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Hardware Hacking Upgrades Build

Using a House's Concrete Foundation To Cool a PC 465

Posted by timothy
from the thinking-deeper-than-built-in-cable-drops dept.
Agg writes "Well the slab gets poured on Wednesday so I thought I would sink 6 meters of copper pipe in the slab so that I can run my water loop through it when the house is finished. I hope to have water year round at about 16deg [about 61F]. No need for radiators or fans with chilled water coming straight out of the slab!"
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Using a House's Concrete Foundation To Cool a PC

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  • by jawtheshark (198669) * <slashdot@nospam.jawtheshark.com> on Wednesday August 26, 2009 @01:42PM (#29205745) Homepage Journal
    How are you going to explain that if you want to sell that house???
  • Units... (Score:1, Insightful)

    by Brett Buck (811747) on Wednesday August 26, 2009 @01:43PM (#29205763)

    I presume you mean 16 degrees centigrade, as opposed to degree Fahrenheit, or Kelvins or Rankines.

          Brett

  • by Shivetya (243324) on Wednesday August 26, 2009 @01:44PM (#29205779) Homepage Journal

    that is what I want to know.

  • Re:Units... (Score:2, Insightful)

    by Anonymous Coward on Wednesday August 26, 2009 @01:45PM (#29205789)
    i assume you mean 16 degrees Celsius, it hasn't been centigrade since 1948.
  • Cool (Score:3, Insightful)

    by flaming error (1041742) on Wednesday August 26, 2009 @01:47PM (#29205837) Journal

    ... literally. But why limit yourself to PC cooling? Turn the slab into a big radiator and pump air from the upstairs/attic through - you can moderate the temperature of your whole house.

  • by seanadams.com (463190) * on Wednesday August 26, 2009 @01:50PM (#29205891) Homepage

    Who cares, it's a couple pipes sticking out of the slab. Cut 'em off if you're worried about it.

  • by eldavojohn (898314) * <eldavojohn@nOsPam.gmail.com> on Wednesday August 26, 2009 @01:50PM (#29205911) Journal
    If you were pouring the concrete, why didn't you put it outside of the concrete [japru.com]? You would probably incur less structural risk ... although I doubt a pipe that small would have much effect. More and more people are building new houses with geothermal exchange [geocomfort.com] to help mitigate costs in heating and cooling.
  • by Pyrion (525584) * on Wednesday August 26, 2009 @01:52PM (#29205945) Homepage

    Depends on who you've contracted the work out to. I'm not kidding. Some inspectors "know" the contractors such that they only do a cursory inspection of the finished product before signing it off.

  • by Cmdr-Absurd (780125) on Wednesday August 26, 2009 @01:54PM (#29205985)

    How are you going to explain that if you want to sell that house???

    Call it radiant floor heating?

  • by Smoke2Joints (915787) on Wednesday August 26, 2009 @01:54PM (#29206007) Homepage

    not only that, but i would have thought that driving the copper pipes into the water table would do much more for cooling than surrounding it in concrete.

  • by OzPeter (195038) on Wednesday August 26, 2009 @01:58PM (#29206091)
    And you haven't thought through the consequences yet? That my friend is a project that has failure written all over it.
  • by Anonymous Coward on Wednesday August 26, 2009 @01:59PM (#29206095)

    Copper makes the most sense in this application.

    Copper makes the most sense for conducting heat. BUUUT this is a moronic idea. If anything goes wrong there is no way to fix it short of breaking through the concrete to get to the pipe. The house could settle or shift and crush or break the pipe (or there could be an earthquake).

  • by kevinNCSU (1531307) on Wednesday August 26, 2009 @02:02PM (#29206169)
    By having the pipes come up between the walls and knocking the valves back in and plastering over them if they don't want them exactly as the forums discuss? To be fair though I'm not sure why your comment is modded as a troll, it seems an honest enough question.
  • by orsty3001 (1377575) on Wednesday August 26, 2009 @02:04PM (#29206211)
    First house ever built on land that needed a sacrificial piece of metal.
  • by Zantac69 (1331461) on Wednesday August 26, 2009 @02:15PM (#29206371) Journal
    When I first took a look at this, my thought was "COOL! (no pun intended) Use the slab as a heat sink just like they do for houses in Sweden!" But my engineering logic kicked in and alarm bells went off.

    1 - Implant in concrete for the lose. There is the possibility for reaction with voltaic interaction with steel as well as the chance for any reactions with the concrete.
    2 - Its pretty permanent - so its not like you can relocate to the other side of the room.
    3 - Electrical conductivity. Lighting? Say no more.
    4 - Real heat transfer coefficient issues. Yeah, there will be some conduction between the copper and concrete, but if there are air gaps, transfer goes to crap since there will not be any air movement.

    So from an engineering POV, I would scrub it. Geothermal cooling for a PC sounds cool - but its gratuitous overkill.
  • by Goaway (82658) on Wednesday August 26, 2009 @02:16PM (#29206397) Homepage

    I don't know about you, but if I buy or make something, it's for me. I'm not there to take care of it for the next owners. If I wanted that, I'd rent.

  • by blueg3 (192743) on Wednesday August 26, 2009 @02:25PM (#29206551)

    You're limited by the efficiency of the heat moving through the copper strap. You'd probably want a heat pipe. Even then, keep in mind that most heatsinks actually have quite a large surface area, so moving it to your case doesn't buy you much. (Assuming you're using the case-as-a-heatsink for thermal exchange. The case isn't really worthwhile as a thermal reservoir.) Heat pipes are great for moving heat to an easier-to-cool location, though -- which is what is often done with laptops.

  • by lwsimon (724555) <lyndsy@lyndsysimon.com> on Wednesday August 26, 2009 @02:36PM (#29206701) Homepage Journal

    Yeah, that 6m of copper tubing will probably make the house explode, right?

  • by walt-sjc (145127) on Wednesday August 26, 2009 @02:40PM (#29206777)

    Copper is also wicked expensive if you priced it out. You are FAR better off running 2 to 3 times more super cheap PEX than copper. Copper also can't flex very much before cracking which is a big deal when you are running it to something that WILL get moved. It also subject to dielectric corrosion.

    Just a few hundred feet of plastic tubing heats my entire house even when it is -25F outside. PEX tubing is used almost exclusively in modern heating and cooling coil systems (underfloor and underground.)

    Copper makes sense when the application doesn't allow for long lengths of tubing when you need maximum dissipation in the minimum space. That is NOT the case here which, with the other disadvantages of copper, make it the WRONG choice in this application.

  • Re:Ice cooler! (Score:1, Insightful)

    by Anonymous Coward on Wednesday August 26, 2009 @03:34PM (#29207653)

    Jeez, this all seems quite a complex way to cool a computer. If only there was some way this could be neatly packaged inside the computer itself.

  • by idontgno (624372) on Wednesday August 26, 2009 @03:45PM (#29207827) Journal

    All of these subjects were touched on within (all 11 pages) of the discussions. I know that "tl;dr" is a way of life here, but really, sometimes you can learn stuff.

    Galvanic corrosion was dealt with by insulation (standoff "chairs") air gapping (or concrete-gapping) the steel remesh and the copper plumbing. Chemical corrosion was discussed; consensus was that it's an issue with a timeframe of decades.

    Permanence was not explicitly addressed, but the homeowner's idea was that it's his dedicated PC room; who would make him relocate anything?

    The entire lightning-strike angle was properly laughed off. If you get a lightning strike close enough to energize the floor slab, you have bigger problems than the cooling loop. And the interconnection approach to the PC seemed to be evolving to a dual-loop system, with a heat-exchanging tank. Also, flexible plastic interconnects. Honestly, is this lightning risk even remotely credible, given that most computers are directly connected to MILES of conductors (power lines, cable or telephone lines), some of which is suspended in the air begging for a direct lightning strike.

    As to heat transfer, again, if you leave large bubbles in your concrete, you have larger problems than a few inches of non-contact between the heatpipe and the thermal mass. And with the dual-loop system proposed, the exchanger tank functions as a buffer.

    No, if I were to guess, I'd speculate that the real problem would be that the concrete doesn't have infinite thermal mass or spectacular thermal conductivity within itself. Run hard enough long enough, the concrete in immediate contact with the heatpipe would begin to warm, killing its cooling capability. But I'm no thermal engineer, so I dunno.

  • by Rob the Bold (788862) on Wednesday August 26, 2009 @04:07PM (#29208149)

    I don't know about you, but if I buy or make something, it's for me. I'm not there to take care of it for the next owners. If I wanted that, I'd rent.

    Meanwhile, to the rest of the people in this reality, re-sale value is very much a concern with home ownership. If the cost of the modifications matters, then the future ramifications of the value of that house matters.

    Oversimplification and ridicule is not insightful.

    I'm selling a house right now. Buyers have absolutely no interest in the mechanical systems of the home, and only care about the structure if a wall is out of plumb or they can see through a supposedly solid medium. The only important thing to them are sufficient beigeness of the walls inside and out, sufficient shininess of the flooring, and sufficient Tuscanness of the fixtures, tile and hardware. You might think people would be more interested in the guts, but we're /.ers here, and most people are not. Also the $8000 tax credit has house noobs coming out of (in to?) the woodwork.

  • by LordKronos (470910) on Wednesday August 26, 2009 @06:33PM (#29210197) Homepage

    The contact of your rebar to the copper will setup an galvanic corrosion problems.

    He's already said in the forum "Im going to separate the copper so that it is not touching the steel reinforcing bar." Of course, that won't protect him from the concrete (as others have pointed out) but the rebar won't be an issue.

  • by Dun Malg (230075) on Wednesday August 26, 2009 @06:50PM (#29210319) Homepage

    "Exothermic reaction" means the concrete will be emitting heat and therefore will not make a good pc cooler until the curing is complete.

    How much heat do you think curing concrete gives off? By the time it's hard enough to build on, environmental temperature has a much greater effect on the concrete temperature than any residual curing. Honestly, it never ceases to amaze me how slashdot geeks don't allow having no practical experience with something (e.g. pouring concrete) stop them from drawing extrapolated conclusions therefrom.

  • Re:Cool (Score:4, Insightful)

    by flaming error (1041742) on Wednesday August 26, 2009 @09:29PM (#29211551) Journal

    I don't get it - are you suggesting that geothermal exchange [wikipedia.org] violates the laws of thermodynamics? If so, please explain your reasoning.

  • by plover (150551) * on Wednesday August 26, 2009 @11:45PM (#29212431) Homepage Journal

    Aside from not worrying about the slab breaking and damaging the pipe (the rebar he shows in the picture will prevent that) I don't understand why people are so afraid of concrete? Ever put a toilet or shower in a basement? You take a saw, cut a hole for the fixture, cut a trench to the drain pipe, fit the new pipes, pour replacement concrete into the hole and trench, and trowel it flat. It adds a few hours or so to the job, a few bucks for renting a wet saw, some sacks of concrete, and a messy wheelbarrow to clean up. It's hardly unfixable. And it's certainly not rocket science.

    There are no dangerous cables embedded in a slab that would lash out and kill you if you cut them. It's not like homeowners use post-tensioned concrete for ground-level floors! About the worst damage you would do in an average home would be to nick an existing buried pipe, and you'd see that problem instantly as you clear the rubble from the trench. (You'd probably smell it even before you saw it.)

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