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Thread: YLAA PHE

  1. #1
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    YLAA PHE

    Hi all.

    Has anyone flushed out a PHE on a YLAA chiller (R410A) ?

    Just wondering what solution you would have used if so?

  2. #2
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    No but I would say it's similar to backflushing any phe.

    You need to backflush with the same flow.
    So can you with flexible pipe reverse water in and water out. Keep filtering your inlet.

    Depending on what you think is there you can circulate some cleaning agent like Rydlyme in it

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  4. #3
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    Back flushing on this one will not be so easy.
    This Chiller has its now hydrokit
    But should be able to manage it. I just need some down time, and the only time this customer stops production is a 12:30 am to 08:30 am

    Customer drained the 7000 litre tank yesterday to see if there are any issues with it. He says it spotless.

    symptoms:

    Getting massive approach temps Around
    Return temp from process is 16 - 18 DegC to chiller
    Verified that this is actual
    Chiller leaving water temp is 6.5 DegC
    Actual leaving water temp is 14 DegC

    At 7.3 bar on R410A, approach is somewhere around 15 DegC
    Both system are the same, so my back pressure is low for the RWT temp

    So chiller will not load any further. It thinks it doesn't need to.
    Sensor is fine, if I turn off the chiller and let it sit for a bit, chiller LWT will be the same as actual LWT.
    I changed sensors anyway for a new one, no difference, Swapped the RWT sensor to the LWT sensor, no difference.

    My flow rate is down a bit, should be 11 L/sec, sitting at 8 or so.

    So I am likely looking at a fouled up PHE

    I should say that I changed the TXV on system 1 this week. Whilst working on it, I noticed at one point that the chiller LWT & RWT were extremely high.
    Higher than usual for this site.

  5. #4
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    Glycol?

  6. #5
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    Thread Starter
    12.5% PG

  7. #6
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    Was there a minimum concentration of 20-25% to prevent bacteria growth.
    Might only be here

  8. #7
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    The glycol is going to add a bit of approach but not too much. Did you include the extra pressure drop in your calculations determining GPM? While it is easy to say the PHE is the culprit (it is the common point between both systems, don’t discount other issues that just happen to be relatively close to each other. What is your discharge superheat and/or suction superheat?

  9. #8
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    They have inhibitor in the water/glycol to prevent bacteria growth anyway, so that should be fine.
    They drained the 7000 Litre tank at the weekend and let it back flush through the PHE. No dirt/grit cam out tank the tank is clean.

    loading up each circuit indivadually (2 comps per system) suction superheat is between 7 - 8 DegC
    Sub-cooling sitting around 9 DegC
    Discharge superheat Is about 6 DegC

    Where the LWT sensor is on these chillers is probably not the best IMO, I'd like it in the actual leaving chilled water pipe.

    Anyway, I will be back to site next week. According to my ultra-sonic flow meter, I am getting about 8 L/sec, BUT when I use the square Law to determine the flow, its telling me I am up around 17 L/sec.
    Damn thing is driving me nuts..

  10. #9
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    Glycol mfg recommends min of 25-30%. Any less requires additional water treatments or you will have corrosion/fouling issues.

  11. #10
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    Quote Originally Posted by Chillmac View Post
    …loading up each circuit indivadually (2 comps per system) suction superheat is between 7 - 8 DegC
    Sub-cooling sitting around 9 DegC
    Discharge superheat Is about 6 DegC

    Where the LWT sensor is on these chillers is probably not the best IMO, I'd like it in the actual leaving chilled water pipe.

    Anyway, I will be back to site next week. According to my ultra-sonic flow meter, I am getting about 8 L/sec, BUT when I use the square Law to determine the flow, its telling me I am up around 17 L/sec.
    Damn thing is driving me nuts..
    6C discharge superheat is way too low for a scroll compressor…that is basically floodback…or very close to it. If you are flooding back then you aren’t having heat transfer. I would trust the flow meter. A pressure drop measurement only works on the PHE if the passages are as clean as they were when it left the factory.

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  13. #11
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    what model number is it? what is the design data (if you have 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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    How is the dsh sh lower than the ssh? Does it have li or oil cooler?

  15. #13
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    Suction superheat is much more difficult to measure than discharge superheat. I will sometimes record suction superheat, but I don’t pay much attention to it.

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    Quote Originally Posted by jayguy View Post
    Suction superheat is much more difficult to measure than discharge superheat. I will sometimes record suction superheat, but I don’t pay much attention to it.
    Dx brazed plate evap, no problem checking ssh. Definitely needed for analysis.

    You may be referring to flooded evap where ssh may be 1-3*f.

  17. #15
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    c&d tool core remover tool with in stream thermometer in these instances all the way
    Keep it simple to keep it cool!

  18. #16
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    Quote Originally Posted by ehsx View Post
    Dx brazed plate evap, no problem checking ssh. Definitely needed for analysis.

    You may be referring to flooded evap where ssh may be 1-3*f.
    Suction superheat is difficult to get accurately due to thicker copper, colder temperatures make for thicker oil and condensation. Especially if you have to peel the insulation to add a probe. I am not saying it is impossible. I am saying that it is difficult.

    Now, discharge superheat is easier since the copper is thinner, warmer temperatures make the oil thinner, it is much higher than the ambient temperature and no condensate to deal with (usually). If you are a few degrees off (+ or -) on the discharge superheat…not a big deal. But the suction superheat is already a lower value so a few degrees makes a bigger difference.

    It is still a good number to get but I do t put as much stock in the value since it is difficult to get accurately.

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  21. #18
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    Quote Originally Posted by jayguy View Post
    Suction superheat is difficult to get accurately due to thicker copper, colder temperatures make for thicker oil and condensation. Especially if you have to peel the insulation to add a probe. I am not saying it is impossible. I am saying that it is difficult.

    Now, discharge superheat is easier since the copper is thinner, warmer temperatures make the oil thinner, it is much higher than the ambient temperature and no condensate to deal with (usually). If you are a few degrees off (+ or -) on the discharge superheat…not a big deal. But the suction superheat is already a lower value so a few degrees makes a bigger difference.

    It is still a good number to get but I do t put as much stock in the value since it is difficult to get accurately.
    Never seen thicker cu on suction, don’t take reading on bottom of line due to oil, if readings are low I will use 2-3 probes on suction to check for carry over. Probes secured & insulated.

    Comparing ssh, dsch sh, suction pressure, & evap approach allows confirmation of excess oil, txv operation, compressor condition, injection control, etc.

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  23. #19
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    i wasn't clear...the suction line copper is typically going to be thicker than the discharge line copper.
    "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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