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# SubCooling

Member Posts: 2,144
When estimating SC for R22, the vertical rise is figured at, every two feet of rise there is a 1 lb. press drop. What is it for R410A ?

## Comments

• Member Posts: 68
Pressure Drop

If I am reading Trane's guide correctly, it shows .43 PSI drop per foot of liquid lift.

Jerry
• Member Posts: 678
edited June 2014
Jerry is right.

Again, I am old and use rules of thumb that my dad and grandad taught me.  I always use 1/2 PSI/foot pressure drop for the liquid column lift (probably incorrectly, I apply this to all refrigerants.)  Amazing how the old dudes that came before us knew this stuff without the access to the science that we use today.

My grandad was installing air conditioning and refrigeration in the late 40's and early 50's, then dad followed him.  Almost all of my "Rules of Thumb" were beaten into my head by them.

Grandad's #1 rule when I started working with them and learning the trade:  First thing every morning, put your P & T chart in your shirt pocket along with a notebook.  You are useless without them.

Still today, it is part of my morning routine (even on my off days, haha).

Chris
• Member Posts: 1,726
If

43 psi is correct at aprox. 8' of lift you will have ZERO pressure.
• Member Posts: 349
0.43 psi/ft, not 43 psi/ft

Rules of thumb, which you all know I hate, suggest using 0.50 psi/ft.
Eugene
• Member Posts: 2,144
Rule of thumb'ssssssssssssss

LOL Professor! I STILL FEEL the look you gave in your "Psychrometrics w/o Tears" class when I brought up a R.O.T. ! Still LOL!
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