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  1. #14
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    If this is the first startup of the year, and youre just starting to make ice, then yes, you have too high of a load.

    The problem with using approach is that you dont know what the system approach is supposed to be. The only way to know for sure is to have design water flow, design refrigerant temps and pressures, design outdoor conditions, and clean tubes. Otherwise youre just guessing.

    I have a rink that when you go down and start to lose the ice, you have to choke the suction service valves back to keep the suction pressure and amp draw down. These are large open drive compressors with 100 Hp motors. As the load drops off, you can open the valves back up.

    I think your more experienced guy has been taught that its outdoor temp. And hes just repeating that, not understanding that its actually the high load while starting to make ice.

  2. #15
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    I have some; yes.

    I can't think of a reason - unless it was specifically designed for winter-time only operation? I did a few of those for residential customers.

    What kind of ice rink is this? Is it indoor or outdoor?
    Olympic sized commercial? Where they rent ice-time to professionals around the clock?

    If indoor: how is the enclosure being conditioned? And to what inside temperature and humidity?

    Why are you asking this question?

    PHM
    -------


    Quote Originally Posted by superheatmaster View Post
    Anyone have experience with chillers that freeze the water for an ice rink? Lets say a water cooled system, any reason why it shouldn't be able to run when its 60 degrees outside?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  3. #16
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    Sounds like dirty condensers and the on-site 'repair' was to set the tower water setting lower and lower. The fouling eventually overcame the ability / capacity of the tower and . . . . here you are. <g>

    I don't know that guy who is advising you - but your description has my BS Meter edging towards the DEFCON STUPID limit peg.

    PHM
    --------



    Quote Originally Posted by superheatmaster View Post
    Yes with Glycol.

    Now or the issue... I am by no means an expert on chillers, certainly not done anything with one for an ice rink...

    There is 4 compressors.. 2 condenser barrels ... (2 compressors for each condenser barrel) ... Cooling tower on roof set to 55 degrees water temp so if above, 55 it kicks the fan on...

    First startup all compressors trip.... 3 an 4 high discharge.. 1 overload .. 2 I dont even remember... The experienced guy I was with said it was too warm outside.. My first inkling was is this dude blowing smoke because its a water cooled condenser and the water temp was 57 degrees. Suction pressures looked in range according to the display controller. .. I say we check the strainer... I did.. some chit was in it, sand, etc... restart system.... compressor 1 and2 higher than they should be, but dont trip... 3 and 4 are close to tripping high discharge but do not...

    Experienced mech said again, to warm out... and ice rink chillers are different...

    I thought to myself they should still use condenser approach temp .... if 1 and 2 are much lower than 3 and 4 .. obviously there is an issue with 3 and 4 ...

    Anyways, I dont know if I provided enough info... but it just didnt make any sense the answer i was getting back from the experienced chiller mech.. They only had leaving water temp from tower, the supply to tower had a missing sensor..

    This was not a service call, was there to assist with motor replacement in tower... happen to watch what the mechanic i worked with was doing. When he tried saying it was the same thing to an ac tripping on a hot day I just gave in and said ok... I didnt want to argue.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  4. #17
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    Thread Starter
    Quote Originally Posted by 71CHOPS View Post
    If this is the first startup of the year, and you’re just starting to make ice, then yes, you have too high of a load.

    The problem with using approach is that you don’t know what the system approach is supposed to be. The only way to know for sure is to have design water flow, design refrigerant temps and pressures, design outdoor conditions, and clean tubes. Otherwise you’re just guessing.

    I have a rink that when you go down and start to lose the ice, you have to choke the suction service valves back to keep the suction pressure and amp draw down. These are large open drive compressors with 100 Hp motors. As the load drops off, you can open the valves back up.

    I think your more experienced guy has been taught that it’s outdoor temp. And he’s just repeating that, not understanding that it’s actually the high load while starting to make ice.
    Yes startup.. Agreed high load, but that does't explain the difference between comps 1/2 and 3/4 ... Something wasn't right.

    The rink is outdoors, has a main pipe that has hundreds of these plastic looking hoses that run into the rink.

    So you think it was just high load? Those hoses were exposed to outdoor air.. no water was running on top of them.

    Shouldn't the condenser water be set higher than 55 degrees? Shouldn't the approach be more or less in the same ball park as any other water cooled condenser? give or take?

  5. #18
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    Thread Starter
    Quote Originally Posted by Poodle Head Mikey View Post
    I have some; yes.

    I can't think of a reason - unless it was specifically designed for winter-time only operation? I did a few of those for residential customers.

    What kind of ice rink is this? Is it indoor or outdoor?
    Olympic sized commercial? Where they rent ice-time to professionals around the clock?

    If indoor: how is the enclosure being conditioned? And to what inside temperature and humidity?

    Why are you asking this question?

    PHM
    -------
    Outdoor rink in a park, used in winter only.. size I would say same as a hockey rink.

  6. #19
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    Quote Originally Posted by superheatmaster View Post

    Those hoses were exposed to outdoor air.. no water was running on top of them.

    A chiller with no water has no load.
    In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".

  7. #20
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    .
    In honor of RichardL: "Ain't 'None' of us as smart as 'All' of us".

  8. #21
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    ok, so you said 407C ....lets ASSume it's designed for a 90* condensing temp, and 15* evap temp. (just for argument). that puts you at around 170 psi head and around 45 psi suction.

    so you had a 55* ambient, which meant the glycol was also 55*.....if you convert that to psi it's 88. granted it's not a direct correlation between the two, but you see where I'm going. you're trying to pull 55* down to 15*......that's a wide swing. condensers are only designed to reject so much heat, and that's all they will do. so on a hot pull down, you're going to see higher than normal pressures across the board.

    so you said you had 200psi on 1/2. that's 101* saturated......a little high, but not too bad really. 3/4 you said 300 psi, that's 128*....that's getting way too high.

    now, you said they both started and ran the second try......one thing to keep in mind about chillers, is that refrigerant can move around in the systems during long off times. It may take several tries to get everything back to normal levels. especially process machines. Is the evap. DX or flooded?

    ok, so now you're running. approach was not even close between the 2 condensers. what was the approach on 1/2 and what was it on 3/4. are there separate pumps for each condenser? separate fans in the tower, or do both circuits share a single tower and fan? are there triple duty valves? you said you cleaned the strainer......was that the pump suction strainer, and was which condensers?

    have you done any research regarding what kind of maintenance gets done to the system? is there a pre start PM? oil, filters, tube brushing, strainer and tower cleaning, belts, etc. etc.?

    While I do agree that 3/4 pressures are high, there are more things that need investigated before pulling heads. It also sounds like your more experienced tech doesn't truly understand the system. while it is a technically a process chiller, it's still just a chiller.....but it would fall into the low to medium temperature range. that changes things a little when it comes to design. when you run a chiller (any chiller) outside of design conditions, you can get all kinds of funny things happening.

    as far as the tower water set point, 55* is only 88 psig......which is way off from your design saturated temp of 90* and 170 psi. if this is a DX system, that can cause other problems. I'm leaning toward the statement someone else said that the water temp has been dropped as the tubes fouled (or something else has been happening) to keep the unit on line. by driving the temp down, you're gaining condenser capacity.

    from everything you're saying, it sounds like this system is a mess, and your company should seek the help of someone who has more experience with these systems. Not trying to be rude, at all, just stating the obvious. If I were you I would tread lightly....when you start pointing out how wrong something is, people (companies and customers) tend to get upset.

    what generally happens with these seasonal systems is that there usually isn't anyone that specializes in chillers in that area. so you end up with a company that has little experience, and over time, problems add up and add up, until you start getting multiple failures. I know of one seasonal rink that eats a compressor every year......the owner has been convinced that it's normal. the unfortunate part is that tax dollars pay for the upkeep, and there is no way to convince them to change anything. I'm not at all trying to discourage you, quite the opposite, in fact this may be a prime opportunity for you. you may be able to convince your company to let you start doing some work on the equipment.....if you could it would be a fun project for us all!

  9. #22
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    could also be seriously undersized towers?
    Keep it simple to keep it cool!

  10. #23
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    but I agree with al above dirty condenser tubes and high pull down
    Keep it simple to keep it cool!

  11. #24
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    If there is no rink floor water to freeze - there is no heat load to speak of for the chiller. Water is in the neighborhood of 1000 times more dense than air. So the tubes have virtually no surface area in comparison to an air coil with fins. If the compressors ran for more than a few minutes all the water would be chilled and returning at almost the same as leaving. Both the suction pressure and the discharge pressure should be trending low.

    Typical system condenser design would want the discharge pressure in the 100-105 range. Which would typically require condenser water in the 80-85 range.

    Of course anything is possible so the winter-only design could have used 'under-sized' condensers and 55 water - but that is skirting somewhere close to thermal-shock territory - and specialty-designs cost money - so I would initially take the position that it's all just a bunch of off-the-shelf equipment. So I'd be expecting a 2-3 approach.

    PHM
    --------




    Quote Originally Posted by superheatmaster View Post
    Yes startup.. Agreed high load, but that does't explain the difference between comps 1/2 and 3/4 ... Something wasn't right.

    The rink is outdoors, has a main pipe that has hundreds of these plastic looking hoses that run into the rink.

    So you think it was just high load? Those hoses were exposed to outdoor air.. no water was running on top of them.

    Shouldn't the condenser water be set higher than 55 degrees? Shouldn't the approach be more or less in the same ball park as any other water cooled condenser? give or take?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  12. #25
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    you need to slow the leaving water down on the evaporator, as the water starts cool down gradually open up. Did a start up in Mexico years ago at nuclear power plant, load was extremely high finally go it to working!!!!

  13. #26
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    Quote Originally Posted by superheatmaster View Post
    ...compressor 1 and2 higher than they should be, but dont trip... 3 and 4 are close to tripping high discharge but do not...
    are the condensers in series with each other? if so, does the condenser for 1 and 2 get the coldest water?
    "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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