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 KnewYork
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.
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.
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
Originally Posted by man from trane
This entire discussion is explained in great detail in IOM 160.54-m1 this thread should be in the pro forum.
Arguing with your Boss is like wrestling with a pig in
After a while you realize that while you are getting
dirty, the pig is actually enjoying it.
It is not exactly cheating, I prefer to consider it
creative problem solving.
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Originally Posted by klove
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That might not be out of the question!