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Thread: York YTJ Chiller Controls Questions & Tower Specific Questions

  1. #1
    Join Date
    Apr 2006
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    York YTJ Chiller Controls Questions & Tower Specific Questions

    I am in the process of preparing for a DDC controls upgrade on an existing chilled water plant that has (2) York YTJ centrifugal chillers. This customer has had a lot of DDC controls related issues with their current system that I don't want to repeat. I have a few questions in regards to our existing setup and overall YTJ chiller controls capabilities:

    Can some sort of BACnet card get added to these chillers for additional monitoring? Or are the controls too old? I have included some pictures of the existing controls. If there isn't BACnet capabilities, how about Modbus capabilities? These YTJ chillers were installed back in 2002-2003.

    I see that remote analog signals can be tied to these chillers. Right now, it appears that the existing system is just allowing the customer to reset the chilled water temperature setpoint within a specific range. Does this chiller controller have any other points that I could send a signal to that would be worth my time? I don't really want to get into controlling the chiller. I just want to enable it, monitor it, and send it a setpoint.

    New cooling towers just got installed on this building. The three towers are connected together as if they are one cooling tower. There is no automatic isolation valves installed. All three towers together are designed for a total of 3600 GPM. However, each chiller/ condenser water pump is designed for 1800 GPM (there are two chillers/ pumps). Typically, I am used to having automatic isolation valves to where I can shut down one cell when I am only running one chiller. Right now, when one chiller is running they are running 1800 GPM of water and spreading it across all three cells (designed for 3600 GPM). I assume there are some draw backs to doing it the way they are doing it? I am sure the flow rate across the cooling tower fill is too low. Does this affect the overall efficiency of the cooling towers? Does this affect the rate of evaporation? I would like to fully understand the benefits of having isolation valves on the cooling towers, so I can make the proper recommendations to the customer. I assume I would need automatic isolation valves on the entering and leaving sides of each cooling tower?

    Right now, the existing system is trying to maintain a constant 72 degree condenser water supply temperature (into the chillers). I have heard that York YTJ chillers like cooler condenser water. Is there any issue looking at doing condenser water reset based on the outside wet bulb temperature? I feel like the tower fans just run at 100% all of the time trying to get down to 72 degrees (which will never be possible on certain days).

    Ever since I have worked at this building, I have heard the chillers surging. The chiller technician mentioned low load. Is there anything that I can do from a controls perspective to help eliminate the surging situation?

    Your feedback is appreciated!

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    J. King

  2. #2
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    Talk to York about controlling tower water flow using condensing head pressure that results in maximum efficiency. This should show the energy that can be saved and lead to possible changes in the existing system.
    No man can be both ignorant and free.
    Thomas Jefferson

  3. #3
    Join Date
    Apr 2020
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    va
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    Like WAYNE aid, tower should be controlled by the chiller based on lift or pressure ratio. Tower bypass is recommended for mild or cool weather to prevent inversion. No point running with a tower fan setting below wet bulb.
    Chiller control manual should list available io.

  4. #4
    Join Date
    Dec 2014
    Location
    New Mexico
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    On a York with a VSD drive the cooler tower water the better. If this chiller has the oil cooler up on top of the condenser heat exchanger , near the oil sump, 61-62 F is about as cool as you want to go. Cooler tower water does not provide enough lift to push liquid ref. up to the oil cooler. If the oil cooler is down in the evaporator you can shoot for 55 F.
    If there is surging , could be the surge map need to be cleared and the cause of the surge map being full corrected. Air in the chiller and water flow are the most common causes of the surge map to fill up limiting performance.
    That Opti-View panel will accept temperature reset and current limit input of 0-19 VDC or 4-20 milliamperes, pulse width as well.
    York has a inter face card that will allow you to do set point change , stop/start and give you full information of chiller operation.
    Running the towers with to little flow to the media could cause the mineral deposits to build on the entering edge of the media. If each cell will take 1800 GPM and you have 3600 GPM total just run two cells, may have to balance the basins


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  6. #5
    Join Date
    Aug 2019
    Location
    LA
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    The York SE card will give u full data in back net how ever I don’t think the SE cards work with 1730 boards. Best practice is to operate chillers at design water temps and flows for best results.

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