I was watching Gamers Nexus’ AIO video and one of the PCs I built has the AIO installed in a definitely sub optimal way. This led me to thinking about how to configure the AIO in an appropriate way.
So for the next days I thought about what the video said and how it applies to my situation. I came to the conclusion that one (very) specific portion of the video just didn’t made sense (to me). I therefore wrote an email to GN regarding this portion and how I had trouble understanding it/how it might be incorrect. They didn’t seem to be in the mood of arguing (which, to be fair, was also stated clearly in the reply to my second (and last) email)..
However, as I already have my arguments in written form I decided to post them here.
I would really like to know if my arguments hold up or what I am missing/misunderstanding:
For this whole post I am going to concentrate only on one specific radiator position/installation:
An AIO in the case “front mounted and with the tubes down”.
The specific part begins at time stamp 19:44 (https://youtu.be/BbGomv195sk?t=1184):
Finally when front mounted and with the tubes down this air
bubble issue is no longer a problem.
Ideally the pump is still below the top of the loop, because
the other tank should now be at the top of the loop.
If that’s the case we don’t need to worry about air accumulating in the pump,
because it won’t,
What I am searching for is the explanation that is missing here (well, technically there is an explanation: “because it won’t”).
It continues with:
and we also don’t need to worry about it getting pulled through the barbs,
because that’s not where the air is anymore it’s now at the top tank
that is not connected to them.
[…]
There’s one huge reminder for this orientation though:
do not mount the pump in such a way that it is on the top of the loop
with the barbs at the bottom.
Because then it hasn’t fixed anything.
If you intentionally position your radiator lower on the front panel
[…] rather than higher it is possible that the pump ends up at the top of the loop
at which point we’re dealing with all the same concerns
as showed earlier when the pump was located at the top.
This is the part were I do not understand how they got to this conclusion.
I believe that his reasoning is: “Air always finds the very top of the loop”.
After spending a considerable amount of time thinking about it I came to an opposite conclusion:
That having the pump higher than the top of the radiator is perfectly fine.
To explain my reasoning I give the following scenario:
BEGIN SCENARIO
Air in a closed loop is NOT able to move to the highest point in the loop!
This is not an assumption; also see: the Wikipedia page “Air lock”: https://en.wikipedia.org/wiki/Air_lock :
The gas, being less dense than the liquid, rises to ANY high points.
The air trapped inside the loop is not going to find the highest point in the loop.
All that matters is: there is a low section (completely filled with water) and multiple higher sections where air can be trapped.
The important detail is that the relative maximum height of the higher sections does not matter: air gets trapped regardless.
When looking at an AIO in the case “front mounted and with the tubes down”: there is a low section, where the tubes of the pump enter the radiator, filled with water. And there are two higher sections the top of the radiator and the pump, in BOTH of which the air is going to be trapped.
The point I am trying to make now is that the exact height of the radiator or the position of the pump does not matter!
The physics (of trapped air) is exactly the same for:
- The pump is higher than the top of the radiator
- The top of the radiator is above the pump
END SCENARIO
Based on the ideas of the scenario the following contradiction contained in the video develops:
They recommend that the pump can be higher than the (water filled) tubes, but do not recommend installing the pump higher than the top of the radiator.
However, if we look at the scenario and we know that installing the pump higher than the tubes is (at all) OK, then the implication is: “the pump can be mounted even higher than the top of the radiator”.
Again in different words:
Looking at the scenario, it does NOT make sense to say:
Air is ONLY going to be trapped in the radiator if the pump is mounted lower than the top of the radiator.
<=> Air is not going to be trapped in the pump if the pump is mounted lower than the top of the radiator.
<=> How it is described in the video
In fact experience/observation with “Air Locks” tells us: air is always going to be trapped in all highest sections (therefore in the radiator AND the pump).
So the question now is: “How does the pump get rid of trapped air?”
My hypothesis is: “The pump intake is ~100% water -> Air bubbles residing at the pump are getting swept away!”
In their video they seem to be arguing similarly:
[…] we also don’t need to worry about it getting pulled through the barbs,
because that’s not where the air is anymore it’s now at the top tank
that is not connected to them.
The Wikipedia article about “Air lock” states:
Flushing the system with high flow or pressures can help move the gas away
from the highest point […]
Based on the given information I would argue that the pumps should be able to getting the air bubbles swept away easily.
A relevant next experiment could be: “How strong (or how much time) does the pump need to be to get rid of trapped air?”
Regarding the outcome of this experiment: I would claim the mounting height is going to be negligible in all reasonable cases. (If somebody is curious about why I think this is the case; please ask. This post is already pretty long )
So, again, the conclusion I decided on is:
Installing the pump higher than the top of the radiator is perfectly fine. Again for: An AIO in the case “front mounted and with the tubes down”
And:
I would really like to know if my arguments hold up or what knowledge I am missing/misunderstanding