Rotating Stall on a York YK

[man from trane]

This is a 750 Ton machine, designed for 32°F Brine LWT, 56°F EWT, serving a manufacturing process. It is equipped with Solid State Starter, VGD, and HGB. Here's what happens:
The process drops off to nothing, EWT falls to the 32°, (LWT setpoint is 32°) the PRV closes, and the compressor enters stall conditions. The VGD moves to its full stall-prevention position, but as there is no refrigerant moving it doesn't seem to help. It will stay in stall condition forever. Discharge temp rises to around 167°F! The VGD counter is already infinite at 999,999 and the other window (I can't remember what it was called) is at 74 days. This machine is very new and it's possible it has only been running for 74 days. Once in a while the process picks up and the machine comes out of stall. Also, if I manually open the HGB it comes out of stall.

Why doesn't the HGB open by itself? Or why doesn't the machine pull down to 29° LWT and shut down? This is a new plant so they are having production issues and that is why there's often no load.

[klove]

Is the hot gas enabled? What are the settings? Is it calling for it and it's just not opening? Could be bad component or bad setup. We're guessing with the info given.

Turndown on the machine is such that once the vanes are closed there's not enough capacity vs. load to drop to low temp cutout.

Have this moved this to the pro forum.

[YMC2]

hi

funtion of HGB is prevent surge and minimun charge , first set point hgb , is the return temperature , please set point chiller in temperature 34 f , and band dead 6 k , hgb on for return temperature is 34 f .

the stall , please calibration optiview vgd screen , in maximum sensibilities surge reac, 1 seg, prv 0%, wai... 15 min , pulse 1 seg, lim low 0,4 , lim high 0,5 .

you voltage the transducer pulse vgd , calibration low and high lim.

lucky for yk supreme chiller.

[man from trane]

I saw the hot gas open once, so I know it's enabled. It's set for 1°, and I don't remember the other settings. I tried changing the settings and nothing I did other than using the manual override allowed the HGB to open. I'm going back tomorrow so maybe I'll take a screen shot from the Optiview. But if there's no capacity once the vanes are closed then they're screwed. They're just going to have to actually monitor these chillers and shut them down once the load drops off. But they have two other larger YKs, 2200 tons each, running at 60°F for another process. The cooling tower also feeds that process so if the ambient is low enough there's no load on those chillers. The LWT gets lower and lower, HGB opens to 80% (its max setting), and eventually they shut down automatically. The HVAC and 32° chillers don't do that. The HVAC chillers have no HGB but have VSDs, and they just sit there and surge until the load increases. What a bunch of crap. I've never had these issues with CVHEs. They just pull down and shut off if there's no load.

[man from trane]

I don't get some of that, and some of those setting don't appear to exist on the screens I've looked at. One thing is for sure, I don't consider myself lucky because these things are supreme pieces of crap. I did attend a YK class at York but they didn't go into a lot of detail.

[KnewYork]

One thing is for sure, I don't consider myself lucky because these things are supreme pieces of crap.

In general, comments such as this indicate one of two things...lack of knowledge or a supreme desire to get no help from those who might be able to help.

As for YMC2, I think what we here is a failure to communicate.

[york56]

[jayguy]

...One thing is for sure, I don't consider myself lucky because these things are supreme pieces of crap...

i understand how you feel. i worked for trane for 11 years before working for jci (everybody keep your comments to yourself). i, too, felt that york had some backward ideas but there were somethings that were (and are) way better than tranes way of doing things. some trane ideas are better than yorks. the cool thing, is that as i learn more about the york stuff, i can incorporate BOTH into a much better understanding of chillers...way cool. look at the equipment as a challenge and you will be the hero in your customers eyes. if you don't, then I may be the hero in your customers eyes!

[klove]

I don't understand why the YK is a piece of crap because it has a better turndown than a CVHE. Granted, there are things about the YK's that I'm not to keen on, but the same can be said of anything that Trane, Carrier, McQuay, or any other manufacturer builds. Like KY said - it's all in what you're most familiar with. I also have a hard time understanding how you blame a machine for matching the load placed on it any more than you can blame a dog for pissin' on a fire hydrant - he's just doing what a dog does. Sounds to me like you have plant and/or design issues more than you have chiller problems.

So stop complaining and get in there and tweak the settings on the HGB to find a good place to run when unloaded. And if you're going to run for hours on end at 0 load, you better have liquid injection on the bypass system...

[man from trane]

I'm sorry, but from my point of view any chiller that doesn't have the built-in smarts to shut itself down when there is zero load for hours or even days, but rather goes into self-destruct mode and consumes untold amounts of precious energy resources while doing zero work is unacceptable. I will admit that I am quite ignorant about the YK chiller aside from a 3 day class at JCI, but this just does not make any sense to me.

According to the York Service Manual, the HGB is not going to even attempt to open until a SURGE is detected. My surge counter is -0- with a sensitivity of 0.3, the greatest sensitivity setting. So it's doing what the programmers told it to. Surging is not an issue. I see no provisions for getting the machine out of a STALL except for closing the VGD, which it does. But closing the VGD with the PRV at 0% is apparently useless.

Talking to the process guys at the plant today, this machine cools storage tanks in the summer, cools a single small process machine, and cools warm product during transfer once a day. It's winter now so the tanks don't need cooling. The process produces almost no heat, so basically the machine loads up for an hour once a day and is stalled the other 23 hours.

So exactly what HGB settings would I "tweak" to get the HGB to open when there is no surge present?

Maybe I should put a Honeywell T7775 controller on the HGB actuator with a thermistor on the CW supply line.

[jayguy]

a cvhe with a hgbp will do the exact same thing. it will open up and produce no net-cooling for as long as it can. i have seen it and they are a pain in the butt. i understand that the chiller may not be energy efficient at this time, however, you said yourself that there isn't any real load. if you put a prius motor in a dump truck, do you blame the dump truck for not getting high fuel efficiency?

[klove]

Talking to the process guys at the plant today, this machine cools storage tanks in the summer, cools a single small process machine, and cools warm product during transfer once a day. It's winter now so the tanks don't need cooling. The process produces almost no heat, so basically the machine loads up for an hour once a day and is stalled the other 23 hours. Sounds like you have an answer to your problem. Since you have a control room and control personnel, turn the chiller off if it's not needed. This can be done with a light switch at the operators desk. No need for a fancy automated system.

Maybe I should put a Honeywell T7775 controller on the HGB actuator with a thermistor on the CW supply line. In certain situations, I've done just that (or something mighty close). Sometimes it's up to the guy in the field to suggest and implement the fix. As Hawkeye Pierce said, "You can't get a custom fit in an off-the-rack-world", and you have a package chiller, not an engineered refrigeration system. There's a huge difference.

.

[man from trane]

Here's what I want, and given the capabilities of the Optiview controller I don't think it's too much to ask. Either A: give me a minimum capacity limit such as 15%. This will be enough to drive the LWT down to the disable setpoint and cycle the machine off when the load goes away. Or B: when a stall is detected and the VGD is closed for 30 minutes, modulate the HGB open to eliminate the stall. Why can't it do that?

Another oddity: the 2200 ton YK chillers at the same site continue to pull down when the load goes away, and then they cycle off. Is it because they are designed for a 60°F LWT?

Efficiency is a concern, but I'm more concerned about the compressor self-destructing. It sounds like a large steam engine and runs 104°F discharge superheat. That can't be good.

[jayguy]

how about just disabling the hot gas bypass valve feature? that would drive the chilled water temperature down and should shut the chiller off from the sounds of what you have.

[YMC2]

men, please call YORK_JCI foreman technician , YK 2200tr chiller not is device scholl, you problem is very hard.

[klove]

Here's what I want, and given the capabilities of the Optiview controller I don't think it's too much to ask. Either A: give me a minimum capacity limit such as 15%. This will be enough to drive the LWT down to the disable setpoint and cycle the machine off when the load goes away. Or B: when a stall is detected and the VGD is closed for 30 minutes, modulate the HGB open to eliminate the stall. Why can't it do that?

Another oddity: the 2200 ton YK chillers at the same site continue to pull down when the load goes away, and then they cycle off. Is it because they are designed for a 60°F LWT?

Efficiency is a concern, but I'm more concerned about the compressor self-destructing. It sounds like a large steam engine and runs 104°F discharge superheat. That can't be good.

You want an engineered control system. So do the rest of us in any odd situation we find ourselves in. You're not going to get it. There's things about Tranes that stink, too. If it would do what you want, it would sit there and beat the rotor bars in the motor and the journal bearings into scrap metal from excessive starts. I've personally witnessed this on more than one process chiller.

This is not a chiller problem from what I'm hearing - this is a problem of system design and unwillingness by men to shut the machine off when not needed. It's the little brown, double-ended switch at the bottom right of the keypad. Turn it off.

You're right, it's not good to run under the conditions you describe. Turn it off.

The 2200 TR's load is going away completely and the smaller units load is only dropping to the same point as the idle system capacity of the chiller. Turn it off.

[jayguy]

how about just disabling the hot gas bypass valve feature?...

sorry. i just remembered today that you said the hgbp valve is not opening as you suspect so this idea is moot.

[man from trane]

No, BOTH machines' load is going away completely. The 2200 pulls down and shuts off. The 750 just sits there and runs. I shut the chiller down for 30 minutes and the water (brine) temps stayed at 32°F. That's how I know there is NO load.

[man from trane]

So I guess the consensus is they're just going to have to shut the machines off when there's no load. So why in the world did York even provide a Disable Setpoint?! What could this possibly be used for if the machine can never reach setpoint - 1°? The only thing I can think is if you have multiple chillers on the same loop and another chiller has a lower LWT setpoint. But I only have one chiller (for now, they're going to add another) so I'm screwed.

So, how long can this thing surge like a locomotive before the compressor is toast?

[KnewYork]

If any thread needs to be in the PRO FORUM, this is it. There is no way a technical conversation as deep as is warranted here should be in the open forum.