting
EIR for DX units?

 

Robby Oylear

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

 
<http://console.mxlogic.com/redir/?2OVtNCZSjqrXXRTDD3o0abt2sE4rlVsTvHECzBA
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www.rushingco.com


  _____  


From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Andrew
Craig
Sent: Wednesday, August 29, 2007 12:06 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] a qucik question about Cooling EIR -- eQuest

 

Anna---

The EIR in eQUEST is the combined efficiency of the unit condenser and
compressor while the ASHRAE code EER or SEER values are the entire
packaged unit efficiency.  You'll notice if you enter a published EER or
SEER in the wizard and then check the EIR output in the detailed edit
mode, it does not equal 3.413/EER because it isn't taking into account the
fan efficiency or inefficiency depending on how you look at it.

If you are doing a model for LEED, the way I have been advised to model
packaged units is to enter the ASHRAE Table values in the wizard (EER or
SEER) and let the program parse out the components of EIR and fan power.
Then, calculate the baseline fan efficiency and enter that number in the
detailed edit mode, overriding the wizard created value.

I have heard from members on the ASHRAE committee that Appendix G does not
handle this issue very well and it seems to be something that could be
refined.  If anyone out there has a more definitive stance on the proper
way to model packaged units in eQUEST with regards to ASHRAE/Appendix G,
please chime in.

Regards,

Andrew Craig, EIT, LEEDR AP | Mechanical Designer

INTERFACE ENGINEERING 

708 SW Third Avenue | Suite 400 | Portland, OR 97204 

direct: 503.382.2696

office: 503.382.2266

fax: 503.382.2262

email: Andrew_C at ieice.com

web: www.ieice.com 

Consultants of Choice to the Built Environment for over 35 years

Kirkland, WA | Portland, OR | Sacramento, CA | Salem, OR | SanFrancisco,
CA

-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Anna Liu
Sent: Wednesday, August 29, 2007 11:38 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] a qucik question about Cooling EIR -- eQuest

Hello all, 

I have a quick question about the Cooling EIR in

eQuest. If I got COP from ASHRAE90.1-2004 Table 6.8.1,

then EIR=1/COP. Does this caculation include the

supply fan electrical energy already or not? 

Thanks for your help. 

Regards, 

Anna

 

       

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