# Wizard DX EER Correction

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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

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Joined: 2010-11-03
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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 I do apologize if it is out of date, misinterpreted, or mistyped.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

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Joined: 2011-09-30
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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

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Joined: 2010-11-03
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Scott Criswell knows what's in the background. Scott.Criswell at doe2.com.

Carol

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Joined: 2011-09-30
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Attached is a reference on converting EER and SEER to Cooling EIR.

Hope this helps,

Mike

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Joined: 2011-09-30
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