Carrier 23xl chiller-Low discharge superheat alarms

[Bradysmill]

Hey to all of you....Just found this site and thought I would give it a try....

I have a Carrier 23XL2020EC60 FRAME 2 machine, that keeps going off on low discharge oil temp.

Arrived on jobsite to an alarm of (OILSS) oil level sensor. Oil was so low, that the level sensor wasn't made, so I added about 3 gallons to the Heater sump (probably too much....) waited till it heated up and started machine....

Oil came back eventually and I took out what I put in ...or so I thought.

Later the machine faulted on Low discharge superheat.
So I figured I still must have excess oil in the machine and shut it down....waited till the heater heated up the sump oil to boil the refrigerant off and then drained out a little more.....

Now the machine faulted on (oilSS) again.....so I added some back in......

End result is this.
1.)Startup ramps to 87%
2.)oil temp falls to 116*f
3.)Cond. Refrig. temp 93*f
4.)Discharge superheat = 23*f
5.)Oil separator is 1/3rd full
6.)Oil is leaving sump and getting lower
7.)7*f cooler aproach
8.)Evap refrig. temp= 46*f
9.Condenser refrig. temp. = 96*f
10.)Discharge superheat and oil temp always about the same.
right now is 119*f
11.)Condenser water in is 80*f
12.) Condenser water out is 88*f

Discharge superheat is not between 30 - 40*f as it should be......Will alarm if sensed after a 30 min run time (a 10 min. interval of Less than 20*f.)

After running about 20 minutes....the machine starts to ramp down....
Level comes up to completely fill the glass on the heater sump and the single glass on the oil separator will gradually fill completely also....

This happens all while discharge superheat continues to fall to about 9*f.

Unit will shut down on alarm after running for the 30 min.+ the 10 min. window because it sees less than 20*f for discharge superheat....

FROZEN ALARM SCREEN IS;
CHW in+52.8*f
CHW out+ 48.5*f
Refrig. Evap Temp.+43.5*f
CDW in=79.3*f
CDW out=84*f
Cond. Refrig. Temp=85.2*f
Oil Pressure=76 psi
Oil Temp=104.2*f(same as disch temp.
53% fla

As soon as it shuts down the heater comes on in the sump as it should...but the violent boiling off of the refrigerant in there with the oil is tremendous and the level in the sump is dropped dramatically---all the while (3 minutes) the oil separator glass is completely full and gradually falls into the oil sump----after 10 minutes I checked and saw that the refrigerant must have all been boiled off and the oil that was left (out of the refrig/oil mixture that was in the separator and the sump) to a new (oil) level of bottom of the glass in the sump. (the separator now is empty.

This scenario plays out repeatedly.
Motor winding temp = 73*f
Rotor temp is 49*f

I am pretty sure none of our guys added refrigerant to this machine in the past 2 years that I have been servicing it.
I did change the oil and oil filter last year.
The eductor driers and motor coolant line drier are factory (1996 or 1999 I think)

I do know that before I had it, someone changed the oil and filter every year.

I forgot to mention recycle start alerts but I thought that may be comming from low loads (about 15 of them in the history)

But I had none of the problems I have now last year....nothing has changed since it ran last year...
Oh ---I did punch the condenser tubes in March as part of getting ready for the season.

Any sugestions....

[US Iceman]

Your problem sounds like the compressor is flooding out with liquid refrigerant.

If you are seeing the sump level continuing to drop after the machine is shutdown, liquid refrigerant is boiling off in the separator.

The other indication is the low discharge superheat.

You mentioned the machine loads up to 87% and runs for about 20 minutes then begins to cycle down.

How fast does the machine load to 87%? If the compressors load too fast, the refrigerant can violently boil and go straight back to the compressor.

How long is the machine off before it starts again and ramps back up to 87%? This also sounds like the unit is seeing some periodic load that forces it to almost fully loaded and then the load begins to disappear.

The frozen screen data only shows a 1.2 degree approach temperature on the condenser. Is this the data when the machine failed on safety or just what you observed? A 1.2 degree F approach temperature looks like a small load.

I'm not familiar with the Carrier model numbers. Is this a chiller or water cooled condensing unit with DX air coils?

[Peter_1]

Suppose these units are fitted with Carrier EEV's?
If so, we had a similar problem +/- 5 years ago and we replaced them -adviced by Carrier !! -to replace them with TEV's.
It seems that they have (had??) problems with the software algorithm.
They plugged on several times a PC to modify some settings but even then, the problem persisted.

Just a guess.
Reading psi and °F is too difficult for me because I need to translate each number in SI values :p
Just a hint post next times with SI units between brackets.

[Andy]

Hi Bradysmill:)

Welcome to RE:)

Liquid in your separator oil thats comming from somewhere

Three places I know off,

Through the suction (expansion valve, probe or flow problem)

Through liquid injection (faulty injection valve or passing solinoide)

Through discharge line (faulty check valve and or faulty separator heater)

Check all these, I would first check the oil heater, to rule it in or out.

Hope this helps.

Kind Regards. Andy:)

[Bradysmill]

Your problem sounds like the compressor is flooding out with liquid refrigerant.

How long is the machine off before it starts again and ramps back up to 87%? This also sounds like the unit is seeing some periodic load that forces it to almost fully loaded and then the load begins to disappear.

The frozen screen data only shows a 1.2 degree approach temperature on the condenser. Is this the data when the machine failed on safety or just what you observed? A 1.2 degree F approach temperature looks like a small load.

I'm not familiar with the Carrier model numbers. Is this a chiller or water cooled condensing unit with DX air coils?


Frozen screen was at a superheat shutdown after 40 minutes....
Time in between shutdowns not long because I was resetting it to try to get it on line----I only let sump temp get up to 110* or so before I started it again.....I think This machine saw some cold tower water which led to its fault on superheat when I showed up on job....Dummy me kept resseting it without letting everything get warm again, (thought disch. temp. would would come up once it loaded up) including the separator.....This probably caused the refrigerant to condense in the separator which in turn would not let my discharge superheat even attempt to come up since it will fall to 6-10 *f on startup even on a normal startup....losing battle...once things get cool.

I let everything sit for two days and started it again....I changed the ramping a little but think it was more what I described above...

Thanks for the replys.

[lldelfin67]

Hi,
They were right your unit is flooding the delta on the CHW is below Delta 6F it means that the water flow is fast and the orifice is keep on charging refrigerant to the evaporator. The approach is to low. Control the flow by having delta T of 10F to have good heat transfer on the evaporator

[jeff1465]

Hey to all of you....Just found this site and thought I would give it a try....

I have a Carrier 23XL2020EC60 FRAME 2 machine, that keeps going off on low discharge oil temp.

Arrived on jobsite to an alarm of (OILSS) oil level sensor. Oil was so low, that the level sensor wasn't made, so I added about 3 gallons to the Heater sump (probably too much....) waited till it heated up and started machine....

Oil came back eventually and I took out what I put in ...or so I thought.

Later the machine faulted on Low discharge superheat.
So I figured I still must have excess oil in the machine and shut it down....waited till the heater heated up the sump oil to boil the refrigerant off and then drained out a little more.....

Now the machine faulted on (oilSS) again.....so I added some back in......

End result is this.
1.)Startup ramps to 87%
2.)oil temp falls to 116*f
3.)Cond. Refrig. temp 93*f
4.)Discharge superheat = 23*f
5.)Oil separator is 1/3rd full
6.)Oil is leaving sump and getting lower
7.)7*f cooler aproach
8.)Evap refrig. temp= 46*f
9.Condenser refrig. temp. = 96*f
10.)Discharge superheat and oil temp always about the same.
right now is 119*f
11.)Condenser water in is 80*f
12.) Condenser water out is 88*f

Discharge superheat is not between 30 - 40*f as it should be......Will alarm if sensed after a 30 min run time (a 10 min. interval of Less than 20*f.)

After running about 20 minutes....the machine starts to ramp down....
Level comes up to completely fill the glass on the heater sump and the single glass on the oil separator will gradually fill completely also....

This happens all while discharge superheat continues to fall to about 9*f.

Unit will shut down on alarm after running for the 30 min.+ the 10 min. window because it sees less than 20*f for discharge superheat....

FROZEN ALARM SCREEN IS;
CHW in+52.8*f
CHW out+ 48.5*f
Refrig. Evap Temp.+43.5*f
CDW in=79.3*f
CDW out=84*f
Cond. Refrig. Temp=85.2*f
Oil Pressure=76 psi
Oil Temp=104.2*f(same as disch temp.
53% fla

As soon as it shuts down the heater comes on in the sump as it should...but the violent boiling off of the refrigerant in there with the oil is tremendous and the level in the sump is dropped dramatically---all the while (3 minutes) the oil separator glass is completely full and gradually falls into the oil sump----after 10 minutes I checked and saw that the refrigerant must have all been boiled off and the oil that was left (out of the refrig/oil mixture that was in the separator and the sump) to a new (oil) level of bottom of the glass in the sump. (the separator now is empty.

This scenario plays out repeatedly.
Motor winding temp = 73*f
Rotor temp is 49*f

I am pretty sure none of our guys added refrigerant to this machine in the past 2 years that I have been servicing it.
I did change the oil and oil filter last year.
The eductor driers and motor coolant line drier are factory (1996 or 1999 I think)

I do know that before I had it, someone changed the oil and filter every year.

I forgot to mention recycle start alerts but I thought that may be comming from low loads (about 15 of them in the history)

But I had none of the problems I have now last year....nothing has changed since it ran last year...
Oh ---I did punch the condenser tubes in March as part of getting ready for the season.

Any sugestions....
I just replaced the float assembly on a 23xl chiller because it had very low oil pressure and was exibiting the same characteristics that you are discribing. If you do this repair, make sure you orientate the float correctly (with the slide pin of float pointed towards bubbler tube) as it will not work correctly if you dont. Only bad part is having to reclaim all the gas and putting it back in. very time consuming.

[mileslong]

Hey to all of you....Just found this site and thought I would give it a try....

I have a Carrier 23XL2020EC60 FRAME 2 machine, that keeps going off on low discharge oil temp.

Arrived on jobsite to an alarm of (OILSS) oil level sensor. Oil was so low, that the level sensor wasn't made, so I added about 3 gallons to the Heater sump (probably too much....) waited till it heated up and started machine....

Oil came back eventually and I took out what I put in ...or so I thought.

Later the machine faulted on Low discharge superheat.
So I figured I still must have excess oil in the machine and shut it down....waited till the heater heated up the sump oil to boil the refrigerant off and then drained out a little more.....

Now the machine faulted on (oilSS) again.....so I added some back in......

End result is this.
1.)Startup ramps to 87%
2.)oil temp falls to 116*f
3.)Cond. Refrig. temp 93*f
4.)Discharge superheat = 23*f
5.)Oil separator is 1/3rd full
6.)Oil is leaving sump and getting lower
7.)7*f cooler aproach
8.)Evap refrig. temp= 46*f
9.Condenser refrig. temp. = 96*f
10.)Discharge superheat and oil temp always about the same.
right now is 119*f
11.)Condenser water in is 80*f
12.) Condenser water out is 88*f

Discharge superheat is not between 30 - 40*f as it should be......Will alarm if sensed after a 30 min run time (a 10 min. interval of Less than 20*f.)

After running about 20 minutes....the machine starts to ramp down....
Level comes up to completely fill the glass on the heater sump and the single glass on the oil separator will gradually fill completely also....

This happens all while discharge superheat continues to fall to about 9*f.

Unit will shut down on alarm after running for the 30 min.+ the 10 min. window because it sees less than 20*f for discharge superheat....

FROZEN ALARM SCREEN IS;
CHW in+52.8*f
CHW out+ 48.5*f
Refrig. Evap Temp.+43.5*f
CDW in=79.3*f
CDW out=84*f
Cond. Refrig. Temp=85.2*f
Oil Pressure=76 psi
Oil Temp=104.2*f(same as disch temp.
53% fla

As soon as it shuts down the heater comes on in the sump as it should...but the violent boiling off of the refrigerant in there with the oil is tremendous and the level in the sump is dropped dramatically---all the while (3 minutes) the oil separator glass is completely full and gradually falls into the oil sump----after 10 minutes I checked and saw that the refrigerant must have all been boiled off and the oil that was left (out of the refrig/oil mixture that was in the separator and the sump) to a new (oil) level of bottom of the glass in the sump. (the separator now is empty.

This scenario plays out repeatedly.
Motor winding temp = 73*f
Rotor temp is 49*f

I am pretty sure none of our guys added refrigerant to this machine in the past 2 years that I have been servicing it.
I did change the oil and oil filter last year.
The eductor driers and motor coolant line drier are factory (1996 or 1999 I think)

I do know that before I had it, someone changed the oil and filter every year.

I forgot to mention recycle start alerts but I thought that may be comming from low loads (about 15 of them in the history)

But I had none of the problems I have now last year....nothing has changed since it ran last year...
Oh ---I did punch the condenser tubes in March as part of getting ready for the season.

Any sugestions....
Does the machine have hot gas bypass? I just had the same issue at one of my accounts. Try shutting off the hot gas bypass valve and see if that helps. Also, dont add extra oil to these machines, the extra oil has a tendancy to get entrained in the evaporator and then into the screw which makes for a very noisy machine. There is other ways of getting the oil back besides adding extra. The machine will take a little liquid in the oil as it has roller bearings which do not need massive lubrication to function correctly.