Pressure in resevoir

[Eddie Current]

If our systems act like any other cooling system and the coolant heats (expands) and cools (contracts), than I would think that having a pinch of vacuum on the system would be a plus. Think of it like this, when you top off your system when it cold and there is little room for expansion when heated it is now under pressure. If the system was under a pinch of vacuum when cold, when it heated up it might be in a neutral state.

Just thinking out loud here. And my pinch might be a little more than yours

 

[S_I_N]

Big difference in the heat from an engine to the heat produced by s computer. There is a slight level difference between running and off but if it goes a couple inches from off to on then there's air trapped somewhere. Your not going the see a big compaction of inches in a Rez in this small of volume

 

[Eddie Current]

Its all relative.

 

[EarthDog]

Yes and no...

Temperature differences here are AT MOST 20C in a loop with enough rads and fans. A cars' difference is like 70c. So while it is all relative, pinching the tube until it's shut even (really eddie, it's not in how hard you pinch it...) that still won't do anything. Try it when you get your system.

Top off as needed people...

 

[Eddie Current]

Try it when you get your system.

When I find my big syringe I will be doing so in my current system as I think I would rather see my system in a slight vacuum or in a natural state than under pressure when hot. Again in my opinion, if your going to have a leak its going to be when the system pressures up and this might be one way to keep that from happening even in the slightest. Free insurance I say!

---Edit--

Why do people always relate the expansion and contraction of a fluid to an automobile?

 

[S_I_N]

because in our setups its almost like an automotive setup. you have a res rad and block in each type. But in our pc's the temps never reach what automotive systems do. Ic auto's the temperature far exceed what todays computers put out so yes you will have pressure build up. You need high heat to get that kind of pressure to build. Water does not really contract and expand at the temps our pc's run at. So seeing a big rise and fall in our res's is simply due to air being trapped somewhere, it can get in the hardest of spots to get out, thats why its recommended to tilt/rock/shake it about while bleeding to aide in the dislodging of said air. I have been doing alternate cooling of one form or another since the mid 90's everything from water to tec cooling all the way to super chilled to phase change cooling. While I do not profess to be the expert in all. I have enough experience in it to know what the system can do and will do once its up and bled properly.

 

[EarthDog]

Exactly. There really isn't much pressure there due to temperatures and the expansion of the water. Test it, do what you would like, but it is an exercise in futility, because, well, science.

 

[Eddie Current]

Water does not really contract and expand at the temps our pc's run at.

Exactly. ...science.

I don't know what SIN is trying to say but it's not science. Let take the PC out of the equation, it doesn't matter how many water molecules you have .5 liters or .5 gallons when you heat them up they will expand (that's a know fact proven by science).

I'll repeat what I said before "this is my opinion" and the last word I will waste on this subject.

 

[Conumdrum]

Thank you for not using science and realizing resistance is futile. Unless we are talking about the flow in an exhaust vent in a Death Star long ago.

If you increase the temp of a liter of water 15C above ambient how much does it's volume expand? Science says a very very little bit. So little it's ... someone, find the formula please so we can science more.

 

[EarthDog]

(that's a know fact proven by science).

Indeed. Here it is.

We are using the coefficient of thermal expansion of water = 0.00021 (1/oC)

1 deg C rise in the water tank = 1.0002 Unit Volume Rise

or if our water container is closed, such as a water heater tank, we should be able to say

1 deg C rise in the water tank = 1.0002 Unit Water Pressure Rise

.....

Effects on Water Pressure of Heating Up Water in a Tank

....if we heat one volumetric unit (say one cubic meter, one gallon, or whatever) of water from 4 °C up to 80 °C (that's a 76 °C rise), the new water volume (in an open container) will be 1.016 x the original volume, or the pressure (in a closed container) will be 1.016 x the original pressure [since the volume could not expand the pressure must increase instead].

http://inspectapedia.com/plumbing/Hot_Water_Expansion.php

So if that is an 76C difference... that means its 4x less all around on a 19C difference, right (which is a terribly underadded loop if you are getting that big of a difference)?

Perhaps this puts things in perspective as far as how little the difference actually is within a water cooling loop.

 

[S_I_N]

I don't know what SIN is trying to say but it's not science. Let take the PC out of the equation, it doesn't matter how many water molecules you have .5 liters or .5 gallons when you heat them up they will expand (that's a know fact proven by science).

I'll repeat what I said before "this is my opinion" and the last word I will waste on this subject.

we all understand its your opinion and we are trying to explain to you why you may of been misguided in your opinion.
Yes water expands when heated we all agree on that.
Yes it takes alot of heat to get water to expand.
Yes in an open container the level will rise.
Yes in a sealed container it will produce pressure.
No in a close looped setup IN A PC WHICH THIS THREAD IS ABOUT it will not expand enough to create any appreciable pressure or level change in a res, simply because the temps do not get hot enough for that to happen.

By ED's example say your volume is at 1 inch on a ruler when heated 76c hotter it will rise (in an open container) to 1.016 inches hardly noticeable at all. So for a level in a seal or open pc system to raise or lower any significant amount there must be air somewhere that is compressing when the pump turns on. Because air will compress under these conditions. Once all the air is out its barely noticeable (the level in the res) pump on or off.

let me further say that in this case (OP's post) I'll wager that if he ran his pump without the comp on (meaning no heat source to warm the water) his levels will still fluctuate as it was/is when running the computer. This is simply a case of bleeding and air getting trapped not heat causing the levels to rise.

*steps off soapbox*

 

[EarthDog]

I now know why your forums have fewer visitors than others. You guys need to tone down the hate, negativity and closed mindedness a little (in my personal opinion).

eddie,

I'd say you have received A LOT of quality, FREE, advice from the members of this forum. There is a very knowledgeable group here that shared what we know, and in this case, the science behind it. Of course you are welcome to still try it.

Anyway, I'd chill out on insulting the forum that helped get you as far as you are are...I cleaned up the unnecessary posts.

 

[S_I_N]

I must of missed what he was referring to. But if you felt my reply was hateful negative or closed minded then I sincerely apologize as that's not how it was intended. It was merely an attempt to help out those reading

 

[Mr.Scott]

Anyway, I'd chill out on insulting the forum that helped get you as far as you are are...I cleaned up the unnecessary posts.

No, it was necessary, but thanks anyways Joe. I owe you.

 

[GTXJackBauer]

Well, I'll be damned. I must've missed the festivus festivities. Dam Insomia Seaon!