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View Full Version : What do you do when a TXV is hunting?


Groganson
03-31-2010, 05:23 PM
What is going on w/ the system when a txv is hunting for correct superheat? I charged a split system w/ a txv to the correct subcooling but checked the superheat and the txv was opening way up and closing going frm 10 to 20 degrees superheat. Would I just have to adjust the txv manually until its correct?
Octopus
03-31-2010, 05:36 PM
What is going on w/ the system when a txv is hunting for correct superheat? I charged a split system w/ a txv to the correct subcooling but checked the superheat and the txv was opening way up and closing going frm 10 to 20 degrees superheat. Would I just have to adjust the txv manually until its correct?

Low load/ dirty evap restricted air flow
Groganson
03-31-2010, 07:28 PM
Your right it was reading fine for a couple of hours but the space must have cooled dwn and then there was no load. This site explains it pretty good http://www.achrnews.com/Articles/Service_and_Maintenance/82e2faf38c67a010VgnVCM100000f932a8c0____
tjc76
03-31-2010, 07:34 PM
If it was fine for a couple of hours then started to hunt- the valve is either oversized or your evaporator airflow is restricted. Are you sure there was no frost on the coil?
Groganson
04-01-2010, 08:29 PM
ya it was on a lieberte in a huge server room that they keep super clean and change the filters like once a month. There was a leak in the system and I repaired the leak and was recharging the unit, charged it to subcooling, got correct subcooling then checked the superheat and the unit was at a steady 15 degrees superheat then started going between 10 to 20 degrees hunting and was just wondering if I messed up the charge.
slb8101
04-01-2010, 09:11 PM
ya it was on a lieberte in a huge server room that they keep super clean and change the filters like once a month. There was a leak in the system and I repaired the leak and was recharging the unit, charged it to subcooling, got correct subcooling then checked the superheat and the unit was at a steady 15 degrees superheat then started going between 10 to 20 degrees hunting and was just wondering if I messed up the charge.Is the TXV bulb secure to the sucition line and insulated? you might try changing the bulb placement of the bulb.
Octopus
04-01-2010, 10:18 PM
If I had to guess you use to have 1000,0000000000,00000000,0000K of heat generated by vacuum tube electronics and since modern technology came by and we use solid state electronics now and produce 10k of heat and they kept that enormous unit. What happens it's under no load and with no load the txv hunts.