[Equest-users] Chiller Curves

[Rob Hudson]

I have a new Chiller Curve question/situation.  I have created a custom
chiller curve for the EIR = f(PLR) as a cubic function using the following
data inputs:

1         .3313
.75      .2437
.5        .2201
.25      .1928

>From my understanding, the chiller curve seems correct.  However, when i
create a hourly report summary for the Corrected Chiller EIR and compare it
to the default EIR equation for this entry, i get 0.034 for the default and
0.072 for my curve at 25% ratio.  Why is it that the default is better than
my curve?  I have looked at the equation for the default entry and got the
following equations:

EIR = a + b x = c x^2
a = .04812248
b = .69573420
c = .23493889

at 25% this equation results in 0.2367, and my equation gets 0.1928

Is there any other calculations going on in the background that is causing
some problems?  I have attached an excel snapshot of the different EIR and
the corrected EIR values for two different chillers in my program.  Neither
is currently using the default EIR = f(PLR) curves, they are using custom
curves.

Thanks in advance,

-- 
Rob Hudson
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