chiller quessie

Discussion in 'General Discussions and Advice' started by dropzone newbee, 7 Feb 2011.

  1. dropzone newbee

    dropzone newbee

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    so ! i bought a monster 2 hp chiller
    its been installed outside about 5 meteres from tank !
    20mm piping has been used with unfortunately 3 elbow joints
    problem i have is the chiller not really cooling water properly
    chiller set to 25 degrees , but water in dsp is 27 ish

    could this be that the water warms up within its travel of 5 meteres ? ( hard to believe )

    do i need to run a larger pump from sump to chiller so that chiller gets more water in it ?

    advice please

    thanks
     
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  3. mariusmeyer

    mariusmeyer

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    Easiest way is to test the water as close to the chiller as possible, and then the water when it gets out at the end and compare. This will determine if it heats up on its way back to the tank. I dont see this happening as it should not take that long before reaching the tank. If it is the pipe then you will need to insulate it of course.

    Could the thermometer in the display be in accurate? Does the chiller work the whole time or does it switch in and off?
     
  4. mariusmeyer

    mariusmeyer

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    Also I dont know that you want a big pump feeding the chiller. It makes more sense that the longer the water has contact with the chiller, the better it will cool. No point in rushing so much water through it that it does not get enough contact time to cool down.
     
  5. dropzone newbee

    dropzone newbee Thread Starter

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    yeah- we have tested the chiller and the water coming out is spot on 25 degrees
    possibly it needs insulating as u say ?

    i have a profilux and a manual thermometer wheich is reading the same in dsp, so dont think thats the prob !

    could water flow through chiller not make the difference >? perhaps i need a stronger pump ?
     
  6. dropzone newbee

    dropzone newbee Thread Starter

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    yep , point taken
    and the volume of water going into chiller ???
     
  7. dendrosa

    dendrosa Member

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    If the water coming out the chiller is at the set temp ( 25) then the chiller is doing its job. If the water in the sump is higher than 25 then more heat is being added than what the chiller is removing. So yes , you do need to go for a stronger pump / higher volume through the chiller.
     
  8. dropzone newbee

    dropzone newbee Thread Starter

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    ok, makes sense
    but wouldnt a stronger pump mean that the water is been pumped through quicker and resulting in less cooling ?
    or does the volume of water been pumped through make the difference ?
     
  9. dendrosa

    dendrosa Member

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    The amount of heat being pulled out of the water remains the same, so yes the the higher the volume of water through the chiller, the lower the temperature drop between the input and output. Ideally you should crank up the volume so that the output is above the thermostat set point but below the input temp - say about 26 in your case. This output temp will drop as the input temp drops,ideally eventually being equal to the input temp at the desired value of 25. I don't believe you can have too strong a pump feeding your chiller ( flow resistance obviosly taken into account)
     
  10. dropzone newbee

    dropzone newbee Thread Starter

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    great
    thanks for advice
    will try a stronger pump :)
     
  11. dendrosa

    dendrosa Member

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    What pump are you running at the moment?
     
  12. JD167

    JD167

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    Hey Dropzone

    How is your chiller plumbed into your system? Which chamber does the water return to? Where is the temerature probe? Inside your DT or inside the sump?

    We had some scorchers in Cape town last week and I found my chiller was running most of the day. I saw a design flaw in how my chiller was plumbed and redid the chiller return so that it flows as close to the DT return pump as possible. My temperature probe has always been in the DT.
     
  13. dropzone newbee

    dropzone newbee Thread Starter

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    i think its a 4800l/h in the sump
    2 hp , hailea chiller
    20 mm pvc piping from dsb to chiller and back
    and remember it runs about 5 metres with 3 or so elbow bends
     
  14. dropzone newbee

    dropzone newbee Thread Starter

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    howzit
    the water returns into the main sump area
    the probe is inside the sump and the glass thermometer inside the DT (temps very similar )
     
  15. dendrosa

    dendrosa Member

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    Mmm.. I wonder if you do not have a bit of a restriction problem here... that 20mm pvc piping, is that 20mm ID or 20mm OD?
    A 2hp chiller should be able to handle between 3000 - 6000 l/h through it. 4800l/h is a decent flow. Can you measure what your output volume is?
     
  16. dropzone newbee

    dropzone newbee Thread Starter

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    not sure , normal 20 mm pvc . i would imagine it is OD :whistling: im restricted as cant go more than 20mm

    must say , the amount of violume pumping into sump is pretty dramatic
    really good flow IMO
     
  17. Bob the (reef)builder

    Bob the (reef)builder

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    Don't get a new pump until you up your pipe size. Even if you have to drop it back to 20mm through the wall and increase it afterwards again.

    Although if your water flow is good then maybe its something else.

    If the water coming out is not significantly cooler on a 2 HP unit then the chiller is not chilling and needs attention.
     
  18. dropzone newbee

    dropzone newbee Thread Starter

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    anable to up the pipe size as it had to be chased into the wall ( long story that 1 ) :blush:

    yeah , rob , already checked if chiller is working and it seems fine
     
  19. dendrosa

    dendrosa Member

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    Dropzone, I think this may be your problem. If that pipe is 20mm OD you probabally only have an ID of some 15mm. At that size with a normal aquarium type pump which is able to deliver a pressure head of about 2m or so, I estimate that you would be getting 2500 to 3000 l/h through that pipe. This pump is also working hard to overcome the frictional forces in your pipework, therby adding to your heat problems.
    Can you not make a plan to plumb this pump outside your sump, thereby removing a heatsource?
    BTW untill you are sure you can get the additional volume to flow through your system I would hold back the decision to go for a bigger pump. Because of your pipe restrictions I would reccomend your aim should be to restrict your heat sources
     
  20. dropzone newbee

    dropzone newbee Thread Starter

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    makes sense
    thanks for your time
    lemme see what i can do
     
  21. dendrosa

    dendrosa Member

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    No problem dropzone, goodluck. For interest sake though, could you measure your ouput flow and post? It may provide some usefule insight
     
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