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Using a House's Concrete Foundation To Cool a PC
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!"
How are you going to explain that if you want to sell that house???
Ahhh...the great dumpster continuum. Many a free computer will be found there. -- sowth (748135)
that is what I want to know.
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The steel rebar and the copper pipe being in close proximity will make them act as electrodes on a battery. This will cause the steel anode to slowly be destroyed by the chemical reaction.
Is it a practical concern in your case? I doubt it, but if they haven't poured yet, it wouldn't hurt to wrap the copper pipe in some PVC tape. This will reduce the thermal coefficient though. Maybe just do it where it passes within a couple inches of the rebar.
Just don't plan on being able to move your desk.
Copper would be a waste of money tho. Use one of the many types of plastic hose already made for this application.
Yes, because plastic is a muuch better conductor for heat than say, copper.
I work for the Department of Redundancy Department.
since those aren't degrees.
If you were pouring the concrete, why didn't you put it outside of the concrete? 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 to help mitigate costs in heating and cooling.
My work here is dung.
Use PEX instead. Copper will eventually fail. Look at the material that is used for radiant flooring.
Without proper thermal throttling, your roof could come off, even with a passive heatsink.
I think Antec makes a two-story-high fan that might work perfectly in such a situation, but the neighbors might be bothered by the LEDs.
In most areas of the country, it's not a question of if but when your house settles and puts some nice big cracks in your concrete. Whether or not it would be a enough to damage the pipe is another question, but if you're relying on it to cool a semi-expensive piece of hardware, I might be a little nervous about it.
Also, seems like this will severely limit your options for where to put your computer physically.
Are fans really that horrible? They make them fairly quiet now. Is that extra .4 Ghz really worth all that kind of effort?
6 ft down doesn't actually provide much cooling. If you want a "neutral" temp, you need to go well underneath the slab.
Plus, you're "sinking" to a temp of 40-50F, and you have to consider that the concrete itself is a fair insulator, so you won't actually lose as much heat as you hope.
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.
"There is much pleasure to be gained from useless knowledge." - Bertrand Russell.
Ground Source heating/cooling is a pretty nifty technology, and can be applied to a whole house HVAC system, rather than just a computer. It obviously requires more tubing than a single computer would, and in most climate will still require some supplemental heating/cooling for more extreme temperature days, but it's still awesome. It does have some upfront costs though.
This idea to do it for a particular computer is a clever idea. I personally wouldn't want the pipe to actually be moving horizontally through my slab, I'd rather dig as small a diameter hole as is possible, but deeper under the slab, and just have the line penetrate the slab vertically. The deeper you go, the more stable the temperature becomes, and the less hollow copper pipe you've got running through the slab, the less you weaken it.
One time I threw a brick at a duck.
And you haven't thought through the consequences yet? That my friend is a project that has failure written all over it.
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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).
Why? It's very similar to what they do when laying radiant heat into the floor (which is very nice btw, over ducted heat, helps with breathing problems).
Also, like a previous comment suggesting, maybe you should look into radiant heat tubing over copper.
Apart from the fact that concrete attacks copper. All copper water pipes placed in concrete have to coated in plastic to protect them (at least in the uk).
I would use underfloor heating plastic pipes which are designed for this job. Sure they would need to be longer to get the heat transfer but the price would be similar and would be far less likely to leak. They certainly work fine in getting 6kW of heat into my house so absorbing a few hundred Watts would not be a problem.
wot no sig
Houses have been built with copper pipes and steel rebar and rewire in the slab for decades now without any electrolytic effects showing up.
Once the concrete is cured, it is no longer an electrolyte. Concrete is not a great electrical insulator, but it's not a great conductor either.
Putting moderation advice in your
Getting rid of heat by dumping it into the ground is a great idea.
The problem is, you're dumping heat into your house's slab, not the ground. You need to put the pipes several feet underground.
All this is is a mild underfloor heating system. If that's what you're trying to achieve, ok, but if you're also paying for air conditioning to remove heat from the house, this is probably not worth it.
Putting moderation advice in your
Unless there's a specific code against it there's no reason why he wouldn't be able to. I work with the Building and Plans department at a county-level government office (I actually admin their software system). When I went through their checklists to add to the new system, it was mostly things you're supposed to do, rather than things you're NOT supposed to do. As long as you do everything on the list you're good to go.
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Negative.
http://www.copper.org/applications/plumbing/techcorner/problem_embedding_copper_concrete.html
They use PEX because it is cheaper and easier to install, NOT because of its longevity.
"As God is my witness, I thought turkeys could fly." A. Carlson
I live in the midwest, and did the same thing 4 years ago, when I had my house built... I use a heat-pipe to fluid thermal exchanger on my ESXi server as well as my gaming rig.
It will in no way harm your resale value, and if your inspector has a brain, it has no impact on the inspection...
Due to expansion and contraction concerns, I had that small (8`x8`) portion of the concrete isolated....
That first link is so bizarre, sitting within a post which otherwise seems very logical. My brain is short circuiting as it tries to find the connection between underground piping and spinach pizza.
I got a bunch of raised eyebrows when I had two four-gang electrical outlets (one from either leg of the house power) and an exhaust vent fan installed in one of my closets when we built our house. I wanted it for a server farm but couldn't convince anyone that I wasn't going to be farming something else.
The cost of that cleanup, of course, will be borne by taxpayers, not industry.
Scratch that. Greater detail on the pics.
He's barely going down at all. Maybe two feet deep, tops. His slab, at that depth, is going to have an insignificant (less than 15F) temperature difference with the external.
Now if you go down SIGNIFICANT distance, you can reach an earth-neutral temperature. The further down you go (until you reach a stable point, which will depend on your local ground type) the cooler you will be.
If he were to go down 10+ feet or so, and then set up the circuit like he is indicating, it wouldn't be too bad. As it stands, he's gonna have one of the most inadequate foundation slabs I've seen in any case, and his "copper pipe cooling" is not going to give him nearly the cooling he is hoping for. I hope to god he isn't in an area with frequent foundation shifts, or he's fucked as it is, copper piping or no.
Talk about a heat sink. I'm a little surprised that this sort of technique is not more widely adopted at places like data centers; geothermal or water-source heat exchange, especially for cooling. I have been looking at using a water-source heat pump system to replace my electrical resistance heating/air conditioning system. Big incentives from the government.
Best regards.
Yeah, that 6m of copper tubing will probably make the house explode, right?
Learn about Photography Basics.
Well, your habit of using the acronym "THC/IP" did rather give the game away....
I rented a house in Kentucky that had this problem. The house was built with copper pipes embedded in the foundation for water, but to save money apparently the builder had just put bare copper pipe instead of putting it in plastic conduit. About 5 years after the house was built, the pipes started failing (in my case, it was a pipe that led to an outside faucet I never used, and I only discovered it when my water bill went from its normal $20 to about $280 one month).
Fortunately, the landlord in my case was the builder, so he sent a team out to reroute all the pipes up through the ceiling (which was a major mess, but the workers were really careful with my stuff and used sheet plastic generously to contain all the drywall dust, etc) and refunded my water bill for the month. He also replaced all the carpet in the house, since the workers pretty much ruined the carpeting running the new water pipes. So after a week or so of hassle, I had a freshly-painted house with brand new carpeting.
Apparently (as it was explained to me by the landlord) bare copper *can* sometimes work in concrete, but it depends on the acidity of the concrete, which probably depends on the stone and filler used. The landlord admitted he messed up and didn't measure the acidity of the concrete (and he had built and sold a lot of houses in my neighborhood, so he was looking forward to a LOT of repairs like this).
In any case, lining the copper with something is probably a good idea, even if it does reduce heat exchange. Or just use radiant heat pipe as the parent suggests.
After all, there's the heat generated by a computer (maybe 150 watts) to deal with, and 6 meters of pipe. With that much pipe, just the copper exposed to air would probably dissipate enough heat without needing forced air, so exchanging the heat through plastic into a concrete biomass should work just fine.
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This is exactly what I came in here to say. Your concrete isn't some magical source of coolness: it obeys the laws of thermodynamics just like everything else. And a mere 6 meters of pipe means that that warm water is going to circulate frequently, warming up the concrete and making your computer overheat.
Putting the pipe in the slab won't have any effect on the slab or the resale of the house, but it probably won't have any effect on your computer either.
If you want to try some kind of fan-free passive cooling, you'd be better off putting in a swimming pool, and running some radiant pipe in the deep end...Fractionally heat your pool, and significantly cool your computer (unless you live in a really hot area).
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
"Also, like a previous comment suggesting, maybe you should look into radiant heat tubing over copper."
This. I used to live in Alaska and radiant heat slabs were very common. The problem was making sure they never went without heat in the winter. If they did, you ended up with burst pipes and a cracked slab. Big headache.
The fix is burst-resistant flexible tubing. There is a product called Aqua-pex that fits the bill perfectly. Does not burst when frozen, has a 100-year warranty and is easy to install as it is flexible.
The other problem with copper in concrete is that the concrete itself is corrosive. It WILL eventually eat through the pipes leading to all sorts of headaches. Usually, when this happens the only fix is drain them and cap the pipes. Most people in Alaska with radiant flooring, even when using Aqua-pex, lay down a second circuit in case there is a problem. They simply hook up the back-up.
Another suggestion. If you DO use copper tubing, use alcohol, or some other coolant such as glycol, rather then water. You will have better heat transfer as well as less corrosion. This is, of course, assuming you have a closed loop circuit (would be foolish to have anything but).
3" cover is most certainly not required. Most commercial floor slabs are 2.5" concrete on 1/2" form deck (9/16 for the pedantic). A 4" slab will have two layers of rebar in it - either as WWR (gauge wire on a 6x6 grid) or as actual rebar up to 1/2" in diameter. That means as little as 1-1/2" of cover over the steel.
The 3" you may be thinking about is clear cover for steel reinforcement when slabs are cast against earth. In that case, it's to minimize water infiltration and protect the steel from corrosion.
Freezing of the slab is theoretically possible in a very, very cold environment, but not unless the house is left unheated for an extended time as subzero temps and the typical ground temp is below freezing (an ice lens would have to be able to extend from the exterior of the slab all the way to where the embedded pipes are). In that case the whole house would have to be "winterized" with all lines drained.
IAASE (structural engineer), BTW.
Is it just my observation, or are there way too many stupid people in the world?
http://www.copper.org/resources/properties/protection/underground.html
That site says that concrete does not corrode copper. My experience seems to back that up. (Yes, I've built and I've demolished buildings.)
One problem that might cause corrosion, is allowing anything to be electrically grounded through the copper. Read the link. Using a double insulated pump would be a good idea, but not necessary.
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PS: rechecked location. He's in Tassie, Australia. Very coastal, very similar temperature-wise to coastal US temps. Yeah. This is gonna be REAL disappointing for him. The laws of thermodynamics, much like gravity, don't play very well with wishful thinking.
So the solution is to wait six months and then buy a wireless heat sink?
You've obviously never been lied to about birth control then.
Okay, I get it, he got the informative for the Aqua-pex. Problem is, Ethlyene glycol decreases water's ability to transfer heat. What it does is raise the boiling point, lower the freezing point, and retard corrosion. Replace your coolant mixture when a voltage measurement between fluid and pipe exceeds one volt.
We used to use alcohol in radiators, because it does all that stuff and increases thermal conductivity, too. But there were some problems with fires when people used too much. So we just stopped. If you put 100% ethlene glycol coolant in your cooling system it will work, albeit at a very poor efficiency. You might get away with it in the winter.
If you want something you can just use a little of, there is Red Line Water Wetter, which is often used in racing in all-alloy systems, in which it is sufficient to prevent corrosion. It actually also increases thermal transfer.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Coper is the wrong thing for this application. The contact of your rebar to the copper will setup an galvanic corrosion problems. http://en.wikipedia.org/wiki/Galvanic_corrosion Under floor heating systems use PEX like everyone is suggesting. Get some and use it. Get the kind with the aluminum in it. The heat transfer is better. If it's too late to change then you must use something kind of antifreeze in this system. Even with PEX I'd use it because water can still burst PEX and crack your concrete.
It all starts at 0
exchanging the heat through plastic into a concrete biomass should work just fine.
For the typical house built on top of a concrete mass, exchanging heat with it may work fine.
But if your house is built on on top of a concrete biomass, RUN! IT'S ALIVE!! RUN!!!
Now that's a protocol I can endorse! How many grams per second do you typically get when downloading? Is there a flat monthly fee? What are good ISPs* that don't do traffic shaping? Is it easy to encrypt your packets and do you have to pay extra for the aluminum foil/scent resistant wrapper? Can you download across state lines? Or even from Ethiopia?
*Indica Service Providers
Just trying to pass on my own experiences with Alaskan environment and cooling/heating systems.
I plumbed my ENTIRE house with Aqua-pex (no pesky building codes to deal with). And before I did so, I bought a 20 foot length, filled it with water, capped both ends, and set it outside at -40F. It never burst. Even after a few temp swings of about 50F, there was NO noticeable deformation. I seriously doubt you are going to experience such extreme temps. The other advantage of Aqua-pex is that you do not need any joints IN the slab. Any joints in the circuit simply become another possible location for a leak. Aqua-pex also has a very high shear resistance, so if you are in a earthquake prone area, it provides some protection in that regard.
As far as coolant, notice I listed ALCOHOL first. Yes, glycol is not a very good conductor of heat, but it is better then burst pipes (if you insist on using copper). The advantage of alcohol is that it will absorb any moisture you fail to remove from the circuit and dilute it, rather then just have that water pool in one location and continue it's corrosion.
Not sure if anyone else mentioned it, but you need to increase the thickness of the slab (dig deeper dude) wherever you have the circuit as the circuit itself becomes a weak point in the slab. Think perforated paper.
I do not think it will be an issue here, but the one thing I DO know about Aqua-pex--it cannot withstand long-term UV exposure. It will become brittle if exposed to UV light for any length of time. The solution is to simply wrap it with aluminum tape in any location it is exposed, such as outdoors in sunlight.
Why is it that we haven't built datacenters in places with natural cooling. gives a new meaning to the phrase, sent to siberia.
I know I am not the only one with this obvious Idea.
music lover since 1969
I don't get it - are you suggesting that geothermal exchange violates the laws of thermodynamics? If so, please explain your reasoning.