Topic: Submersing a rig - page 4. (Read 5768 times)

Not sure what you mean. If you think there is not enough plants in the water, keep in mind thats early spring before most of the plants and lillies surface, and right after a thorough cleanup. in the summer you can almost walk across the pond without getting your feet wet .

Definately not.  Its just a waterfall, all that matter is the surface area you produce, and that isnt much. Moreover, insummer inside the shed it already gets to 35+C without help from mining rigs, and I were to dump all the heat in there, it would get a lot hotter. And then you only have (hot) air to cool the oil, thats not nearly as efficient as cool water.

That is a baller pond. Start the aquaculture op!

Above 40C? Heh. Maybe I need a picture here to help you visualize 50K liter. Here is half the pond half drained for maintenance this spring:






A few gpus arent going to cause that to overheat .

Im much more worried about leaking. Ill probably add a floater switch that shuts everything down if the oil level drops. And probably an electric valve as well.

I've done a lot of diving with both wet and dry suits ('fuck Lake Superior' is all I can really say about that), I just wasn't hip to how the liquid fit into the insulating picture. I suppose I should have pieced it together, what with needing a new wetsuit every six months due to compression. Southern California's got some chilly water, but dry suits absolutely suck...turn your head too far and you're wearing wool soaked with icewater.

I was an AAUS diver for a bunch of years and people are always disgusted by the concept of pissing in your wetsuit...all I can say is when you have to dive at five in the morning in 10c water, it is the only relief you are going to get...even a 7mil with an insotherm and a hooded vest won't keep you warm in that shit.

Wouldn't an fish tank filter :



do just as well if not better than a radiator at cooling down the oil. You would of course take out the actual filters, and just have it as a way to pull oil out of the tank and pour it through the air back into the tank.

This puppy is on sale for $29 bucks and can turn over 350 GPH of water (probably less for oil)
http://www.amazon.com/Marineland-Penguin-Power-Filter-70-Gallon/dp/B0009IMDQM/ref=pd_bxgy_petsupplies_img_b

Don't forget to decorate your tank:

Sounds good.  Also if you wanted an added layer of security you could rig a temperature switch to the power for the rigs.  If temp in pond got above say 40C it would kill power to rigs.

Im not worried about that in the least. Temperature difference between bottom (where I pump most of the water) and top of the  pond can be 5-10C difference just from the sun. Between morning and afternoon you can add another 5+C to that when my filters are running. Fish dont mind. They will just swim where they feel most confortable, and if anything, Koi like warmer water than what I can offer them. They thrive when the water is ~30-35C, Ill never get there, except for some weeks per year at the top of the pond...

Once best avoids sudden temperature shocks, like from a hot bassin to a cool pond without some acclimatisation time, but intra day variance is not an issue. They are river carp, its not like you will not find huge temperature differences in a fast flowing shallow river.

The water in wetsuit isn't used for insulation.  A dry suit (not a dry wetsuit but an actual drysuit) will always be superior but dry suits are expensive, complicated (the air compresses at depth), and require a lot of maintenance.  It is the neoprene which provides insulating properties.  Technically it is the air bubbles in the neoprene which provide the insulation (air is on the best low cost insulators, and water is one of the best low cost conductors).  This is why as you dive deeper a wet suits becomes less effective.  The water pressure compresses the bubbles in the neoprene reducing the insulating value.  You can partially compensate with thicker neoprene or use a dry suit.

The "wet" in a wet suit keeps it simple.  The suit doesn't need to be "perfect fit" just snug enough to minimize water exchange.  The water layer aids in comfort and since water is a conductor is spreads around any heat loss.  For most diving it is simply "good enough", however if you have ever had a wet suit which is torn you will quickly find out how bad of an insulator water is.


Yeah not sure how big the body of water would need to cushion the temp swings.   Since water is such a good conductor of heat what matters is how well the pond can "exhaust" the heat into the atmospshere.   I also have no idea how much of a temp swing the fish can tolerate.  

I guess one could get a ballpark figure by measuring the pond temp in summer at dawn and noon.  The rise in temp ~= thermal energy from sun.  Figure out solar insolation, and number of hours and you could turn that into wattage.  i.e. pond got x watts from the sun and the pond temp rose y.  That might give p4man at least the magnitude we are looking out.    With only a 5C rise in temp can the pond dissipate 100W, 1000W, 10,000W, etc?

I dont believe so. the pond is not that deep. Its bowl shaped, no deeper than 1m60. Half the pond (by surface) is less than waist deep.   Surface area is 60m2. Then there is the fact I have a DIY "trickle tower"/ proteine skimmer thats designed to  expose the water to air and *lots* of aeration in general (heavy duty air pump in the filters and in the pond).  When I turn on all my pumps on a cold autumn day, I can easily decrease the water temperature by several degrees in a single day, 2000W isnt going to offset that.  Im not sure 20Kw would.

Anyway, heating the pond is not the objective. Heating the water in the filters would be quite a useful by-product, particularly in spring, although Im not expecting much difference even there. Too much flow. One can do the math, the filter barrels excluding filter material are probably around 200L and I believe are turned around every 4 minutes. At 2000W that is  ~ +0.5C. Better than nothing, but not impressive.

Insulator was the wrong word, but now I need you to explain something. Would the layer of water trapped by a wetsuit be considered an insulator, or is the insulating going on in the neoprene? Wetsuit without that trapped layer doesn't do anything.

Fucking thermodynamics...how does it work?

My point was that dumping a constant 2000w into a body of water will heat it, and I am not sure ambient temperatures and airflow will be enough to 'exhaust' it, so to speak. Throw the sun into the mix and you are going to have some wild daily temperature swings to the detriment of the fishes health.

The water rose in temp because it was a good conductor and the air wasn't.  Thus the thermal energy gets "trapped" in the water and the temp rises.

Water is a horrible insulator.  As an example a warm jacket isn't what keeps you warm.  A warm jacket traps air which keeps you warm.  Now take same jacket and soak it (even in hot water), put it on and walk outside.  Brrr.  The water "shotcuts" any insulation allows a highly conductive path between your internal body heat and the very cold outside air.

2000w will more than likely impact 10,000 gallons, though it wholly depends a lot on surface area. I had a 4,500g outdoor reef running 2000 watts of inline heater and it would keep the tank at 76-78 even when it was ~50F ambient and was still kicking off. The reef was lit with LED so there was almost zero infrared contributing to that. Water is an incredibly good insulator.

Price mostly. And convenience. Equipping 6 or 10 cards with full covers for watercooling is expensive, and it could be hard to find covers for all my cards. Remember I run rat rigs thrown together with leftover parts and then I plug in whatever 58x0 card I can find cheaply. I have like no 2 identical cards, and thats only gonna get worse .


Some more googling suggested that too. Well, up to 5-7C delta. This is getting more and more exciting .


Heat exchangers require I pump water through them. Thats probably not a good idea, considering its pond water; its gonna clog sooner or later, even if I were to pump "clean" water from the end of the filter (and Id rather heat the beginning of the cycle to help the aerobic process).  My filters are connected with 130 mm pipes, that doesnt clog so easily . Moreover, it requires 2 pumps, one for the oil, one for the water. Thats 2 points of failure.

 Then there is also... price. A decent sized heat exchanger is not that cheap. I may not need a big one from an efficiency point of view, but Id need one that doesnt clog. Instead I could buy one, or heck, should it prove necessary or useful,  several oil coolers from a car junk yard for next to nothing, or even if you buy them new, something like this:
http://www.ebay.com/itm/UNIVERSAL-15ROW-10AN-TRANSMISSION-RADIATOR-TURBO-ENGINE-OIL-COOLER-ALUMINUM-BLUE-/160721146846?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item256bba13de

isnt gonna break the bank, and I cant see how that would not work when submerged in relatively fast flowing and air bubbling 20-25C water. Like you said, water is a much better heat conductor than air, if it can cool the oil by blowing air over it, its gonna work a hole lot better submerged - I think.

Anyway, Ill probably setup a small scale experiment next month with a single spare card (8800GT) to see what happens. Still have to figure out where to best buy some suitable oil, hoses,  think of a filtration system and come up with a layout thats not completely unworkable. Its not gonna be pretty with all the motherboards suspended inverted above an oil bath, but if it works,  who cares

Why not just use a traditional water cooling rig w/ a heat exchanger?
http://www.koolance.com/water-cooling/product_info.php?product_id=944

As far as what temps are GPUs.  In watercooling (and I would imagine oil cooling too) water is such a good heat conductor that everything in the loop is within 1 or 2 degrees of everything else.  So if the oil reaches equilibrium around 50C then the GPU would be 50C.

Another way to look at it in reverse.  Say you pond can dissipate more thermal energy than your rigs can produce.  The pond water is 25C.  In the heat exchanger above using 7 LPM pumps (and water) we can transfer ~1600W of thermal energy and keep delta T at <=6C.  This means the hot loop will be in equilibrium at ~ 31C.   

In air cooling the GPU core temp being higher than the exhaust air temp is merely an effect of the poor heat conductivity of air.  If you used enough air (say thousands of cfm of airflow) you could get the input, gpu core, and exhaust air to all be roughly the same.

Assumming you have a properly sized radiator even if you were air cooling the radiator you can keep the delta T <10 C.  With a liquid to liquid transfer you could have a much lower delta T.  <5C or even 2C is possible.

If the radiator will be submerged in water you likely will get better heat transfer with a heat exchanger.  Radiators are designed assuming they will be used to force air through fins to acheive heat transfer.  

How about a little love for "Bubbles"? From 1985.
http://en.wikipedia.org/wiki/Cray-2

Okay I did some research myself. Toxicity is not a problem with pure mineral oil. you can even drink the stuff.

As for capacity planning; Lets assume I only submerge my GPUs (thats what I plan, just place them inverted with extenders so only the gpu's "swim"), lets put it at 1000W worth of GPUs in a 100L tank.lets look at the heating of the oil. I found this:

http://make-biodiesel.org/Biodiesel-Chemistry/time-to-heat-oil.html

From the above link:
Time in hours = 0.5 X Number of Liters X Temperature rise in °C / by element wattage

Solving that for temperature rise:
Temperature rise per hour = 1000W / ( 0.5 * 100L) = 20C per hour or 0.333C per minute.

Thats considerably less than I would have thought.

Lets assume a hot summer day with 35C ambient air temperature and my pond water being at 25C.

assume the submerged radiator manages to cool the oil to 10C above water temp, so to 35C.
I want the oil in mining rig to remain below 50C. Thats a 15C difference
That means I have to turn over the 100L every 5 minutes. So Id need ~1200L/hour throughput.
Actually, the amount of oil used in the rig theoretically wouldnt matter here.

Anyway, some googling found me this:

http://www.ebay.com/itm/350GPH-DC12V-80C-Brushless-Magnetic-Oil-Water-Pump-/160560267427?pt=BI_Pumps&hash=item25622340a3

Pretty much spot on for the capacity I just calculated, although that probably means its not enough when you factor in pump head and the fact the stated throughput is probably for water, not oil.

Still, seems quite doable with all the above assumptions. Looks like all I need is a pump similar to that one, but probably 2x or so as powerful, some (car) oil radiator and some tubing. Most of the stuff seems fairly inexpensive. Oh and Id need a filter somehow, as there is no way to make this setup airtight if Im only going to submerge the GPUs.

Question that remains; with 50C oil temperature, what would my GPU temps be like? Although it is probably different, can anyone using watercooling shed some light on the relationship between water temperature and GPU temps?

Im actually reconsidering my position on this and looking into submerging my rigs for when summer comes.

Here is the thing, I have a large Koi pond (50K liter) next to the shed where I would want to put my miners this summer.  And it wouldnt hurt to warm the pond water during fall and winter, even if the effect will be minimal in the best case. Even with a perfect heat exchange, 2000W is going to do next to nothing to the overall water temperature in the pond, but raising the temperature in the filters is beneficial to the filtering process, every degree helps.

Ill have to expand the filtration system for the pond anyway and  I was considering putting a few large (1000L) settling tanks in the shed. By itself, I wouldnt have expected that to do much, if anything, unless perhaps if I created an air duct of sorts around the miners to concentrate the warm air, and blow that warm air through one of the (open) tanks; i already have a 160L/hour air pump, I could add another one for that purpose. It wouldnt be much of a settling tank anymore then, and I guess it wouldnt do too much to reduce ambient heat either. or?

I guess the more efficient thing to do is submerge my rigs in mineral oil, pump the oil through a radiator which is suspended in a settling tank or filter  tank (Im using 300 liter rain barrels for biofiltering, the filter has a pretty high volume, up to 25K liter per hour).

A few questions, not sure if anyone here can help me with

- how toxic is mineral oil? Or would vegetable oil be better here? I dont fancy the idea of a small leak killing all my fish. I remember reading that a cheap way to buy large quantities of oil for submerged cooling is buying them as... horse laxative. I cant imagine a horse laxative being excessively toxic... ?

- what kind of hoses does one need? Do you need a special kind of rubber or plastic for oil? From the shed to the filtering installation is a fair few meters

- any suggestions on oil filtering?

- does anyone have any idea of dimensioning this? I got no clue how big a pump (pressure and flow rate) or radiator I would need. If it helps, by then I plan on having ~2000W worth of mining gear. The pond water rarely gets over 25C and more typical is 20C  and the water in the filter would have no time to heat up significantly because of the high flow rate. I would *guess* keeping the oil below 35-40C would be good enough to keep the cards reasonably cool, although that is more guesswork on my part.

ANy thoughts or ideas on the matter would be appreciated.

+1, that's why servers tend to be so loud. They have specially designed airflow paths and extremely high velocity fans.
Water is useful only to keep the noise down.

Fair enough.