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cooling computers and heating water / thermal store??

Discussion in 'Plumbing and Central Heating' started by miless2111s, 10 Mar 2014.

  1. miless2111s

    miless2111s

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    I have a bunch of computers which currently put out an uncomfortable amount of heat into the air. Not only isn't this very nice but it is wasteful. I have been kicking around the idea of trapping the heat by liquid cooling and feeding this hot fluid (probably oil) into a heat exchanger to play some role in either heating a thermal store or pre-heating water as it enters the boiler??

    I am very new to all this and having a quick look on this forum there seems to be a wide range of views on the usefulness of thermal stores.

    As a side note I am also planning to have Solar Thermal at some point in the future. We currently have a Gas Boiler and a megaflow unvented system.

    Obviously once the thermal store (if this is used) has got to a certain temp it will no longer be useful to cool the computers however I expect to have a thermostate to divert the output from the thermal store feed to some other rad to cool the oil before it returns to the computers thus protecting them from over heating.

    Where I am struggling a little is understanding how best to use this heat and how to specify what I need + what benefit this will actually give in terms of heating the water / house.

    At the moment the three computers consume around 3kw however in the future it maybe up to 5kw or above and run 24/7.

    I am positive that I haven't given enough information yet so ask questions and I'll do my best to answer :)

    Thanks

    Miles
     
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  3. Hessles

    Hessles

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    Sounds like a nice idea in principle but I can imagine it being an expensive nightmare to implement. Computer water cooling already exists as do the cooling blocks that need to sit on the chips but the piping is small and runs on small dc pumps with a special coolant. You'd need to marry this to a tank with a coil (likely 22mm piping) somehow.

    Good luck to you if you try it!
     
  4. muggles

    muggles

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    Short answer?

    I'll cost you far more to install than you'll ever recover in money saved I suspect
     
  5. miless2111s

    miless2111s

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    Sorry, knew I'd missed something out! I'm using immersion cooling where the whole thing is immersed in oil so I don't need to fanny around with individual components and can pump as much oil as I need using robust technologies rather than plastic pipes and fittings.
     
  6. JohnD

    JohnD

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    what temperature does your coolant reach?

    how many kWh do your systems use, in total, per day?

    Are you seriously saying that your computers use 1kW each?

    What sort of machines are they?
     
  7. miless2111s

    miless2111s

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    This maybe true, I'd like to understand how to check this and the alternative is to just dump the heat outside or worse yet be baked inside by the current site cooling! :)
    If the heat store (assuming this is used) is costed as part of the solar hot water buy then element will be reduced... Man maths ahead :)
     
  8. miless2111s

    miless2111s

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    The graphics cards are the hot bits and at the moment they are controlled to 80 degrees Celsius however I think that when people use water cooling they tend to be at around 50, maybe lower. The honest answer is that until I build a prototype I will not know for sure but I'm expecting it to be between those figures.

    At the moment I have two computers up using a peak of 1200 and 1600 watts and generally running fairly close to these figures. A third should be on line in a week or so. They run 24/7.

    Thanks

    Miles.
     
  9. muggles

    muggles

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    OK, it can be calculated, but you'll need to get your oil bath set up for your computer first (a bit of expense in the name of research). Put your computer in, along with a sensitive thermometer, and fire it up. Run it for a known period of time, say two hours, and note the difference in oil temperature. You'll need to know the specific heat capacity of the oil. From this you'll be able to work out how many watts of heat the PC has generated...if your maths is good enough ;) Heat losses due to convention and radiation can be ignored as these would still occur if you had your system connected to your thermal store
     
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  11. muggles

    muggles

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    You should aim for 20ºC operating temperatures...
     
  12. miless2111s

    miless2111s

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    OK in principle I can do this, but not for a few weeks. In the mean time the watts the systems are drawing at the wall will be mainly being converted into heat surly? There's some noise and kinetic energy losses in the fans (5 chassis fans and 10 on the cards) as there's no hard drive etc...

    Is there other stuff which can be considered or designed in the mean time?

    Thanks

    Miles
     
  13. miless2111s

    miless2111s

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    Wow! Really? That's amazingly low - is this the optimum for performance?
    Thanks
    Miles
     
  14. mogget

    mogget

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    In my previous job as a computer builder/repairer I learnt that the core temperature of any IC should be kept below 75-80 degC as above this degradation of the junctions / electromigration can occur. Below this there is little performance benefit to going any lower unless there is a system that ramps back the performance under these temperature conditions.

    This was a long time ago, but I don't think the chemistry of silicon, gold, and copper has changed much during this time. So if using air cooling, you should aim to achieve 20 degC but you will never achieve it if the room is at 20 degC. We did some experiments with peltier cooling and found no performance benefit except that we could clock ICs at a higher frequency before they fell over, if they were running cooler. Also if you run below room temperature, condensation becomes a problem. We decided not to offer it on our PCs for sale.
     
  15. Aragorn84

    Aragorn84

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    I presume this is a cryptocurrency mining setup?

    I think you should consider that for maximum returns you want to keep it all as simple as possible and minimise outlay. If you spend hundreds of pounds extra trying to liquid cool these machines it just means the whole setup takes even longer to break even. Theres also then more to go wrong, when you find components arent "oil safe" and fail, and also the potential for leaks, either of oil, or water.

    Furthermore, oil immersion instantly writes off the hardware in sofar as resale or warranty goes.

    Your pushing these cards flat out 24/7, some WILL fail, and its yet more money down the drain if you cant then simply return them for replacement. Similarly if it all goes pete tong, and you decide to sell up, shifting 15 graphics cards is hard enough never mind 15 oily minging graphics cards!

    In the winter, the easiest thing to do is put the machines in a location that you can benefit from the heat emitted and offset some of your central heating input. So putting them in the garage is pointless, but putting them in the hallway or dining room or whatever where the heat can be used to actively warm the house is a far better idea.

    Sensible design and selecting the right cards will ensure they run at reasonable temperatures without having the fans maxed out (ie noisey) For instance an Asus 280x will tick along at about 40% fan and maintain <70c, whereas some of the cheaper stuff like powercolor will be maxed out at 85% fan and still be over 70c. 270's also run very quiet as they're emitting about half the heat of a 280 but the heatsinks are only slightly smaller.
     
  16. andytw

    andytw

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    Please confirm you plan to completely immerse the computers in oil ?

    andytw
     
  17. miless2111s

    miless2111s

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