Liebert HP

[slavex]

Hi,
Problem with Liebert CCU with water cooled condenser and free-cooling .
On first start, compressor go on Hi pressure(25bar.). After reset alarm, compressor starts and work without problem. I can switch on/off compressor several times it will work without problem, if compressor is off longer, on next start compressor will go on HP alarm.
Any suggestions, is it problem in head pressure valves or...

[stufus]

Are your water pumps going off too??
Cheers
Stu

[slavex]

No,
water pump is always on,
water pressure - ok,
water valve -open
amount of refrigerant-ok
ref.valve-open
only first start of compressor is problem, after that unit can work all day without problem.

[install monkey]

expansion valve may be causing issues as it can take a few minutes to stabilize

[slavex]

i have head pressure valve after compressor on hi pressure side, his function is to open bypass from hi to low pressure side to, balance hi pressure on compressor start.
correct me if i'm wrong.

[slavex]

any suggestions, how can i solve this problem, please.

[Alan.D]

any suggestions, how can i solve this problem, please.

Is there a ball valve and actuator on the water line?

[slavex]

yes there is, but i disable free cooling so valve is closed and all water flow goes true condenser

[install monkey]

is the strainer on water circuit clear?

[install monkey]

liebert units have a head pressure control that regulate and if req inject into liq receiver- try adjusting it to allow more into the condenser

[RusBuka]

Where you take water? Drycoolers? What temperature outdoor?

[slavex]

is the strainer on water circuit clear?

yes strainer is clear, only first start is problem after reset compressors work perfectly.

[slavex]

liebert units have a head pressure control that regulate and if req inject into liq receiver- try adjusting it to allow more into the condenser

yes there is head pressure valve LAC 5-with fixed pressure of 180 psig. i think it is can not be regulated.

[slavex]

Where you take water? Drycoolers? What temperature outdoor?

in drycooler, outdoor temp. 10

[install monkey]

whats the hp switch set to trip at and does it trip at the stated pressure?

[slavex]

hp switch is set on 26 bar-i caught that pressure several times, so alarm is real



sorry if i don't understand your question properly

[RusBuka]

have you check valve or solenoid between discharge pipe and water condenser? And have you any valve after condenser?

[install monkey]

what make , model is the head pressure control?- usually they have an adjusting screw, can it be swapped to prove it works?

yes there is head pressure valve LAC 5-with fixed pressure of 180 psig. i think it is can not be regulated.

[slavex]

there is cpce valve on discharge line nothing else.
and after condenser- lac-5, one way valve liq.receiver, filter,solenoid, exp.valve. I switch solenoid on always to eliminate it.

[slavex]

what make , model is the head pressure control?- usually they have an adjusting screw, can it be swapped to prove it works?

http://www.legacychillers.com/cms_da...oodedvalve.pdf

[install monkey]

is there another unit on site you can compare pressures,temps,running current? when the system stops when at setpoint liquid isn't flooding the evap so upon startup it trips?

[slavex]

yes i have another unit, same model,pipe length, water pump, pressure ...it is working without problem.

if compressor stops at setpoint and after short brake start up again it will work without problem, if there is longer brake next start is always with HP.

[install monkey]

is there any settings on the controller or a delay timer that ignores the pressure switches on start up - may req increasing

[RusBuka]

how long it takes from start to crash, where there is a high pressure? something is blocking discharge at the first start.

[slavex]

is there any settings on the controller or a delay timer that ignores the pressure switches on start up - may req increasing

pressure switch on 26 bar cut off signal and i have to restart switch manually, i thought that i can put new switch set on 28 bar, but is big risk because i have safety valve on 30 bar.