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  1. #27
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    Aug 2009
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    Prattville, Alabama
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    Duplicate post. sorry, got lost, lol.
    In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".

  2. #28
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    Quote Originally Posted by Hard Restart View Post
    I think that is exactly the problem. The only way to manipulate the heat removal in the free cooling loop would be to modulate the fans. That would ensure there is enough load on the mechanical cooling to meet miminimum compressor capacity and not trip on low discharge pressure. Except the EWT at the barrel is what tells the mechanical cooling how much work needs to be done. By the time the water gets there, the fans are done doing their job. Like having teeth in your butt, by the time it gets there, the work is already done. The fans would almost have to predict the EWT at the barrel, BEFORE the water enters the free cooling loop.
    From a mechanical cooling perspective, the only difference I see between this chiller and a conventional one is it's ability to (in effect) reduce the load on the chiller (mechanical cooling). Sounds like issue is, due to the "load reduction" being located onboard the chiller itself, that change in load is seen as rapid, and maybe even large. Is there any way to slow down the control response of the free cooling? I would slow that down as much as it will allow. I wouldn't care if if it's ridiculously slow.
    In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".

  3. #29
    Join Date
    Nov 2019
    Location
    Dc
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    3
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    I’ve seen a lot of problems with free cooling applications due to reduced flow rate through the free cooling coils. Engineers need to be thoughtful of a much higher pressure drop. I haven’t seen a York but I’ve seen boat loads of Trane’s with the free cooling.

  4. #30
    Join Date
    Feb 2019
    Location
    Northeast Ohio
    Posts
    21
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    We're really struggling with ours. We've got three of them, but to add insult to injury, two were converted to hybrids by the addition of free cooling coils after they left the factory, by another company that does this. Apparently York sold a kit for a while. But beware: if you do this, the fans now aren't capable of moving enough air through the hybrid coil package due to the added pressure drop. SO that's nice.

    Our one chiller that came as a hybrid from York (purchased last year) has had ongoing problems with high discharge pressure. Like all of these chillers, a single fan VFD runs to a terminal strip and feeds multiple fan motors. I believe ours have only 3 VFD's feeding TWENTY fans. So when one fan draws too much current (and these motors seem to have about a 6 month lifespan), it takes out the entire VFD that's feeding it, dropping the fan capacity to such a large percentage, the entire chiller shuts down on high discharge. So yes, you heard that right...a SINGLE fan failure can take out an entire 20-fan chiller. It's happened to us repeatedly.

    One of our original converted hybrids has recently developed a weird symptom...for no apparent reason, all 20 fans will come on at 100% with no call for cooling and no flow through the unit. JCI has been out twice; they have no idea why. There's a section in the manual that talks about this happening if the VSD cabinet reaches 153F internally, but with ambients in the 30's in Cleveland, that's certainly not the case. We were told it might be a sensor (there are three of them in that cabinet) and that we should check those sensor outputs next time it happens (you can see their data from the front panel controller). Well, we did, and the temps were perfectly normal.

    I've worked at this company for 3 weeks now, and we've had JCI onsite 4 times, and another contractor twice, attempting to get these things even remotely reliable. At this point, I'm ready to push them off my roof.

  5. #31
    Join Date
    Mar 2005
    Posts
    1,300
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    here in the UK theres Airedale and 2 or 3 of the Italian chiller manufacturers selling these such as Aermec all with pretty good results,
    I worked with floating head pressure projects for quite some time so there is a trade off in compressor power to fan power that must be watched carefully same with thicker doubled up coils such as these. I would have thought York would be up on their game with this

    https://www.youtube.com/watch?v=5R4GqsI-S2A
    Keep it simple to keep it cool!

  6. #32
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    6,893
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    Quote Originally Posted by OHDataCenterGuy View Post
    We're really struggling with ours. We've got three of them, but to add insult to injury, two were converted to hybrids by the addition of free cooling coils after they left the factory, by another company that does this. Apparently York sold a kit for a while. But beware: if you do this, the fans now aren't capable of moving enough air through the hybrid coil package due to the added pressure drop. SO that's nice.

    Our one chiller that came as a hybrid from York (purchased last year) has had ongoing problems with high discharge pressure. Like all of these chillers, a single fan VFD runs to a terminal strip and feeds multiple fan motors. I believe ours have only 3 VFD's feeding TWENTY fans. So when one fan draws too much current (and these motors seem to have about a 6 month lifespan), it takes out the entire VFD that's feeding it, dropping the fan capacity to such a large percentage, the entire chiller shuts down on high discharge. So yes, you heard that right...a SINGLE fan failure can take out an entire 20-fan chiller. It's happened to us repeatedly.

    One of our original converted hybrids has recently developed a weird symptom...for no apparent reason, all 20 fans will come on at 100% with no call for cooling and no flow through the unit. JCI has been out twice; they have no idea why. There's a section in the manual that talks about this happening if the VSD cabinet reaches 153F internally, but with ambients in the 30's in Cleveland, that's certainly not the case. We were told it might be a sensor (there are three of them in that cabinet) and that we should check those sensor outputs next time it happens (you can see their data from the front panel controller). Well, we did, and the temps were perfectly normal.

    I've worked at this company for 3 weeks now, and we've had JCI onsite 4 times, and another contractor twice, attempting to get these things even remotely reliable. At this point, I'm ready to push them off my roof.
    I will come out...but the travel charges might be a bit much. Yes, some of the fan motors do fail but I am not aware of a major issue. The motors I have seen fail, you could hear them failing for about a month before they gave up the ghost. I would recommend replacing the temp
    sensor...they aren’t that expensive especially considering the cost of techs coming out. There is a fan VFD software upgrade that came out this Summer/early Fall (I think) that was supposed to fix some issues. The upgrade is for the drives, not the JCI software and it takes a while to install it.
    "Right" is not the same as "Wise".

    Don't step on my favorite part of the Constitution just to point out your favorite part.

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