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Member Post posted an update
York YK Low Load Issues
Hey guys, looking for some insight from the York specialists in here on a 2012 vintage YK chiller. Got a couple of things I’m tweaking on it and wanted to see what your experiences have been.
1. Lowering Condenser Water Temp (VFD Control): I’m recommending replacement of a VFD on the tower fan to control head pressure. I’m looking to see how low I can safely push the entering condenser water temperature on this vintage. Can I set the VFD to maintain a steady 60°F or 65°F ECWT, or is that pushing it too low for optimal oil return and lift? What’s the sweet spot you guys see on these YKs for maximum efficiency without causing other headaches?
2. Low Load Stall Alerts: Under light loads, I’m getting frequent stall alerts. The refrigerant charge looks solid, I’ve got a fairly steady 50% level in the sight glasses on both the evaporator and the condenser, so I don’t think it’s a charge issue. It really just seems like a low-load dynamics problem. For those who deal with these often, what’s your go-to move to mitigate this? Should I be leaning heavily on the Hot Gas Bypass (HGBP) here, or is there a better way to stage it or tweak the controls to keep it happy when the building isn’t calling for much?
Appreciate any tips or parameters you guys usually target on these units. Thanks!
Member Post, Member Post and 3 others28 Comments-
Does this YK have a VFD on it?
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@brian-medley Hi Brian,
Thanks for responding. Yes it does have a VFD.
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Hi Micheal,
Low load stall/surge is pretty common on these machines and its a result of running the condensers too cold/losing lift. We maintain a few data centers where we have 16c leaving water on the evaporator and 20c on the condenser, these machines are just choofing away like a train(surging). the customer has told us that they are very proud with their energy efficient solution of running all their cooling towers at 100% and leaving the last bit for the chillers. this leaves about 300kw for a 3.5mw machine… you get the picture.There is a software update for these machines and around version 17 we got a head pressure control output as a 0-10v from the main board. this can then be sent to a three way valve, a VSD condenser pump or in your case you could send this to the cooling tower fan. looking for around 150kpa lift.
of course hot gas is another solution but if this isn’t already installed on your variant of the machine its likely cheaper to set up the head pressure controls.
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@Vas Are the machines Yorks? YK’s
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at your data centers?
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@brian-medley yes, mostly YK’s
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@Vas Thank you for your feedback Wessal. This unit does have Hot Gas Bypass. What should the setting be for to utilize it properly?
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Mike when you are in low load conditions, What temperature tower water are you seeing entering the condenser? also what was the delta T on the evap at the time of the stall? What HZ was the VFD on the chiller and the vane position if you have it. I believe that YK vintage touted being able to do 55 degree entering tower water min as long as the leaving chw was 15 or more delta (40 degree for lift). Would be aBLE TO GET CLOSER IF YOU HAVE THE m/n AND STYLE, I have had several chillers in the YK family style I believe e-J with a 60 -65 degree entering CW and had the evaps as low as 1-2 degrees delta T and chiller right around 30-35 HZ. Now not all jobs are the same and the water loop was not that long, If you can give a few more readings I would like to analyze with you. now I have seen the HGP open only when a surge was ocurring and we wanted to protect the compressor back then but not for low load.
These are the ones I like lets dig in if you have more info. Good stuff Thanks for sharing1 -
Hi Brian,
The Tower Water temperature is at the mercy of the outdoor temperature as there is nothing controlling the Tower Fan. As for the load, last visit I had EWT of 45.8 F and a LWT of 44.7 F on Evaporator side. The Condenser had EWT of 55.2 F and a LWT of 55.8 F-
@roma01968 wow, yeah, for this temp range the entering condenser should be 60-65 in my opinion minimum for lift more to the higher.. do you recall hz and Vane position? was it WOV wide open vane at this point.
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I’ve attached a screenshot from the YK Optiview training that JCI offers. I was told that formula should be used to determine what your minimum entering condenser water temperature is. Any lower and you may start running into oil return issues.
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@loganbaum nice thanks
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@loganbaum Thank you Logan. Thats helpful
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@roma01968 no problem, glad to be of some assistance
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Logan would you be able to share the PPT by chance?
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@brian-medley I attempted to upload all of the training files that were supplied with the course. IOMs, maintenance manuals, and PowerPoint. But the zip file is too large to be attached in the comments.
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@brian-medley I am also not a paid member so I am unable to upload or view resources in the files portion of the site.
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@loganbaum oh ok gotcha i am mainly interested in the PPT I have all of the others I believe Can you forward me and I can upload for you. briandmedley@gmail .com also do you have the optispeed training workbook ? I can send that to you as well. We need to get you in the paid membership when you can we have a lot of stuff to take advantage of as well as a working AI in Chat gpt that is linked.
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I am an old school York Master tech form the early 2000’s then I went into office and later changed jobs for opportunity now doing data center chiller work and sells so I wam interested in what JCI York is saying in the latest trainings in regard ti their machines. Thanks
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@brian-medley yessir I can definitely do that. I dont believe I have any of the other workbooks, so I’d greatly appreciate that. Im a chiller technician but ive only been in the trade for 7 years so im still trying to soak up as much knowledge as I can. I hope to learn a lot from you fellas.
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@loganbaum awesome!!! when you have a chance if you can send the PPT I will send some stuff I have from my chiller class that may be helpful to you I teach 5th Year chiller class for Local 602 steamfitters in Washington DC.
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I have some classes YMC2 and others that may help out as well I may have downloaded here if not I will today and can send to you
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@brian-medley it appears I am currently unable to send you a PM. I’ve sent you a request. It also fails to upload in the comments for some reason. If you accept the request I may be able to message you then? Or if you’d prefer, attach your email and I’ll send that ppt to you.
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@loganbaum LETS TRY THE EMAIL [email protected] AND i WILL SEND YOU BACK
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@brian-medley sent
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@loganbaum sent you some content back to your email if you have any issues let me know Thanks again
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@brian-medley thank you sir!
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