I think you are worrying to much about the heat. You realize that 70F is only 21C. Here in Texas last summer I was running a bunch of GPU miners. They run at 70C which is 158F. The hot Texas summer day of 115F (46.1) air was enough to cool the miners down.
This year I have a bunch of S1 Antminers and we have already had high 95+F days so far. The S1's did fine with just some outside air being blown into the room with the miners and the hot air leaving the room. In the main mining room with the building closed up, the room was at 115F (46.1C). I opened the doors and windows to get the air circulating and the room dropped to near outside ambient temp in no time.
I don't see that much of a problem here when it gets to summer temps at 115F (46.1C), just keep the air moving with outside air and have several replacement miner fans on hand as fans fail when you don't want them to. If you cannot create the air exchange from outside with the inside, then you need to rethink you setup. You need air flow from outside to inside to outside.
This reminds me of the late 80's and early 90's when small and medium businesses where having their computers networked. I could not count how many times I was called in to troubleshoot network problems only to find a server or router closet. That was the dumbest idea I seen done over and over by inexperienced so called "tech's". Putting electronic equipment that produces heat into a closed off, normally not air cooled, closet. You have to have air exchanging to keep the equipment running. Same with the miners.
This year I have a bunch of S1 Antminers and we have already had high 95+F days so far. The S1's did fine with just some outside air being blown into the room with the miners and the hot air leaving the room. In the main mining room with the building closed up, the room was at 115F (46.1C). I opened the doors and windows to get the air circulating and the room dropped to near outside ambient temp in no time.
I don't see that much of a problem here when it gets to summer temps at 115F (46.1C), just keep the air moving with outside air and have several replacement miner fans on hand as fans fail when you don't want them to. If you cannot create the air exchange from outside with the inside, then you need to rethink you setup. You need air flow from outside to inside to outside.
This reminds me of the late 80's and early 90's when small and medium businesses where having their computers networked. I could not count how many times I was called in to troubleshoot network problems only to find a server or router closet. That was the dumbest idea I seen done over and over by inexperienced so called "tech's". Putting electronic equipment that produces heat into a closed off, normally not air cooled, closet. You have to have air exchanging to keep the equipment running. Same with the miners.
Yes, 70F outside is far from a crisis for the miners, it's just a harbinger of what is to come. Perhaps you like your house at 85 to 95F; I, and especially my wife, do not. We are Minnesotans. We are used to temps of 10F outside, not 100F.
I keep my miners in the garage. The garage doesn't have any windows. I prefer not to advertise the fact that I have lots of nice electronics in there. With the door closed and it's upwards of 70F outside, my miners (Ten S1s and six Cubes) bring the garage to 85F in under a half hour and the miners' temp sensors quickly head north of 75C. The cubes drop 10GH apiece at the high clock rate. They don't have temp gauges that I can see via the web interface. When the Cubes go over whatever is their maximum temp, they drop down to the low clock rate. The error rate of the S1s increases from under 100 per hour to several ten thousand per hour. The number of invalid/discarded/rejected shares jumps from tens to tens of thousands. Then the chips on all the miners randomly start getting flagged with X's a few at a time. So no, the miners are not happy at 50C or higher ambient temps. When it hits 80F and 90F outside, forget it, the garage turns into an oven.
Secondly, I doubt your miners are doing "just fine." I'd be interested what temp the S1s are reporting on their miner status web page. If the room is already 50+C, I'd bet they are running at 70 to 80+C. At those temps you can look forward to cumulatively degrading hashing rates and/or chips failing. Me, being an electrical design engineer, I want my miners to perform as best they can for as long as they can. Right now, when they are operating below 50C, they get hashing rates around 220GH consistently, with no permanent X's on any chips.
Lastly, again, being an electronics design engineer, I tend to be a little anal about keeping my electronics running in the "low to mid" temp range stated on a devices data sheet, if I can, and stay far away from the "absolute maximum" temp range.
So, all those who like to bake their miners and shorten their useful life, you can line up with AbiTxGroup.
I'll keep it cool thank you.
It's also about airflow, not just temps. In many ways, 20k CFM of -10 degree air = 10k CFM of -20 degree air. Cut a hole and mount an exhaust fan high up in your garage. Cut another one and mount an intake fan low on the far side (north/shaded side is best for intake). With the right capacity fans, you can make it so that your garage never rises more than a couple degrees above the exterior temps. This will be much cheaper and less trouble-prone than your proposed water-cooling design.
Speaking of which, the "thermal mass" of a 340Gal tank isn't going to do jack. (Although of course it's a good idea to have a reservoir in case something goes wrong with your plumbing.) If you've got cool water coming in from your tap, running through your system, and then running down the drain, the system is going to use so many GPM of cool water regardless of whether it's initially stored in a tank.
The stagnant air in your garage hits 85F in half an hour, with exterior temps of 70F. Your miners are putting X BTU's into the garage at a constant rate. The rate of heat exchange is related to the temperature differential. At 15F differential, there is enough heat exchange going on between the garage and the exterior to maintain equilibrium.
This is how all cooling systems work. All you're doing is moving heat from one place to another via a medium. The "thermal mass" of the medium of heat exchange doesn't matter. What matters is the overall heat exchange rate.
The amount of water stored in my car's cooling system doesn't make a difference. Once it hits the minimum level required to fill the radiator, engine block, and all connecting lines, having an extra gallon or two in there won't make a difference. (It will take a bit longer to reach equilibrium temps from a cold start, but other than that, no difference.) What WILL make a difference is if my water pump goes out and the flow of water through the engine stops. In that case, it won't matter how many gallons of coolant I have in my reservoir; the engine will overheat. Same with the radiator being blocked. If air is not flowing over the radiator at a sufficient rate, the engine will overheat. (Dependent upon the air temps, of course -- I know you northerners sometimes block your radiators with cardboard in the winter when the temps hit the negatives. In this case, there is sufficient heat exchange even without any airflow, due to extreme temperature differential.)
I apologize for the continued derailment of the thread.
I'll keep the reply shorter this time. You have a substantial misunderstanding of the system I am designing and using.
I am currently using this method of water cooling. It works as designed. NO airflow AT ALL is required. NO garage modifications are required, short of adding some plumbing. The heat is transferred to the water by waterblocks. The heated water is then returned to the tank. When the water in the tank is too hot to keep the miners at optimal temperature, the hot water is DISPOSED down a drain. The heat leaves with the water.
The purpose of the thermal mass water tank is to recirculate the water until it reaches the temperature where disposal is warranted. The disposed water is replaced by fresh cold water from the water main at a much slower rate due to recirculation of the tank of water. This is not a closed system like a cars water cooling system which has to dispose of the heat to the air.
When I was running the miners with just fans, I just opened the bottom of the garage door to exchange air. That worked fine, but I know worse is coming. That was when I started designing this water cooling system. The garage only heated up so severely when the garage was closed up AND the miners are running with fans only. That is not the way I run the miners. It was an experiment to see how fast the heat accumulated.
The 70F degree air outside right now is NOT the concern. It is the 85+F temps that are coming that are the problem. When starting with such temps no amount of air exchange between indoors and outdoors will cool the miners below the ambient temperature. In fact, considering the 570+ watts of heat dissipation by the miners, the chips have little chance to get below 70C (158F). As I noted above, I have observed significant performance degradation, malfunctions and even chip failures begin when the S1 web interface is reporting temps of 60C (140F) or higher.
End of thread derailment.
Everyone here knows how water cooling systems work. Please get a blog for this stuff - or visit the hardware topics...
