View Full Version : changing to automatic valve

28-07-2006, 07:39 AM
We are talking about a freezer 2*2*3 metres. technoblock CSK 300U with comp. TFH 2511Z. one year ago one of my coworkers changed the capillary tube into an automatic valve( the one that is to adjust, without bulb)
Now the freezer could hardly go (the whole year round) below -16C. I was there yesterday to fix this problem but couldn't make it. had a terrible dispute with my boss. Tried to adjust the valve till suction was at 1,4 bar. (although 1,1 would be better) It was running 2,0 bar when I arrived and chamber was -16C. I tried to fill the system till compressor got cold but it got off on clixon. after 45 min I tried again (after changing drier)to adjust to 1,5 bar but again it got off on clixon. I tried several hours and nothing would be better than 2,0 bar suction. Then comp. got cold enough to keep running. I now think that this valve is not suited with this compressor for this purpose: -22C. My boss thinks it CAN replace the capillary tube.
what are you thinking of it. After the dispute with my boss I decided to quit. He called me incapable and irresponsible of my job. I even worked from 8am to 11pm and that was not enough to be responsible of the job?

29-07-2006, 11:02 AM
I am not quite sure of what kind of valve you are talkin about. But when you say " the one that is to adjust, without bulb", it must be somekind of a adjustable capillary (don't know the right name). What is the superheat?. And what is the condensing temperature?. Mayby the compressors motor havent got the power to start up agains the high pressure diff from the valve?. Have you noticed the pressures when it starts? Are they equal?. Finally the compressors valves might be broken, have you tested them?

29-07-2006, 12:50 PM
In my opinion, an AEV can always be used instead of a capillary tube. Both perform exact the same necessary action in a refrigeration circuit: making a precise pressure drop.

I think you have a fault with the compressor which has nothing to do with the AEV.
What's the current and the HP?

The valve equalizes after a shut-off just like with a cap tube.

Many ice machines I service have an AEV.

You speak about a TFH... so the 3 phase unit unit is running on R404a or the old R502.
In that case, 2 bar seems too high. I know these units evaporate around 0 bar when they reach -25C in the room. The evaporator is chosen for a big DT, mostly 15 to 20 K.
Was it not overfilled because it's not that easy to determine this without temperature and pressure readings?