YORK Millenium Recip chiller

[exxu]

Hi guys
My problem with this york controller is that the low pressure alarm is set to 3,31bar and the water temperature required (set point) is 5 C (R407c).
The unit trips in LP when the water reaches about 5,5 C.
So i need to change the low pressure alarm set point to 2,5 bar. This parameter's value can't be altered from the PROGRAM menu.
Any ideas ?

[james10]

is the unit designed to run that low? perhaps if you could provide the model we could help out a bit more

[exxu]

I found a operation manual for this controller.
The chiller is set now to "Water cooling". This means that the low pressure alarm is set by the controller to 3,3 bar and this value can not be changed.
But if i can set the chiller for "Glycol cooling" i can modify the lp alarm value.
So my question now becomes: how can i set the chiller to glycol cooling ?

The model is LCHM 140 AL 50E.

[goshen]

I found a operation manual for this controller.
The chiller is set now to "Water cooling". This means that the low pressure alarm is set by the controller to 3,3 bar and this value can not be changed.
But if i can set the chiller for "Glycol cooling" i can modify the lp alarm value.
So my question now becomes: how can i set the chiller to glycol cooling ?

The model is LCHM 140 AL 50E.

Hi:
if you have the right manual page 8 use options to change to brine control!!

[exxu]

Hi:
if you have the right manual page 8 use options to change to brine control!!

It seems i don't have the right manual.
A little bit of help ?

[al]

before you set to glycol you really would need to put in glycol, if the system is tripping on low suction at 5.5c what are your pressures?

Suction
discharge
subcooling
superheat
% loaded compressor
water pressure in
water pressure out
water temp in
water temp out

it sounds like you may have low water flow, changing the lp setting may not be the answer, although 407c can be a bugger for nuisance lp trips.

alec

[Dennis1977]

Hi exxu just a question how come you are tripping at 5.5C if your LP is set at 3.3Bar which is more or less -4C Saturation temperature? Because 5.5C is almost 4.5Bar in the PH chart of 407C and as you say the water temperature set point is 5C. Is this means that your LP trip is higher than your water temperature set point? Can you please check your water temperature sensor may be it is faulty.


Regards

[exxu]

Most of the time the system runs ok.
But now and then, it trips in LP. Indeed it seems that the water flow decreases sometimes for about 1 minute because of the process (it is use in process cooling) and the chiller trips making the production to stop.
We can't control these flow fluctuations so the best thing to do is to set the chiller to glycol cooling, set the LP alarm to about 2,5 bar and the minimum leaving water temperature to the same value that it is set now: 3 C.
If i do that, the chiller won't trip in Lp in that minute and would be protected from freezing by the 3 C setting of minimum leaving water temperature.
The sensors are ok.
Thank you for your replies.

[Magoo]

You have answered your own question, the fluctating flow is the real issue that has to be resolved. The system is protecting itself from blowing a heat exchanger tube or plate.
Suggest a by-pass flow regulator that maintains flow rates, so normal controls can control system and cycle off system.

[yorkman_gr]

I will suggest don't touch the dip switches, the only safety u got in this chillers are you LWT sensor and your low suction cut out set point, check all the suggestion that they engineers did and ASAP check your flow, a good DP for York chillers is about 60 KPa, between you inlet and outlet water, and try to create a constant flow across your evaporator, don't mess with the settings because if u do you are looking for serious troubles

[Grizzly]

As the other guys have suggested.
You are trying to run to close to a freeze up situation.
Try and remedy the fluctuations in flow as Magoo has suggested.
Grizzly

[exxu]

Today we solved the problem. It seems that a couple of their machines were using 2 way valves instead of 3 way valves. The flow is now ok and the chiller works fine :
Water DT=4,8 C,SH=6k, SC=8k.
Thank you again for replies.