# Thread: Calculating superheat and subcooling

1. Regular Guest
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## Calculating superheat and subcooling

Hey guys I have an assignment that I have to do and I am having troubles calculating superheat and subcooling. If someone could help me get the subcool/superheat temps that would be awesome. Please tell me what you did so that I can do it myself next time. Thanks in advance!

Refrigerant= MP39 (R-401a)

Liquidline= Pressure-120psig, temp-120F

Suction line= Pressure-30.5psig, temp-44.5F

Dishcharge= Pressure-176psig, temp-145F

Superheat=?
subcool=?

2. If you are learning this stuff you should be the one to do it.

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You need one of those pres./ temp charts. I carry one of those in my billfold, It's handy for me because I use so many types of refrigerants and can't remember which oils are campatible. I can't answer your question because of site rules. Internet is your friend, research.

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Originally Posted by JKopp
If you are learning this stuff you should be the one to do it.
yea, but they didn't teach us this. I have searched the internet and I can't find it. Can you link me somewhere? All I want to do is learn how to do this. I don't want the answer from you guys!

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Hint: convert pressure to temperature on a pressure/temp chart, whats the difference between measured temp and the one converted from pressure? (ans:superheat or subcooling)

LL will have the subcooling, but can be zero.

These are a critical component of understanding and properly charging and troubleshooting a HVAC/R system.

(Days of the Budweiser method are over)

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This is a great explanation especially since the refrigerant in question is MP-39.

http://www.achrnews.com/Articles/Ser...00f932a8c0____

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if you are in a learning environment i dont think your
instructor would give an assignment that the answers
cant be found in your text book. the glossary in the
back will most likely be your best friend while going to
this is a very basic question & one that you will use daily in this field
so dig out the answer & get your post count up so you can
get in the pro forums where you will get all the help you
will need

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Superheat=11.5F

Subcool=31F