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hot gas will open up at 1 degree below leaving chilled water set point unless you set it to 2 then it will be 2 below set point and so on....

That might not be out of the question!

Originally Posted by klove

I'm not with York anymore (never did consider myself to be with jci), but if you'll get me a PO I'll come to Omaha and show you how. I'm not cheap, but I'm easy

i am 2 hours from omaha...1:30 if there aren't any cops!

This entire discussion is explained in great detail in IOM 160.54-m1 this thread should be in the pro forum.

Originally Posted by man from trane

I would like to see the JCI tech get it to cycle off. Are there some hidden parameters I can't see from service mode? Even the service manual says it's doing what it's supposed to by not opening the HGB unless there's a surge condition. JCI won't be coming back here unless there is a major issue that we can't handle. That's why I would like to be able to correct this without getting them involved.

In another part of the building there are (2) smaller YK chillers used for HVAC that also do not cycle off. But they will sit and surge rather than stall.

I'm not with York anymore (never did consider myself to be with jci), but if you'll get me a PO I'll come to Omaha and show you how. I'm not cheap, but I'm easy

I would like to see the JCI tech get it to cycle off. Are there some hidden parameters I can't see from service mode? Even the service manual says it's doing what it's supposed to by not opening the HGB unless there's a surge condition. JCI won't be coming back here unless there is a major issue that we can't handle. That's why I would like to be able to correct this without getting them involved.

In another part of the building there are (2) smaller YK chillers used for HVAC that also do not cycle off. But they will sit and surge rather than stall.

Originally Posted by man from trane

No one ever answered my question about why the machine has a Disable Setpoint if it is incapable of making chilled water colder than the setpoint. Why not just have a single LWT setpoint and leave it at that? It never cycles off no matter what.

The chiller you have was selected by someone to perform a certain function. We don't know how or why it was selected. I will guarantee you that any of the former York (or present JCI) guys who frequent this site could get that machine to behave (and shut off). A thorough understanding of the various components and programming of the Optiview panel come into play when a machine isn't performing. You aren't dealing with a standard comfort cooling machine like those old CVHEs. Yorks will cycle just like those CVHEs when applied in a comfort cooling application. You have a more complex system and the system (outside the chiller) isn't doing what its designed to do and you're blaming the chiller. You even stated in your original post that they are having problems with their process.

In the late '90s I ran a plant with (2) 750 ton Trane Centrivacs. Sometimes the load would drop off when the outside temp fell suddenly and the AHU's started running mixed air. I'd sit there in the engineering office and hear the lead machine cycle off. If the LWT came up after a while it would restart. What a concept. Those chillers had no bells or whistles. No Variable Speed Drive, no Solid State Starter, no Hot Gas Bypass, no Variable Geometry Diffusers, no Optiview, actually a very simple design. They're still running to this day, years later and the only time I ever heard one surge was if the condenser water went above 86°F. Then all I had to do was raise the CW Setpoint a bit. I never even knew what a Rotating Stall was until I encountered these YK machines.

Maybe the YK is a great machine. Maybe they are misapplied at this plant. I don't work on centrifugals often, but I would think in 20+ years I would have encountered this problem on other machines but I have not.

No one ever answered my question about why the machine has a Disable Setpoint if it is incapable of making chilled water colder than the setpoint. Why not just have a single LWT setpoint and leave it at that? It never cycles off no matter what. And since my name is on the log it is very relevant to me if a 6 month old compressor shells out.

Originally Posted by KnewYork

Not a very good idea when there is no load. The thing will cycle itself to death as pointed out earlier.

Op said it spent 30 mins at 32 degree return with machine off. If that's true why couldn't you shut down at 32 an bring it on at 40 or more? Wouldnt that be better than leaving it on with no load? Im not very experenced with centrifugals. Op hasn't stated how critical supply temp is.

Originally Posted by Sicofthis

Could cycle it on return temp.

Not a very good idea when there is no load. The thing will cycle itself to death as pointed out earlier.

Could cycle it on return temp.

Originally Posted by 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?

No load is no load is no load and no chiller no matter how many bells and whistles you put on it or into the programme that controls it can change that . SHUT THE FREAKIN THING OFF !!!!!!!!!!....or generate sufficient load to keep it happy .

As for how long it will run before self distruction ......... is that really relevant ???

Originally Posted by Nuclrchiller

Coming across a poor application, that has frustrated the customer and given the manufacturer a bad reputation (in the customer's eye), is an opportunity for a tech to really shine. They are not to be squandered....

Hear, hear.....

Coming across a poor application, that has frustrated the customer and given the manufacturer a bad reputation (in the customer's eye), is an opportunity for a tech to really shine. They are not to be squandered....

Originally Posted by 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.

I agree. Sounds like deja vu. But I don't think it'll get much deeper. The customer didn't need a chiller of the size they have, and they need to turn the one off that they bought. Thousand different ways to do that, but instead of turning it off the chillers a piece of crap because the compressor engineer at York doesn't agree with the guy that's been hired to work on the chiller.

MFT: I'm sorry as I can be if you don't like what's being said, but I had a 50° delta T (90° to 40°), 5 pass, 600TR PACKAGE chiller one time that ran during the winters with 43° entering water from the settling ponds at the mill. Chiller logged around 28,500 starts in 6 years (2300 volt A/L start). Four motor rebuilds for busted rotor bars before the thing finally extruded the front HS bearings out of it. Rebuilt the two sitting in the same plant on the same process for the same reasons, first one was replaced because of the halogen fire when the impeller drug on the diffuser. It wasn't the chillers fault...

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.

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?

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.

Originally Posted by 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.

Originally Posted by 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.

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.