Quote Originally Posted by ryan1088 View Post
I've seen this on chillers with subcoolers on them. Seems like on those you get about 12 degrees before the thing clears. The first time I saw it I actually had 2 thermometers on there just to make sure I wasn't crazy.
My thinking is we are not reading an actual sub-cooling, more sort of an average of the stuff bouncing around in there. Some of it is sub-cooled, some of it is superheated, it is all shooting through the line so fast it does not have time to make a perfect mix/equilibrium.

Theoretically, 2 degrees subcooling would be a comfortable slight overcharge for a TXV to provide 100% liquid to the TXV, but in actual field operating conditions you will need 18 on a typical RTU. Below 16, bubbles.