TEV problem issue

[Lc_shi]

Hi sirs
one water loop heat pump tested at heating mode and run normally about half hour and stopped by low presssure alarm and occur again by restart. Adjusting the TEV counterclockwise to maxium and it can keep running and LP is a little lower than normal(comparing with another circuit). But while we readjust the TEV back and find the LP drop quickly. What is the problem? Is the TEV dirt -blocked or others? need you help. thanks in advance!


regards
LC

[Toosh]

Hi sirs
one water loop heat pump tested at heating mode and run normally about half hour and stopped by low presssure alarm and occur again by restart. Adjusting the TEV counterclockwise to maxium and it can keep running and LP is a little lower than normal(comparing with another circuit). But while we readjust the TEV back and find the LP drop quickly. What is the problem? Is the TEV dirt -blocked or others? need you help. thanks in advance!


regards
LC

Hi LC can you give us more info like pressures refrigerant and make and model number of unit

[nike123]

Hi sirs
one water loop heat pump tested at heating mode and run normally about half hour and stopped by low presssure alarm and occur again by restart. Adjusting the TEV counterclockwise to maxium and it can keep running and LP is a little lower than normal(comparing with another circuit). But while we readjust the TEV back and find the LP drop quickly. What is the problem? Is the TEV dirt -blocked or others? need you help. thanks in advance!


regards
LC

Revert adjustments and check superheat. If it is prety higher than it should be (while you have sufficient subcooling at TEV inlet) you have faulty/clogged valve.

Check this PDF http://www.mediafire.com/?tjyfwmjqyxl

[monkey spanners]

Also worth checking the evaporator for good flow, as if it is restricted, the tev will shut down to maintain superheat, in extreme cases this can cause unit to go off on lp switch.

[Brian_UK]

LC, you say water loop, if this means that the evaporator is a heat exchanger with a water loop then check also that the water flow is at design.