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  1. #14
    Join Date
    Jul 2013
    Location
    Atlanta, GA
    Posts
    17
    Quote Originally Posted by KnewYork View Post
    This chiller should be able to run at less than 60 Hz. with 76° ECW. I don't know where this chiller is located, but 65° condenser water cannot be achieved in many areas of the country in the summer even at night. The clue here is that when he manually slows the VSD an the PRV begin to open and it probably is running fine. As soon as he releases it it goes back to 60 Hz. Far more indicative of a corrupted surge map than condenser water that is too warm.
    Quote Originally Posted by tacxc View Post
    It make difference if there's no load. The gas cfm through the diffuser helps the gas from flowing backwards, so load is relevant to lift. Yorks don't operate well with light loads unless you lower the lift. Yorks have vaneless diffusers and a wider stall window than any other machine. I had same issue during winter time as was able lower condenser water, chiller purred like a kitten afterwards. In the case of your chiller has no load in summer time is another issue. Are they running 2 chillers together or is it that that machine is really that over sized? There definately alot of stuff you need to look at as others are mentioning here verifying flow and dumping surge map. In my case I dumped the map and after about a week I was back to square one. My chiller was running at 56 - 57 htz. Also vanes closed. After dumping map ran at 35htz with vanes closed. By setting my set point to 65 degrees I've been able to match the load to the right entering condenser water temp even though the tower is always able maintain that setpoint. The theory is, when osa conditions go up so does the building load. There is an article that explains these condition in more depth.
    The pumps on both sides are constant volume. Single machine. The tower water is set at 71° so the tower just runs 60Hz all summer. I run the building from 7am - 6 pm M-F so the chiller doesn't run after hours save, optimum start.

  2. #15
    look at surge count if it is excessivly high i would try clearing the surge map also york yk's and yt's with vsd they recommend conndenser water in the 50's depending on time of year and location that may be hard to achieve but i would try to get water colder but never lower than mid 50's

  3. #16
    Join Date
    Jan 2011
    Posts
    1,114
    Quote Originally Posted by DFWTECH View Post
    look at surge count if it is excessivly high i would try clearing the surge map also york yk's and yt's with vsd they recommend conndenser water in the 50's depending on time of year and location that may be hard to achieve but i would try to get water colder but never lower than mid 50's
    I used to have the lower the better mantra, but it gets to a point where the law of diminishing returns causes more money to be spent that can be saved. Remember the savings provided by a VSD is geometric not linear. The bulk of the savings is achieved at about 40 Hz. Yes, there is savings below that point, but one has to determine if the extra HP being consumed to run all the tower fans at 60 Hz. can be "made up" by the chiller running a little slower.

    With many years and all the different VSDs York used I came to realize that 60-65*F. water to the condenser was more than sufficient.

    This man's problem is not tower water temperature. There's more going on here.

  4. #17
    Join Date
    Jul 2013
    Location
    Atlanta, GA
    Posts
    17
    Yeah, I'm simply not going to make tower water in the 60s anytime at this point in the year. It's too hot outside.

  5. #18
    Join Date
    Jan 2011
    Posts
    1,114
    Quote Originally Posted by rjcuomo1 View Post
    Yeah, I'm simply not going to make tower water in the 60s anytime at this point in the year. It's too hot outside.
    How many ACC surges are there on this machine?

  6. #19
    Join Date
    Jul 2013
    Location
    Atlanta, GA
    Posts
    17
    Total surge count is at 827 over the life of the machine which is 12 years old.

  7. #20
    Join Date
    Jan 2011
    Posts
    1,114
    Quote Originally Posted by rjcuomo1 View Post
    Total surge count is at 827 over the life of the machine which is 12 years old.
    That doesn't sound too bad, but sometimes it doesn't take much to corrupt a map. The problem with the older machines is that there may only be a few points that are messing up the whole operation, but to get rid of them the entire map has to be cleared. The newer machines (last 5 years or so) allow for individual points to be cleared.

    If I were able to stand in front of the machine and manually control the speed and have it remain in control without surging, yet when put back in auto it would ramp back up, I may be inclined to clear the surge map.

    Another question or two...

    How many hours and starts?

    Are there excessive shutdowns on leaving chilled water temperature?

  8. #21
    Join Date
    Jul 2013
    Location
    Atlanta, GA
    Posts
    17
    Run time is 15353 hours, starts are 16321.

    I've been working on getting the starts down. When I inherited this machine last year, it had 15009 starts. I've been dealing and solving several problems with it over the course of the year that been causing it. I had a bad DP switch. Controls settings set wrong. Chiller/controls interface set wrong. Light loading because of lack of occupancy in my building & time of year. Optimum start/stop issues. These problems have been linked to the leaving chilled water shutdown and the excessive start/stops. All of these have been solved except the optimum start/stop. I have my controls guy working on reprogramming that because for some reason, it's starting the chiller way earlier than the AHUs to anticipate AHU start up. But it take only a few minutes for that chiller to take the CHW loop down to set point with no load on it. So it cruises past set point and trips on leaving chilled water temp.

  9. #22
    Join Date
    Jul 2013
    Location
    Atlanta, GA
    Posts
    17
    Well, I get all the problems worked out with the buildings optimum start and go to clear the surge map and low and behold, it has it's own special password. I can't find manual 160.55 M1 which has it. ggggrrrrrrr!!!!

  10. #23
    Join Date
    Jul 2013
    Location
    Atlanta, GA
    Posts
    17
    Got York to take a look at it. They reset the surge map and now it's running down in the low 50s Hz. Thank you all for your help, I really appreciate it!

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