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View Full Version : Proper piping technique



hvac01453
19-10-2002, 10:18 PM
I've been working on a 15 ton split chiller and the unit doesn't seem to be piped correctly in my eyes. The Unit has a plate heat exchanger that has the TXV entering the bottom of the exchanger. I was thinking two ways of this, one pro, one con. The pro side is, this would force any liquid to boil in order to escape its own gravity, thereby protecting the compressor. The con is, the oil would most likely want to log in the bottom of the exchanger. I've seen many manuals showing the entry on the top OR bottom. I'm just not sure if one was reversed just for diagram purposes. Does anyone know if there is a hard and fast rule about this???

superheat
21-10-2002, 01:32 PM
A system with the evap piped from the top should have a liquid line soleniod and a pump-down cycle. Many medium temp systems are piped from the top without a LL soleniod. Does not seem like the best way to protect the compressor. Evap is typically the coolest place. All the ***** will migrate to the evap in the off cycle. When the compressor starts, it could get a shot of liquid.

hvac01453
22-10-2002, 12:31 PM
If you'll notice, I said the evaporator was piped from the BOTTOM, not the top! In most cases, even the TXV will slam shut and prevent the refrigerant from getting into the low side, but I do agree the LL solenoid is always a cheap insurance plan.