View Full Version : Chiller Done need help with charging.
After 15 mins of run i could not see frost at my evap and suction is still warm. The temps and pressure are not very good. I need help here.
This is the temps after 15 mins of run.
Evap temp measured at oulet of TXV - 22.0
6 Inches away from compressor - 28.5
This are the pressures
Low side - 6 In Hg
High side - 150 PSI
What is my problem. And i have not adjust the TXV as i do not know how.And i did not experience any hunting by the TXV. The pressures were constant.
Pictures of the chiller
http://img461.imageshack.us/img461/6148/high0zi.jpg (http://imageshack.us)
http://img461.imageshack.us/img461/4618/low6um.jpg (http://imageshack.us)
http://img461.imageshack.us/img461/5654/setup8kg.jpg (http://imageshack.us)
http://img461.imageshack.us/img461/1069/setup21dh.jpg (http://imageshack.us)
http://img461.imageshack.us/img461/7528/txv6uw.jpg (http://imageshack.us)
http://img461.imageshack.us/img461/161/txvposition1ab.jpg (http://imageshack.us)
TXV is a 1/8 Ton with 00 orfice.
expansionvalve
11-05-2005, 01:57 AM
What gas are you running and what's ambient temp?
Im uaing R22 and the ambient temps are ~28 c. I had a little accident just now the pin on my access valve was totally depress and could not come out and the refrigerant gushed out on me :mad: ... Had to get a new pin to replace it as it is totally screwed. I tried placing it in with the hose it becomes depress again. I lose a little oil as well. But i dont think i will be replacing it as it is not that much maybe a 5 ml.
Hope you can give me a guide to how to charge it again. I believe the pressures will be the same.
Gray Mole
11-05-2005, 02:16 AM
Well there's nothing seriously wrong with your pressures, just that you'll likely have to adjust the screw to make the changes you need.
I built a line chiller a while ago to get my head into chilling, and found that it wanted to run about 15psi low under load to get the best balanced load temps for me.
There's a couple serious problems I can see though, and you're likely gonna have to change 'em to make it work.
You need to run the pipe from the condensor ABOVE the filter. The down into the filter to a sightglass, then to the TEV.
If you don't have a liquid head to the TEV it's not gonna work, and you probably don't.
What I recommend...
evacuate.
chop the line from the dryer to the TEV.
Bend the line from the condensor so it goes up, then down with the filter pointing down, at least a little.
braze a sightglass onto the line from the filter that you left when you chopped it off.
run a new line to the TEV from the sightglass.
vacuum.
charge it until you've got a full sightglass.
Once the sightglass is full you've got your liquid head, and TEV's simply don't work without it. They can't meter the flow.
A real accumulator would be better, but the filter, and the pipe to the sightglass will fill with liquid. Just make sure after that you've got liquid in the glass both at idle and under load and you're set.
After that you can look at adjusting the screw to finetune, but until you change the configuration it's just not gonna work right.
I hope you understand what I mean, but basically if you think about it that you're trying to get liquid to flow upwards right now, you'll realise that it's just not going to happen unless you fill your condensor with a lot of refrigerant.
Gray
Gray
expansionvalve
11-05-2005, 02:26 AM
Sorry to hear about your little accident, hope your ok...
Has the unit any gas left inside now?
Back to the gas pressures you had, 150 head pressure -6suction pressure I would say you are under charged, I would add some more gas. I would add charge till I saw maybe 175/200psi head pressure and see what it like then.
Ic well luckily the refrigerant isnt cold. Or i may suffer something. I get what you guys mean already. I thought that having a pressure of more than 150 PSI would mean my system is inefficient and dangerous.
And thanks gray for your design thoughts. I learn quite a lot there. Well i guess i will change my design and i think i will get rid of the desuperheater and make a coil heat exchanger using 1/2" pipes and 3/8" pipes.
Now this is going to take some time again. But i do not want to rush things anymore as this is new for me.
expansionvalve
11-05-2005, 02:59 AM
Gray has indeed raised some very good points.
150 psi being inefficient and dangerous, first I have heard it put like that, it will only be dangerous if your joints are not upto scratch and inefficient if the condenser and fan are poor. r22 likes condensers with large area with good air flow to work well.
Personally, I think any system that doesnt have a high pressure safety switch is dangerous.
The fans i have can move 100 CFM of air. my condensor is kind of big but i was thinking of cutting it down to size like the chilly1 condensors are they good enough for the job. The fin area is quite large much more than mine.
I will try to get a sight glass and change a few things so that i can cut down on high side pressures.
expansionvalve
11-05-2005, 05:17 AM
If you chop that condenser down any I'm not sure you will reduce head pressure, if it were me I'd leave the condenser that size and add a fan shroud. I can't quiet see fan in the pictures so if it has one, I take it back :toast:
Actually my condensor was suppose to be an evap for a previous project the fin spacing was a little wide at least 0.5 cm. But it removes the heat quite well cause of the desuperheater which was a little oversize.
I am asking the refrigeration shops ard to custom made me a condensor like chilly's a 6 row one to help me save up some space in height and better thermal removal. If it goes well i would have one else i would have to stick with this. I will wait for a while while i redesign this thing. I want to do it well:)