Oscillating Evap Temps

[comment]

Hey all :)

I'm having this problem with my Vapo LS that the temp on the evap oscillates when working under ambient temps below app. 20°C. It doesn't matter if the system is idleing og working full load - only difference being a slighty higher temp and more frequent oscillation under load.

I got a few screenies to illustrate. First a log graph screenie showing the system idleing for about 2 hours at 10°C ambient temp:

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Next is a log graph screnie showing the evap temp running the system full load at 10°C ambient temp, again for app. 2 hours:

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Notice that the oscillation is more frequent running the system full load: 6 peaks under load as opposed to 4 idleing.

Anybody got a clue why this oscillation happens?

Btw: For these screenies I was using a P4 2.8B @ 3.9GHz. Vcore being 1.600. CPU heat emission app. 104Watt (calculated with GORK’s OCTools 2.0).

[Gary Lloyd]

Is the condenser fan speed oscillating?

[HawainPanda]

maybe ur not giving it enough juice...maybe if ur living in an old house...the outlets prob can't provide enough power...

[comment]

The condenser fan is running full speed. No oscillation as far as I can see in the WinCC Status Area and by looking/listening at/to the fan.

And power shouldn't be a problem either.

Btw: At temperatures above app. 20°C I don't get the same pattern. The system boots at minus fortysomething degrees and within 15-20 minuts the compressor starts seething and the temp rises 8-10°C. Then the evap temp stabalizes. A log graph screenie to illustrate:

[LoudHoward]

Stop kicking your LS :D

[comment]

Originally posted by LoudHoward
Stop kicking your LS :D Do U really think that would help. Thought I was supposed to kick it every now and then :hehe:

But surely will consider not doing that again :wierd:

[Shane5578]

same prob as decay then. he also mentioned seething which i haven't heard from mine

[comment]

Originally posted by Shane5578
same prob as decay then. he also mentioned seething which i haven't heard from mine Well I kinda heard about him. Check out the first post in this thread (http://forum.vapochill.com/showthread.php?threadid=6262) :D

Even if you don't get any seething, do you get a temperature rise upon cold booting, as shown i the third screenie?

[Shane5578]

i'm confused about your third screenie.

app. 20°C ?- what does that mean?

does the seething go away, like the watery sounds goes away?

tbh i suspected your vapo unit ever since you mentioned garbled letters on the LCD.

[comment]

Originally posted by Shane5578
i'm confused about your third screenie.

app. 20°C ? The third screenie shows how the evap temp behaves at approximately 20°C ambient temp.

[Shane5578]

so the oscillation occurs only when the ambient is below 20c.

is that right?

[comment]

Originally posted by Shane5578
so the oscillation occurs only when the ambient is below 20c.

is that right? Exactly.

[Gary Lloyd]

The lower the ambient, the lower the high side pressure. The lower the high side pressure, the less refrigerant is pushed through the cap tube. A point can be reached where there isn't enough refrigerant flow to handle the load. If the system is slightly undercharged, that point will be reached sooner.

You may want to put a temp sensor on the suction line a few inches from the compressor, see how cold it is and if it oscillates.

[Shane5578]

its hot around here. when i cold boot my vapo. the first thing i see on the LCD is +30c. so i guess my ambient is +30c

when windows loads and i run the software i see -43c. as long as i don't run anything intensive. the temps are steady.

from the third screenie. it looks like your running prime95.

[comment]

Originally posted by Gary Lloyd
The lower the ambient, the lower the high side pressure. The lower the high side pressure, the less refrigerant is pushed through the cap tube. A point can be reached where there isn't enough refrigerant flow to handle the load. If the system is slightly undercharged, that point will be reached sooner.

You may want to put a temp sensor on the suction line a few inches from the compressor, see how cold it is and if it oscillates. Would the seething, that starts just before to the temp rise, indicate that the compressor is undercharged?

Btw: The suction line being the line running from the compressor to the evaporator, right? And if the temperature oscillates at that point, that indicates that the system might be undercharged?

I know many questions, hope you don't mind :)

[comment]

Originally posted by Shane5578
its hot around here. when i cold boot my vapo. the first thing i see on the LCD is +30c. so i guess my ambient is +30c

when windows loads and i run the software i see -43c. as long as i don't run anything intensive. the temps are steady.

from the third screenie. it looks like your running prime95. Yes it looks like I'm running Prime95 but I ain't. Did you ever check the log graph in the WinCC after say 30-40 minutes after cold booting?

[Gary Lloyd]

Originally posted by comment
Would the seething, that starts just before to the temp rise, indicate that the compressor is undercharged?

Btw: The suction line being the line running from the compressor to the evaporator, right? And if the temperature oscillates at that point, that indicates that the system might be undercharged?

I know many questions, hope you don't mind :)

Seething?

Yes, the suction line goes from the evap to the compressor. Once the system is down to temp, if the line is warm, the system is undercharged. This will be the first spot to warm up when a system has a leak (or not enough refrigerant to begin with).

[comment]

Originally posted by Gary Lloyd
Seething? Yes, it sounds pretty much as popcorn popping happily away. The colder the ambient temp the louder the seething.

[Shane5578]

Originally posted by comment
Yes it looks like I'm running Prime95 but I ain't. Did you ever check the log graph in the WinCC after say 30-40 minutes after cold booting?

i didn't look at the graph. i just kept an eye on the LCD every few mins.

so does the seething go away after awhile?

[comment]

Originally posted by Shane5578
i didn't look at the graph. i just kept an eye on the LCD every few mins.

so does the seething go away after awhile? At above 20°C it stops when the evap temp rises, as shown i the third graph.

Would you do me a favour and start the WinCC upon cold booting your system tomorrow and take a log graph screenshot after 40 minutes and post it in this thread?

[Shane5578]

sorry .
i would have to physicaly pullout my vapo from under the desk, i don't connect the usb cable anymore.

i'm too lazy:D

[comment]

Originally posted by Shane5578
sorry .
i would have to physicaly pullout my vapo from under the desk, i don't connect the usb cable anymore.

i'm too lazy:D You lazybones... Well I guess it's one of Gods great gifts to mankind :rocker:

[Shane5578]

lol