chiller oil level

[kerrcell]

I have been on a chiller that found oil level very low tripping on low oil .Recently someone has removed compressor for rewinding and reinstalled.Now I find that there is low oil level.I tried to pump down circuit to try and get the oil back in cranckcase but to no avail.There is no oil.So where did the oil go ? I cannot just topp it up to the right level and leave.On the other hand feels like it's better they call in the one that removed the compressor. I don't know what to do.The system is on R22 and the compressor is reciprocating.Any idea

[gregd1401]

Add just enough oil to maintain oil pressure and get a decent run from the chiller. If the oil returns you may have to remove some. If it doesn't come back, top up oil to correct level in sight glass. Keep monitoring until you are happy with oil level.

[kerrcell]

Yes actually what I did was topped up with a can full and still sight glass is empty.I can top up more but where does the oil is going ? What I am doing is not solving the problem,escpecially when the compressor was onerhauled very recently.I need to solve problem of oil.Can it be is being burnt ?

[gregd1401]

I don't think it would be being burnt. Probably being trapped inside the chiller vessel. Was the compressor rebuilt properly. I would suggest you carry out a pump down test of the compressor or maybe even pull the heads off and look for any damage. Just out of interest, what make and model of compressor.

[gregd1401]

Just realised you said compressor was rewound. Was it rebuilt at the same time? If not could be a real problem.

[kerrcell]

As I told you before,it was not me that have removed compressor from place.Actually it was dismantled taken to a workshop and send abroad for repairs.Then reassembled back.What I find new is that they installed a suction cartridge filter with replaceable core.I suspected in this,is there any that can cause oil restriction here? But there is no suction drop in pressure.Even when I tried to pump down system ,the suction does not go belo 10 psig since there is the microprocessor and stops the unit.The chiller is microprocessor controlled.When I added oil,have disabled oil pressure control otherwise could not have let me time to add.I shall ask also here how can I add oil in another way as it takes lots of time.

[Sandro Baptista]

Try to keep the compressor at 100% capacity and with high suction pressure during 10 minutes. Ensure a good water/glicol flow on the evaporator with some high temperature.
That would help to bring back the oil stucked in several parts of the circuit. Also I know that this could be crazy but try to purge some oil and insert some POE oil.

Then tell me about it.

[kerrcell]

Sandro,
The oil history is that initially the tech used suniso,worked for a week and drained all.Then filled with virginia mineral oil 150 (iso 32).The system uses R22.I check for poe specifications and is more used for R12 and R134A.I don't know what to do.Client is worried as he has paid money to overhaul compressor.From my side don't want to try thing that will end up badly.Has the other tech work well using mineral oil ?

[Sandro Baptista]

You are right about the use of mineral oil with R22 however you could also use POE oil for HCFC gases (f.e. R22). POE is a good solvent and could help you to bring you up the mineral oil.
Is the compressor at 100% and with a high evaporating temperature as I told you before?

[gregd1401]

Can you please tell me the make and model of compressor.

[moideen]

may be wrong overhauling.chek oil ring ang oil return check valve.also chek suction cartrige filter and liquid line filter.

[kerrcell]

The system is used for heating mode so at the moment the condenser is reversed to be an evaporator.All three fan motors are running at high speed.Also there is no oil check valve as it is something internally.What I still have to check is to remove the suction filter as for me this does not make sense once the system has been running for quite some time now.I should remove the filter core now in opinion.With regards to the liquid line filter,if there is a blockage will surely read a drop in pressure as well as feel the filter drier cold to the touch.This is not the case.When I tried to maka a pump down and removed the liquid line solenoid to produce such,the pressures change accordingly.

Getting again to the oil type ,you mention poe,shall I just top up the remainder or has to drain the oil that is contained insump ? Later will send the details of the compressor.

[kerrcell]

compressor is copeland D8SH1-5000-BWM-D R22 gas

[Sandro Baptista]

Getting again to the oil type ,you mention poe,shall I just top up the remainder or has to drain the oil that is contained insump ? Later will send the details of the compressor.

Just for ensure the best oil return I would empty oil that is contained in the sump. About the remaining mineral or AB that is on the system don't hurry about it...sure it come back to the sump. However it is still very strange why the oil is not coming back with the R22. Have you sure we stiil have R22 gas and not a drop in or something like that?

[old gas bottle]

slightly worreing that you have added a quantity of oil and as you say there is still no oil !!

its not overfull is it ?, drain it all out and then fill it half way up the glass, run it and see what happens then ajust the level after a couple of hours.

if it just looses it,there may be a problem with the oil sep if it has one or even the rebuilt compressor.do the oil first

[chemi-cool]

adding more oil is typical mistake.
Is there any oil leak? I guess not.

I can imagine there is no oil trap on the discharge line.
Oil can be in condenser [heating mode] or evaporator.

From my experience, increase the SH a little bit. That would cause the refrigerant to flow faster and bring it back.

If there is a suction filter, remove it, its useless after the first working week.

[That's too cold]

DO NOT ADD ANY MORE OIL!!!

1. Does it have a "oil separator" in the discharge line between the compressor and condenser coil?
2. If the system is "low on charge" it also will stuck the oil out of the compressor until it trips the oil press switch.
3. Does it have any type of "oil management controls"?

[Sandro Baptista]

From my experience, increase the SH a little bit. That would cause the refrigerant to flow faster and bring it back.

I don't agree the refrigerant will flow faster. The volume sucked of the compressor will be the same so the velocity will be the same. Also for the same operating conditions the gas density will be lower and the mass flow will be lower.
The SH will be higher because you will open less the thermostatic expansion valve. However higher SH will prevent liquid enter the compressor that would influence the steady of the oil on the sump.

[kerrcell]

HI Guys,
First of all many thanks for all involved in sending their views.I appreciate it.Well at this stage did not top up with oil since the last time I sent,before going to the client need to go with a solution.Between the discharge and the condenser coil there is no oil separator.Also there is no visible oil leakage around.The system at this time is running for heating mode.Shall I try to change to coolinf and try several pump downs to try and draw back oil if it is trapped somewhere ? The oil has a control on the microprocessor.The circuit is tripping obviously on low oil pressure.I have also opened up the sight glass to be 100% sure that it's not full,because sight glass from inside was dirty and was not 100% about it.I will surely next time go on site will remove the other technician's suction filter.I think there is an onbstuction that has non sense there.

[alan wolf]

Hello
Heat pumps can accummulate a lot of oil in the condenser (evaporator when on heat mode) and York had a retrofit on AWHP types which took 1/4 lines thru solenoid valves back into suction close to compressor. Oil pick up point was at bottom of headers of air cooled condensers.
AWW

[Sandro Baptista]

If you (kerrcel) invert the circuit just for a half of hour it would could be checked.

[serviceman]

sandro: a bad return for oil could be:
oversized expansion valve or poorly calibrated
low temperature in the evaporator
check valve oil return in poor condition (compressor)
Inverted oil rings

[alan wolf]

hello

the suggestion to try run unit on cooling to see if oil returns I feel is a good 1 as oil in system should return.
if so my earlier suggestion of oil hanging up in the condenser may be valid. expansion valves also need to be checked as well as check and driers.
AWW

ps oil should return easily via shell and tube evaps with gas thru the tubes, a flooded evap is another problem. what type of unit is it?

[CHILLAIRE]

Hi to all I'm just new but i hope this will shed some lights to the problem of Kercell if ever it is unresolve yet.
Recip compressors has an oil check valve between the motor and crankcase. This valve should open to allow the oil to flow to the crankcase from the motor. If it stucks, oil will stay in the motor and crankcase oil level will drop until OPS trips-off. Failure of the valve to open could be caused by blow-by creating pressure in the crankcase and closing the valve.

[kerrcell]

Chillaire,I will be on site again in the coming week,first of all thanks also including all other's reply.Well you are suggesting a problem internally of the compressor.If it's that problem better ask client to recall the tech that did the overhaul!But will try and do a pump down first on cooling mode to see if there 's any luck and oil gets collected back in cranckcase.Will try alan wolf's idea,which to me is good worth trying and will also remove if there's still the filter core in the suction.

[daniel25486]

Hi everybody, is my first post reply.

Even so the date of this thread being old, I feel i have to say something about this.

kerrcell, its obvious that comptessor Copelang D8SH had in the past a burn out, so some AC company out the suction filter. This filter is temporary, you have to make oil analysis until the oil is in good condition, after you can take out the filter.

If the oil is in no good condition the mixcibility with R22 will be bad, and so that the oil will be trapped in low points, suction acumulators, etc.
In my opinio what you have to do is take out the R22, purge the system with nitrogen separately ( discharge line, liquid line, suction line, suction acumulator, etc, You have to take out the much oil you can from the circuit.
After this make a good vacuum and use it to put the oul in compressor by the oil service valve, fill it until 50% of th sight glass, that correspond to maximum level of oil for that compressor.
Insert the full charge of R22, or a dropin (R422D, or R404/R407C but with a good cleaning device- see other threads about this theme). That put the corresponding circuit working for 48 hours, its normal the sight glass drop a little bit, but not to much, it should go to 1/4 of sight glass. after this 48hours check the oil with an oil analyser test if its nogood make another oil change, if not, you have to have in mind this situation if the oil is no returning to compressor its because your compressor has an capacity solenoid, the best away to solve this situatuion is to dehactivate this solenoid, just take it out, this is a common problem with all reciprocating compressors ( the lines are designed for 100% working not to 25 or 50 % - loss of velocity).

Another situation is the pump down is very important to oil return, but you only can make a pump down in coolling mode; check this out in pump down you recover almost all refrigerant to condenser in cooling mode; the volume of shell and tube is smaller than condenser, than if you recover all refrigerant to shell an dtube the perssure inside the heatexcanger will increase and it probaly trip the safety discharge valve (12 - 15 bar).
Also the oil return in heating mode is badly beacause the evaporator has now a bigger volume, and if you are workin gwith capacity steps in that type of compressor will even more badly.

Sorry for my ortographic and grammar mistakes.

If you have opinions of this post please freely respond it.

[finkel]

chillaire is right,had the same problem after rewounding.Oil check-valve was stucked by product they use for isolation of the wounds