Air makes its way from the reservoir into the radiator.

[Waldorf]

@Vya Domus
no need for that just add a res, maybe even mount the pump to that.

def install this.

valve

 

[BoggledBeagle]

I thought it is better to have a loop sealed to prevent losing coolant due to evaporation.

The air in the reservoir (that is an expansion tank) provides a relief for water expansion, which is necessary, because water is very incompresible and even a small difference in temperature leads to a huge pressure buildup without any air in the loop. According to this:

On the topic of thermal expansion and filling loops to the brim : r/watercooling (reddit.com)

the pressure buildup in a loop without any air in it (and perfectly rigid tubes, etc) warmed up by only 5°C would lead to 33 bar pressure, which would explode or least compromise any loop. The guy recommends at least 20 ml of air in the reservoir per liter of water (without any reasoning or calculation).

 

[Vya Domus]

Went on with my test, when I unscrewed the cap after I let the loop heat up the change in pressure caused a couple of air bubbles to show up and after it cooled down I noticed a couple of more air bubbles in the reservoir maybe this will do something after all.

There's a fair bit of pressure that builds up once the loop is heated, there was an audible fizzle when I took the cap off, it seems pretty airtight in there.

 

[ir_cow]

Yeah without a rez, you are bound to have a lot harder time getting all the bubbles out quickly.

Unscrew. Fill. Run and move the case around. Repeat for a few days until all air is gone.

 

[A Computer Guy]

Yeah without a rez, you are bound to have a lot harder time getting all the bubbles out quickly.

Unscrew. Fill. Run and move the case around. Repeat for a few days until all air is gone.

Just to be clear don't run around with your case because that's how accidents happen.

 

[OkieDan]

3) Let me math this out for you...using easy numbers. CPU generates 200 Watts and GPU creates 400 watts. Theoretically at stable state you get 600 Watts into loop and 600 watts out of loop...but the problem with both heat sources next to one another the fluid temperature has to rise much higher to support that. The counter is that...because of numbers you don't see it. To raise one liter of water one degree C you need 4180 Joules...1 watt = 1 Joule/Second, so to raise a fluid loop 1 Liter/minute flow you'd need to dump 4180/60 = 69.67 Watts of heat into the system. Yep, that 600 Watt heat source should only have you increasing 8.6 degrees C with a liter per minute flow (and no radiator). Hopefully it's easy to see then that 1500 liters/hour, or 25 liters per minute (25 times faster than our calculation, for a D5 pump) basically yields such low fluid temperatures as to be silly. Yes, that 600 Watt thermal load at a D5 pump rate of 25 Liters per minute, would amount to a fluid temperature of 0.344 C assuming there was no radiator to release energy from the system. Throw in the assumption of radiators existing...and you being at thermal equilibrium, and you've got that 1 liter of fluid heating up with 600 Watts, flowing into a radiator, cooling down 600 Watts, and zero net temperature change in the loop.

4) Does the math make sense?

I don't think dividing 4180 by 60 makes sense. 600 Watts for 6.67 seconds would be 4180 joules, thus 1C rise every (6.67 x liters) seconds.

Also, why would pump speed affect this the way you stated? The total water capacity would make the water temp rise at a different rate but capacity doesn't increase with pump flow. You obviously need to have circulation and faster flow will result in better heat transfer from CPU to liquid but won't count towards capacity like you seemed to indicate.

 

[Steevo]

I thought it is better to have a loop sealed to prevent losing coolant due to evaporation.

The air in the reservoir (that is an expansion tank) provides a relief for water expansion, which is necessary, because water is very incompresible and even a small difference in temperature leads to a huge pressure buildup without any air in the loop. According to this:

On the topic of thermal expansion and filling loops to the brim : r/watercooling (reddit.com)

the pressure buildup in a loop without any air in it (and perfectly rigid tubes, etc) warmed up by only 5°C would lead to 33 bar pressure, which would explode or least compromise any loop. The guy recommends at least 20 ml of air in the reservoir per liter of water (without any reasoning or calculation).

I will bite. Only cause I have had a sealed loop for over 10 years.

That doesn't account for components expanding with heat, water will evaporate through plastic tubing, and air isn't necessary, in fact it's oxygen doesn't play nice with components, but you can add or use additives to prevent the issue. I have had air in my loop, and at a high enough flow rate it made crap all of cooling difference (it was foam essentially, but still 99% liquid)

 

[Waldorf]

@BoggledBeagle/Steevo
just do a quick web search about ppl's loop leaking or even "exploding" because of it being sealed, even if the res has some air in it.

a while back i had to drain/clean the new Eisbaer AIO from a friend because of tiny metal pieces collecting in the res (i assumed from manufacturing), and didnt care for return to A or wait for RMA with Alphacool.
not having any pre-mixed coolant, decide to fill with distilled water and use dead water additive (i still had). and while it worked for about a few hours (wanted to flush out any shavings left/original coolant),
at the time i was going to drain and refill again, galvanic reaction between the dead water additive and the metals had increased pressure to the point where the refill cap flew off when unscrewing.

and having seen that some of the G1/4 parts, that i wanted to use for converting my 280 AIO (to loop), had improperly applied "coatings/paint", leaving areas with bare metal.
so this can easily happen with a complete custom loop as well, if using biocides and distilled (or worse deionized) water, and using mixed metal parts..

 

[BoggledBeagle]

decided to fill with distilled water and use dead water additive (i still had). and while it worked for about a few hours (wanted to flush out any shavings left/original coolant),
at the time i was going to drain and refill again, galvanic reaction between the dead water additive and the metals had increased pressure to the point where the refill cap flew off when unscrewing.

What is that?

 

[Waldorf]

a biocide (sold by FrozenCpu in the U.S.)
basically a liquid form of silver coil, so you dont have any bio growth because of the "warm" water in a LC.

its fine to use and tends to give some of the lowest temps when used with distilled water (never use deionized water) compared to pre-mixed stuff,
but it reduces ph (can make coolant too acidic) and mixing it with other coolants produces gunk, and the tiniest bit of exposed metal can be cause for galvanic reaction,
increasing pressure (gasses) that can lead to leaks/failure, or at least gunk up your blocks pretty quickly..

since most of the connectors i purchased were not properly coated on the inside, i decide to get premixed coolant (wanted opaque look anyway),
instead of wasting time with return, and possibly risc the same problem again.

 

[BoggledBeagle]

Are they still selling it? I cannot find it in their shop. Seeing what you wrote about it, it is probably a good idea not to sell it.

 

[maxfly]

Are they still selling it? I cannot find it in their shop. Seeing what you wrote about it, it is probably a good idea not to sell it.

I doubt FrozenCpu would have it. They had a going out of business sale last year and cleared out all of their stock. They've only recently reopened in like the last 3-4 months iirc. But I'm pretty sure that stuff hasn't been available for several years.