chiller HELP

[tchc]

I am working on a York liquid screw chiller. The oil pump and filter were changed prior to my arrival.
Unit continues to trip on low suction pressure.
There was a large amount of metal shavings on the old filter and magnet.
I have a 4 to 5bar drop in oil pressure in the compressor. Is the pressure drop the cause of my low suction pressure. And advice on what step to take next. The unit has appr 750 operating hours.
Upon start up I manually adjusted TXV to 15-20% and slide valve to 10%. At one point the unit was running for a few minutes, when i adjusted the TXV it trip on low suction.
Im lost!

[Magoo]

Hi tchc.
I am familiar with the machine, but do not like the fact that oil pump and filter were changed and had metal filings in filter. Something has seriously ground up somewhere. The fact that the compressor trips on LP suggests no liquid feed to evaporator, possible blockage in liquid filters. The 4 + bar delta p oil also suggests another blocked oil filter.
Could be time for a total re-build.
For the short period when compressor runs, does it sound happy.

[tchc]

Hi Magoo, thanks for getting back to me.
Yes when the unit runs its sounds good (if you like the scream that they make).
After all checks were made we did in fact change the oil filter again. When we did so the unit still tripped. I suggested to the York tech that we may be low on refrigerant(134a) as the other units site gauges were considerably higher. We added a small amount( he didnt like my suggestion so did half heartly), we we did the unit kicked off and ran, it ran good for 1 to 2 minutes when the York rep went to adjust the TXV the unit tripped off on low suction press once again.
Also there is still a restriction somewhere, seems like it might be in the compressor, oil return line is lower then what the compressor oil press gauge reads. The reading is taken after and prior to the oil filter.
Please help

[Magoo]

Hi tchc.
The scream is normal but without growly glangy noises.
If oil filter changed and clean, then possible pressure transducers are giving false reading to processor, so not letting compressor load and opening liquid feed vav to evaporator, but still check the liquid feed filters and strainers. factory techs don't like to be told how to service there equipment, keep that in mind OK. If system is operating differently than others on site, pressure wise, then there is an anomoly somewhere. So be persistant with York tech..
Remember system balance, there is something in system that is telling you that it not happy. The metal particiles still worry me.
keep in touch.

martin

[tchc]

hello Martin.
Thanks for the advice.
The York rep is not real helpful and doesnt seem real confident with this particular system, he admitted he is land based not marine.
Where are the liquid feed filters located, the only other filter i see is the filter drier prior to the txv, I did ask if there were any screens on this system and he sounded sure when he said no.
And yes i am very cautions with my suggestions to the york rep. I have alot of experience in the HVAC field, just not on the big tonnage chillers, I to remember people always trying to give me advice (hated it), there is a slight communication barrier though, he is swedish and I am amercian. I think he really understands english all that well, enough to get by.
Thanks Sean

[Magoo]

Hi tchc.
the liquid filter drier/ screens will be the ones before th TXV's, normally if partially blocking you could feel a temp difference from in and out, but seeing your machines runs for short periods, you will not get that indication. Never mind. Pump the system down and check anyway.
Still worries me all that junk in the oil filter.
OK Swedes are out going with info., take that as given fact.
Suggest that you will cancel his exit visa until the system has been sorted, and you will get a very freindly and supportive Swede.
Martin

[goshen]

HI there when the unit ran what were the pressure readings did u check for leaks ?
if u want a schematic of the comp mail me
gill@gosheneng.co.il i will try 2 send it
so far seems like magoo is taking great care of u
good luck!!!