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Thread: Chiller thermostat?

  1. #1
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    Chiller thermostat?

    What I need is protection against condensation.

    Looking for a thermostat that reads local ambient then sets itself to a degree or two above (programmable) to control chiller to always run at lowest temp possible for any given ambient.

    Am I describing a product you know about or do I have to build it?


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  2. #2
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    Well, you need to know how humid the environment is as well. This can be determined with a dry bulb and wet bulb temperature.

    If you don't have that type of thermometer you can make your own with a little make shift get up.

    First, using an air thermometer, get a reading of the air temp and record it. Then wet a paper towel and wrap a small swab around the bulb and shake it through the air and keep taking readings until the temperature has stabilized. Record that temp.

    The relationship between the wet and dry bulb temperature will give you a relative humidity. Look for a Psychometric chart. Google it.

    The bottom line represents dry bulb. Locate your D.B. Temp. The upper line (curved) represents your W.B. temp. Find your temp.

    Follow the line straight up from your dry bulb and the wet bulb diagonal line parallel to the ones on the chart until your vertical and diagonal line intersect. Then determine which humidity envelope you are in. This is shown by the curved lines that follow your wet bulb temperature and usually are marked with the percentages.

    For example, if your D.B. temp is 70 degrees and your W.B. temp is 55, then you have relative humidity of a little greater than 30%. The closer your wet and dry bulb temps, the higher the humidity. If they are equal, then that is 100% humidity (Very unlikely).

    At that point you can determine your dew point.

    Use this. http://ag.arizona.edu/azmet/dewpoint.html

    That temperature is where condensation will develop. It is your best bet to use that to determine then what type of setting you want. There are electronics that can do all of this for you, but they are expensive and impractical for your application.

    Insulation is your best bet to protect from condensation unless you plan on tediously changing water temps. I would take readings of the above temps and use the chart and formulas to determine your normal humidity levels and ambient temperatures and then set your chiller for the designated temperatures.

    You don't need to really have thick insulation either for the temps you want. Also, knowing the ambient temp and relative humidity is very important for determining the thickness of insulation that you will need. Its far better than trying to figure out what temps to set your chiller for and having to worry about when to change it. It just doesn't make sense.
    Regards, Stew.....

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  3. #3
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    Secondly, process I described is by no means exacting; there are other factors that will determine when condensation will appear.

    Wouldn't want you to get into trouble.
    Regards, Stew.....

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    Thanks Stewie, you make it sound so simple now

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    Its much easier to show people than for me to explain it..... hehehe.....

    However, given what he wants to do the advisement I gave is accurate; if a bit cumbersome :p

    Additionally..... the more ridiculous I make it sound the more likely he is to protect his electronics with insulation rather than a wee guess at the dew point...
    Last edited by Stewie007; 05-07-2013 at 04:56 PM.
    Regards, Stew.....

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    ...local ambient then sets itself to a degree or two above ...
    i don't think he's looking to go subambient - he just wants a programmable thermostat which will keep the temp setting just above ambient. i haven't seen anything like that. but, even if you can't find something exactly, it shouldn't be too hard to build. note - check the TEC threads, a couple of those guys (Ultrasonic and Mindchill) may be capable of building a custom controller to suit your needs.
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  7. #7
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    Chiller with either plate exchanger or larger reservoir is stand alone. The concept is that the ambient and the coolant temperature in the secondary pipework (which supplies the computers) are held at much the same temperatures.

    Read the ambient then control the primary cooling effort by measuring the secondary pipework temps. So no sub ambient temps at the computers.

    I have built supersize rads which can keep temps at ambient +2? in summer. Now I want to explore what happens with a chiller which would be a more compact solution


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    I suppose I went overboard then...

    Take a look at Johnson Controls' website and see what they have... programmable thermostats are usually pricey.

    The reason I went into depth is because I figured you could sample your local environment. Given that its indoors, you should be able to find a standard setting that you can utilize to save yourself some money. It sounds complicated, but it actually isn't. Off hand I can't think of a specific control set, but they're out there.
    Regards, Stew.....

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    Overboard? Here at XS?

    Not at all. In fact it is because I have a grasp of just what introduces condensation to the equation that I want to go this route.

    .... Or should I build the rig with the MB upside down to let the drips fall where they may

    Probably the next step that is to say next years project wil be to build an enclosure for the rig and run the whole thing at say -10?


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  10. #10
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    i'm thinking of doing a chiller setup when i get back to the states later this year - or probably later depending on how long it takes me to actually build my home hehe. my idea is go with a basement design to keep the water a couple degrees below the basement ambient using one of the 1/2 or 1HP aquarium chillers (i know, its costly, but i know too little about the innerworkings of such things to tinker....for now ). just picture a 50 gal fish tank with the chiller keeping the temp nice-n-cool. then running insulated copper piping through the house to the various places i would use water blocks with QD's at the wall to run hose to whatever system i'm using. since the pump(s) and all associated active cooling is in the basement, the only thing in the device itself would be the copper blocks. will likely have outlets in a designated gaming room/office, and the living room (HTPC, PS3/4, XBox, etc). one big advantage is absolutely zero noise. and since the basement is likely a few degrees cooler than the rest of the house, i would be running 3-5C below ambient. (hopefully) not enough to cause condensation. anyway, good luck with your project OldChap!!

    PS: mounting the MB upside down........hmmmmmm.....
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  11. #11
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    And I thought that I was going all out.... No basement here, but that does actually give me interesting ideas.... I'm building mine into a sound insulated chest that should mean it will be a bit quieter than a refrigerator. I may sound insulate the compressor itself if inside temps are alright. >=)
    Regards, Stew.....

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  12. #12
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    hehe - i didn't tell you the really fun part

    using a lot (read: metric crap-ton (R)) of high powered TEC's, create a sub-loop off the 50 gal tank (maybe a smaller 10-20 gal separate tank with its own chiller) for sub-zero benchmarking. using a double-stacked set-up to reach/maintain -50C should be possible (moreso if i can get the chiller to reach near-zero temps). i've been wanting to get into benchmarking and reviewing, and i probably will (at least in some capacity) once i retire in a couple/few years....but, for now, this is all just pipe-dreams - until i can turn it into reallity
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  13. #13
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    Quote Originally Posted by OldChap View Post
    What I need is protection against condensation.

    Looking for a thermostat that reads local ambient then sets itself to a degree or two above (programmable) to control chiller to always run at lowest temp possible for any given ambient.

    Am I describing a product you know about or do I have to build it?
    Hey OC,

    I realize that this thread is a few months old, but considering that the chilling section is usually super slow...I thought I would offer some input.

    First, With many combined years of experience in reptiles, aquariums and PC cooling...I've never heard of a device like you are seeking, so I would think it is something you would need to build for yourself.

    I understand your goal of avoiding condensation, but wondering if maybe I am missing something... Condensation does not occur the moment you hit sub-ambient. It doesn't work that way. There is a margin of non-condensation between ambient and sub-ambient...and that margin is most directly effected by humidity. Higher humidity = condensation sooner/lower margin, Lower humidity = condensation later/higher margin.

    I don't know if you recall my cooling system, but it is basically (in my sig) the "chill, man, chill" with the ghetto chiller removed, and replaced by the "PlateHX Conversion". I run sub-ambient, and combined ghetto chiller, then replaced by the PlateHX Conversion...this system has been going now for a little over 4 yrs. Condensation never crosses my mind. I have run up to 4 OCed crunchers on it, and now I run a single non-OCed rig. The system runs the coolant at ~65F/18.3C.. 24/7/365. The set-point is the same in the heat of the summer, the widely fluctuating temps of spring and fall, and the depth of winter. I could run the system a bit lower during the summer (much higher humidity), and I have run it (short-term) at about 45F/7.2C during the winter (much lower humidity) without any condensation issues.

    All that said: I think all you may really need is a better understanding of the Dew point, and calculators such as this:

    Dewpoint Calculator

    and/or charts such as these:

    Dewpoint Charts

    Can go along way toward easing your mind.

    Let me give you a current example of why I don't bother to worry about condensation:

    My coolant set point is: ~65F/18.3C

    My system is technically indoor and outdoor...the out-building is not temp controlled in any way. But the main concern is at the PC.

    Using this calculator: Dewpoint Calculator

    My current outside temp is about 47F/8.3C. Humidity outside is currently 100%. So, the Dew point is: 46F/7.7C...but, that is outside.

    My current inside temp is 69F/20.5C. Humidity inside is currently 20%. So, the dew point in here is: 25F/-3.8C.

    However, if I crank up the heat to say 80F/26.6C, the humidity is going to remain about 20%, but we will raise it to 25%...and the Dew point will be at 42F/5.5C (at 20% RH the temp is 36F/2.2C).

    So, it's easy to see that I have nothing to be concerned about.

    During the summer, the temps in here average about 78F/25.5C and RH raises to about 50%. So, checking the calculator...the Dew point is 60F/15.5C....Still no reason for concern.

    Personally, I think that a lot of the FUD of condensation in the sub-ambient PC cooling world comes from the reality that the vast majority of people remain above ambient through water-cooling....or are WAAAAAAAAYYYYYY!!!!! below ambient where condensation is a valid concern. There isn't a lot of people in the middle ground of sub-ambient/no insulation/no condensation, so the information really is not understood and/or passed around.

    Anyway, I hope this helps, and, again, maybe I missed your goal, but, if it is to merely avoid condensation on a slightly sub-ambient rig, than I would think that a short study of the Dew point would put you where you want to be...
    Last edited by Naja002; 11-16-2013 at 02:36 AM.

  14. #14
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    THANK YOU !!

    Where I live is by the sea so I have long thought that come rain or shine winter or summer I would have high humidity (relatively). My setup, like yours, revolved around the idea of an inside-outside cooling system.

    Knowing your background and projects I shall re-visit this, while applying the above info.... it now seems more feasible.


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  15. #15
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    Quote Originally Posted by OldChap View Post
    THANK YOU !!

    Where I live is by the sea so I have long thought that come rain or shine winter or summer I would have high humidity (relatively). My setup, like yours, revolved around the idea of an inside-outside cooling system.

    Knowing your background and projects I shall re-visit this, while applying the above info.... it now seems more feasible.
    You are very welcome, OC, and I am glad I could help. Study the Dew point a little bit, play with the slide calculator and I think you will see that it is very feasible.
    Last edited by Naja002; 11-16-2013 at 02:31 AM.

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