York YK has my attention

[hw chiller man]

I have witnessed thin ice forming on the flange going into the evaporator of this particular chiller. I have six of these chillers on this site and have noticed this to varying degrees on 2 other chillers. These chillers have the variable orifice condenser level control valve. There is no ice on the 4 inch line directly downstream of the level control valve but only on the flange. The SST is 37.9F and the suction pressure is 33.3. The pressure was confirmed. My question: is there another fixed orifice sandwiched between these two flanges. The insulation immediately around this flange leading into the bottom of the cooler was removed and no freezing takes place here. All thoughts would be appreciated. Other readings are CHWS 46.9, CHWR 38.2, CWS 74.6, CWR 83.6, Discharge temp 109.3, liquid line temp 82.

[mdp]

One thing seems to glare out at me, the 38.2 CHWR temp. Why so low? What application are these machines in, comfort process? Doing some basic math, to get a 38.2 CHWR temp you're going to have temperatures below freezing note the suction presure of 33.3. Hope you're running a glycol mixture.

[hw chiller man]

This particular plant manufacturers minivans and this chilled water is used for paint process cooling. It is a decoupled system with many design deficiencies which necessitate 38F chilled water (not glycol) to overcome. Very high loads this week caused the system (6 - 2000 ton YK's) to be run at maximum conditions. This particular chiller was surging . I ended up removing approx 2000 lbs of R134A to get it to settle down and still my evaporator approach never changed at approx 2F. The SST was approx 36F with 38F leaving chilled and the ice dissapeared. The chiller is running good at this time. Thanks for your reply MDP. I will continue to monitor this particular chiller and spend some time setting up the level contollers on all the chillers which I believe have been neglected by the previous service company.

[absrbrtek]

What was your discaharge SH at full load?

[hw chiller man]

I have not been able to get the chiller to full load. The operators prefer to run all chillers at part load conditions rather than running say 4 chillers at full load. I don't have the luxury of "experimenting" to ramp any particular chiller up to 100%,because it is a manufacturing facility and I cannot start and stop chillers. If I recall on Friday this chiller was running at 70% load with approx 110F discharge temp, I can't remember what the discharge pressure was after removing the refrigerant but I was able to refer to my logs done earlier in the week with the chiller running at 45% and the superheat was approx 25F.