Compressor flooding

[Tommy knocker]

I dont know if you mis-understood me or your just an arrogant prick. But never once claimed I had a subcooled suction line. I said temp was originally 25 and rose to 32degrees as I added some refigerant.

Easy big fella. Your numbers are confusing. You said originally 25 degree suction with 38psi. That would indicate a sub cooled condition. Even if you added refrigerant and raised the suction to 32 the SST is 44+ so something isn't adding up. Maybe we are talking about different things. When you say suction temp are you talking about saturated suction temp, from your PT chart, or the actual suction temp, taken with a thermometer?

[jpsmith1cm]

Given that 414b is a blend, what you're describing is THEORETICALLY possible, though.

If that is the case, you're dumping almost PURE liquid into that compressor and it's probably already dead.


Time to start at the beginning and find out WHY you aren't absorbing enough heat in the evaporator to fully boil all of the refrigerant being fed by the TEV.

Dirty? Fans? Oversized valve? Valve stuck open?

[jpsmith1cm]

I've seen a number of them over the years, only on R12 systems

I've seen them on systems with any flavor of juice in them, just not commonly on "single"
type condensing units.

[fr420]

You said that you measured a 38 pound suction line with 414b, then disagreed with me when I pointed out that it was impossible for ice to form at that condition. (47 degrees Saturation Temp)

Didn't disagree, was just trying to explain myself better. I swear to you that with my 38lb suction I had a 32degree suction line, and before I added the extra refrigerant my suction temp was 25degrees. I even checked my guage with another gauge.

You said that you thought that you should use the bubble point (liquid side) for the suction line (32 Saturation temp). This is incorrect, you would use DEW point for the suction side of the system.

I agree you use dew point for suction side. But with the readings I was getting that didnt add up. so I thought to myself maybe because I'm flooding and there is liquid in the suction line that I should look at bubble point. Because the readings made sense the, but maybe I'm way off with that.

So, I'm using what you've given me of your readings and some simple math to point out why I think that your readings are erroneous.

You can call me an arrogant prick if you like, I've been called worse and I'm still standing.

What I do know is refrigeration, and something here isn't adding up.

This site I always thought was to help each other, not to be-little people by trying to prove your smarter, so unless you have any suggestions I personally dont need any of your comments about my erroneous readings

[2sac]

Without proper readings everyone is making guesses

[fr420]

Easy big fella. Your numbers are confusing. You said originally 25 degree suction with 38psi. That would indicate a sub cooled condition. Even if you added refrigerant and raised the suction to 32 the SST is 44+ so something isn't adding up. Maybe we are talking about different things. When you say suction temp are you talking about saturated suction temp, from your PT chart, or the actual suction temp, taken with a thermometer?

Actual with a thermometer, and I know the numbers are confusing that's why I'm asking for help.

[coolerik]

Either u gotto some f ed up stuff goin on or yer insternents are out.... its friday and im well into a case so im having a hard time deciphering the numbers.. oh and go Canucks,!! Sorry ****cago blackcocks

[jpsmith1cm]

You want to stick with dew point data for the suction line.

Look at how a blend works. At a given pressure, you start evaporating at the bubble point. This is the lower of the two readings given. In our case, that is 32F. As the refrigerant continues to boil at a constant pressure, the temperature actually rises to the dew point readings.

This is why it is THEORETICALLY possible that your readings are accurate but, if they are, your compressor is in a WHOLE lot of trouble.

I would start looking closely at the evaporator and what is going on there that is causing you to either not absorb heat or to overfeed refrigerant.

[icemeister]

As was mentioned early on in this discussion, it's possible the compressor isn't pumping as it should. If the valves are bad and it's only pumping at 50% capacity, your TXV will be way oversized and tend to cause such a flooding condition.

At this point, I usually check the compressor amp draw against the manufacturer's published performance data. Get the compressor model number, the actual supply voltage, the suction & discharge pressure and we can look it up. It's amp draw should be withing 10% of what the data says it should be or you have a bad pump.

[Tommy knocker]

Actual with a thermometer, and I know the numbers are confusing that's why I'm asking for help.

Ok. I'm going to suggest you verify your gauges and thermometer are calibrated and correct. If they are then your problem is over my head. Would have to be there and put my hands on it.

[Dchappa21]

I would recommend recovering your gas and starting with virgin refrigerant.

Could be your gauges too.. Have you tried another set?

Normally with that high of suction pressure your high side will be through the roof.

So, it's either a bad compressor, bad gauges, or mixed gas.

I would also check you equalizer line on your valve.

[Dchappa21]

Whoops missed where you said no equalizer line... How old is the coil? No distributor right???

[eddiegoodfellar]

Any large leaks on the system in the past? Maybe it's time for some virgin refrigerant.


I would recover some refrigerant and check the saturation to make sure the refrigerat itself is good.
This and the compressor efficiency test could save you a bunch of time in the long run.

I pretty new to refrigeration but that is where I would start.

Please post your findings when they are determined.

[thethomas4]

Yea, thru the TXV equalizer but the SH would be way low measured at the compressor and way high measured at the evap but wouldn't one visually see this while troubleshooting?

Here is a picture of what that looks like on RIFF case. Coil and distributor was clear case at 35*

[icexprt]

So, you're now claiming a subcooled suction line?

32F SCT (this is wrong, but I'll play along) with a 25 degree suction line?

5 degrees suction subcooling?



Your readings are wrong, friend.



icexprt,

I've seen suction/liquid heat exchangers blow out and leak through. Not very common to see that particular part on smaller equipment like this.

Maybe I'm using the wrong term to describe the part I'm referring to.... Refrigeration Research calls it a "subcooling heat exchanger". I've attached a picture... I hope it works...first time posting a picture! I've seen them on even smaller walk-ins before.

[jpsmith1cm]

Maybe I'm using the wrong term to describe the part I'm referring to.... Refrigeration Research calls it a "subcooling heat exchanger". I've attached a picture... I hope it works...first time posting a picture! I've seen them on even smaller walk-ins before.

Yeah, I knew what you were talking about.

I've seen a few of them rupture before. Finding the first one is the worst.

They don't do a lot of subcooling, really.

[fr420]

Maybe I'm using the wrong term to describe the part I'm referring to.... Refrigeration Research calls it a "subcooling heat exchanger". I've attached a picture... I hope it works...first time posting a picture! I've seen them on even smaller walk-ins before.

Thanks for all your help guys and sorry I got a little pissy at times. The promblem was the the subcool heat exchanger!!!!

[jpsmith1cm]

Thanks for all your help guys and sorry I got a little pissy at times. The promblem was the the subcool heat exchanger!!!!

Good find.

My first one took me 3 service calls over 2 days to find and correct.

[fr420]

You want to stick with dew point data for the suction line.

Look at how a blend works. At a given pressure, you start evaporating at the bubble point. This is the lower of the two readings given. In our case, that is 32F. As the refrigerant continues to boil at a constant pressure, the temperature actually rises to the dew point readings.

This is why it is THEORETICALLY possible that your readings are accurate but, if they are, your compressor is in a WHOLE lot of trouble.

I would start looking closely at the evaporator and what is going on there that is causing you to either not absorb heat or to overfeed refrigerant.

I understand exactly what your saying, but the condition I was having The dew point reading would give me a subcooled suction line, and the bubble point reading was only one that made sense because as we know now I was coming back straight liquid.

[jpsmith1cm]

I understand exactly what your saying, but the condition I was having The dew point reading would give me a subcooled suction line, and the bubble point reading was only one that made sense because as we know now I was coming back straight liquid.

Follow what is actually happening with the dew point/bubble point.

The area between the two is the saturation area of the refrigerant and liquid can exist at any point between the two.