Update: Foundation PC Cooling


[gigs], whose foundation-based PC cooling project we covered earlier, has posted his initial test results. There was a large debate going back and forth in the comments as to whether or not this would work, and hopefully this should clear most of it up. He used a 150W fish tank heater to simulated his system’s heat output, and used a quiet fish tank pump to keep the water flowing. Over 8 hours, he was able to maintain a constant temperature 16° C (61° F). While not quite frigid, this would definitely provide ample cooling for normal operation with some headroom for overclocking.

Chart of results after the jump.

[thanks to gigs for getting back with real data so soon]


30 thoughts on “Update: Foundation PC Cooling

  1. its actually a slab-on-grade, and may or may not function as a “mat slab” foundation. and wrt justdiy, i suppose its winter down there so its cool. the slab would be warmed by the sun, but cooled by the air and any evaporative cooling that may be happening. he’ll also have a large, heated house over top of it when its finally running. so its hard to say what annual range of temperatures he can expect to see in the slab itself. what is certain though is that it has a shit ton of heat capacity, and the energy frrom a cpu will easily by sucked up by the slab (provided theres enough residence time in the buried loop).

    its a sweet idea regardless.

  2. I don’t think anyone doubted if it would work or not, clearly it will lower the temperature of the CPU simply because it has such a large surface area.The issue was with how it was implemented, namely using copper in concrete, which is unarguably a bad idea. Using coils of PEX instead of straight copper runs would have been more reliable and offered even more surface area.

    In addition, the benefits of such a large and complex system were called into question considering the thermal properties of concrete and the myriad of additional environmental factors that will come into play. This demonstration proves those arguments had at least some merit, as the performance is certainly nothing worth going through so much trouble for. It could just as easily been done with regular water cooling hardware.

  3. I don’t think anyone doubted it would work, just how well and if a simpler solution would work the same or better.
    While the slab has a ton of heat capacity, it is largely irrelevant to the amount of heat generated by a computer, and is also a fairly effective insulator. It is also a good question as to whether it will have any greater heat dissipation then the same gratuitous amount of copper piping (or even far less) simply placed in open air, as was also discussed.
    Cool idea, but are there simpler superior options? That is the real question.

  4. Please hack-a-day…

    become a bit more scientific !!! ;)

    16 degC means what compared to what ?
    You have to give the room (or in this case the outdoor temperature) to shown how much does both differ.
    16 degC if the concrete is about 30 degC would be freaking cool and by the way proofs one law of the thermodynamic to be wrong

    16 degC for 4 degree means not much cooling at all !!!

    Alternatively, just say he was able to hold a temperature difference of X degC.

    BTW. he gave all those values in his original post.

    Don’t mind just search for something to post :P
    Don’t worry I still like you

  5. Oh I forgot one more point I’m interested

    … what did his wife say ? I mean they are ongoing to build a home and he is just worring about the temperature of this PC cooling project.

    … guess the amount of heat he save on his computer is nothing compared to the amount heat produced by the punishment he receive from his wife for carrying fishtank equipment to the construction site instead of bricks :D

  6. What about running the copper pipe underneath the slab instead. The soil stays very cool and moist and would probably cool better than the concrete. Just bend the copper into the same shape as the one behind your fridge.

  7. PEX is relatively expensive. I’d run a loop of it for only the entertainment value in watching people shake their heads as I describe the method I used to cool my computer’s CPU. PEX or Cooper, given the thermal conductivity of concrete it wouldn’t take very much tubing at all. this is not like you are circulating hot water for space heating where you desire to heat the slab uniformly.

  8. I feel sorry for the guy that did this. Within about 2-3 years, his copper tubing will start leaking around the edges where it is coming out of the slab. If you walk around and new housing projects. You will notice that the copper tubes for water are:
    1. coated or
    2. have a plastic sleeve around it.
    Fresh concrete/cement will always have a reaction with the copper. It will eat it up. Anyone that’s worth his salt in construction knows this.

    Source: 10 years of experience in construction.

  9. Lotta should haves in this, but it’s still going to be a couple/few years worth of awesome just like it is.

    Just use it until it fails and put a better one in your next house! :D

    it wasn’t THAT hard to set up and it’ll get some use so what’s really the harm here?

    when the pipes start leaking you pump it out as best you can, cut them off flush with the floor and cork ’em!

  10. Sweet setup, glad it is working so far. I’d say 16c water temps are a success!

    The non-science in me would guess this to be a pretty good cooling system, considering that concrete slabs that aren’t in the sun always feel cold :). Even if it were to work no better than a copper loop of the same size in the air, at least it’s out of the way, hidden in the floor, and super cool.

    As for rusting away in the future, I don’t personally know of anyone who has used the same PC cooling system for 5+ years. So you’re right, if you’re loosing coolant, cap it off and forget it.


  11. Bah a properly designed Air/water exchanger will do all he wants. Most Pc overclockers half ass it. I pull more heat out of my intake air on my turbo car than any of you PC guys can generate with your little processors.

  12. 2 things:

    First: copper loves to corrode inside concrete (should have used steel pipe in the slab). I’d give that loop a decade max before it starts leaking.

    Second: heat exchange pipes will destroy a slab quickly if not prepared for. Now this is just a small loop for a computer, but it doesn’t look like they have even taken basic measures such as sealing around the pipes.

    If this was my slab I’d fill in the copper and just run a plastic hose out into the dirt. Better cooling and it doesn’t destroy the slab.

  13. question: Lets say the pipe does corrode and start leaking? Would the area around the pipe (the concrete) act as another pipe since we can assume that the pipe was fully enclosed with concrete? I understand that there will be sand and shit after that fact (a filter could fix). Would you suggest every year or so pushing a coating mix though the tubes (to re-seal)?

  14. http://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

    “It is completely acceptable to bury/embed both hard drawn and annealed copper water tube in concrete.”

    “According to the Portland Cement Association the interaction of copper with both dry and wet concrete should not cause a corrosion concern.”

    i have no experience with copper in concrete, but why did i just find a complete contradiction to what all the commenters are saying?

  15. http://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html

    Same website. It also states this:

    “However, copper should be protected when it comes in contact with concrete mixtures that contain components high in sulfur, such as cinders and fly-ash, which can create an acid that is highly corrosive to most metals including copper.”

    No one really knows how high the content of sulfur or fly-ash is a mixture until it mixed at the plant. Even then you you should always prepare for the worst. That’s all I’m saying.

  16. bum bum buuuuuuuummmmmmmmmmmm

    will cannily co-opted copper corrode on the pipes that peter packed previously?

    Will Sam get the message the laura tied to the back of sam’s goat dave?

    What does a goat have to do with this?

    all these questions and more on the next hacker’s drama theater!

    brought to you by altoids and tessco

  17. Thats freaking funny….

    so many high pro constructors know it better… reading all these posts remembers me of discussions between my father and his mates :D

    get real….

    1. Corrode yes but speed is much limited.
    2. Destroying the slap… oh my god 99% of all concrete buildings are going to collapse :D

    If there is a leakage in 10 years… pure some of this bares leak stuff inside which you will find in a DIY shop for your car cooling system.

    If it leaks 20 years later…. well

    0. Maybe human kind is doomed or we are just more amazed to make a good wooden fire and create sharp triangular stone knifes
    1. Maybe PCs in the today form are gone already
    2. Maybe you have to cool them with liquid nitrogen
    3. Maybe gigs bought one of this “home server central heating combination” units :)
    4. If he is still thinking to use the tubes…

    .. he will simply put some of those little freaking nanobots inside and let them replace the damage…

    he can easily get and use them since there are articles about them on hack-a-day in 2025, 2027 and 2029

    and don’t forget, since it is hack-a-day to read about the arduinno based nanobots from 2019 and 2021

  18. I give this guy some credit. Personally, when I do buy a house, I want to do a similar project with a long length of buried tubing for cooling the house in the summer. It probably won’t have the same capacity as an air conditioner, but I’m betting it would save a good amount of electricity over a traditional a/c unit.

    Case in point: my dad has a barn with a thick cement floor that he’s used as a garage for many years. The ground floor is almost always a good 10 degrees cooler than the outside air in summer. In winter, the concrete modulates the temperature swings so that a negative 20 degree Fahrenheit temperature at night isn’t nearly as cold.

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