# MERM page 33-3 error in EER formula?



## tim1981 (Apr 10, 2013)

COP = Coefficient of Performance

ref = for a refrigeration cycle

hp = for a heat pump cycle

Qi = Heat flux in

Qo = Heat flux out

Wi = Work in

33.1

COP(ref) = Qi/(Wi)

33.2

COP(hp) = (Qi+Wi)/Wi

therefore

COP(ref) = COP(hp)-1

and

COP(hp) = COP(ref)+1

That makes sense: COP(hp) = (Qi+Wi)/Wi = Qi/Wi + Wi/Wi = COP(ref) + 1

EER is the same thing except that the units on the top and bottom are different:

33.3

COP = 3.41 X COP

33.4

EER(ref) = Qi(btu/h) / Wi(watts)

33.5

EER(hp) = [Qi(btu/h)+Wi(btu/h)] / Wi(watts)

similar to COP:

EER(hp) = Qi(btu/h)/Wi(watts) + Wi(btu/h)/Wi(watts) = EER(hp) + Wi(btu/h)/Wi(watts)

Since the numerator work is in btu/h and the denominator work is in watts, the second term is not 1, it is 3.41. However, 33.5 states:

EER(hp) = EER(hp) + 1

Am I losing my mind from studying for this too much, or is this a mistake in the MERM? If I find a mistake in the MERM, will they give me a PE license without having to take the test?


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## Lumber Jim (Apr 10, 2013)

Their Messing with your mind MAN...


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## shixiangnan1002 (Mar 28, 2014)

I found the same when I read that part. I firmly believe it is a mistake. Can't believe it's been there for so many editions...


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## slickjohannes (May 28, 2014)

When I took the FE last fall, I thought I found a mistake with a thermo problem in the FERM, so I followed the directions given in the front of the book and emailed PPI. I don't have my MERM in front of me, but I'd be surprised if the same instructions are not in the front introduction of the book.

Long story short, I got an email back from Lindeburg himself. I about fell off my chair seeing that he took the time to respond! He also told me I'd do fine on the FE exam. That may have been the one piece of confidence I needed to pass!


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