Do High Coolant Temps cause Leakage?

Zarathustra[H]

Zarathustra[H]

Extremely [H]
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Hey all,

I popped open my case today to clean out some dust. When I did I noticed some evidence of dried coolant on the back plate on my GPU (right below the CPU block), and on top of my PSU (right below the GPU fittings). The spots were completely dry, but shiny and colored from the coloring and additives in the coolant, so whenever it leaked it was not very recent.

I wiped up the dried coolant, and put paper towels underneath, and have been testing under full load all day today, with not as much as a drop coming out of those fittings. I simply cannot reproduce the leak.

Then it struck me. I remembered this one night I started a gaming session, and accidentally left my fans off. It wasn't until quite a while of poor framerates I finally realized it had been throttling due to overheating. The coolant temp levels probably went well in excess of what is safe for the pump. Luckily the pump does not seem to have sustained damage.

This has me wondering. Could the thermal expansion effects of heat have caused my fittings to leak during that episode, and now that the coolant temps are normal again (usually about 35C under high load when the room is not airconditioned at about 85F) the leaks are gone?

If not, I can't explain it. Appreciate any thoughts.
 
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So, Tubing becomes REALLY SOFT at high temperatures. So much so that a tube that is ROCK SOLID at room temp, we're talking "Lift the entire PC by using this tube as a handle" solid, can easily pop out with slight tension when at 60+ degrees (Celsius).

Not saying that is what's going on now, but it certainly could be.
 
KazeoHin said:
So, Tubing becomes REALLY SOFT at high temperatures. So much so that a tube that is ROCK SOLID at room temp, we're talking "Lift the entire PC by using this tube as a handle" solid, can easily pop out with slight tension when at 60+ degrees (Celsius).

Not saying that is what's going on now, but it certainly could be.
Click to expand...

Sounds at least plausible then. I heated up the tube, and while it was hot, the seals around the fittings had a slow leak, but now that they are back down at sane temperatures, I can't reproduce the leak.
 
Zarathustra[H] said:
Sounds at least plausible then. I heated up the tube, and while it was hot, the seals around the fittings had a slow leak, but now that they are back down at sane temperatures, I can't reproduce the leak.
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I know it sounds whacky, but it's possible the pump-speed may be the culprit as well. High tubing flexibility + High fluid pressure may be the mix perfect for a slight leak. If may be that you've adjusted the pump speed downward after the leak happened, but before you noticed it, OR its a PWM pump that adjusts it's speed automatically thus it is REALLY hard to recreate the exact conditions to reproduce the leak, OR OR it's an incredibly slow leak, causing maybe a drop or two after HOURS of extended heat.

I've seen some situations like this, check to see if you have any particular tubes at tight bends near or above the scene of the crime. I found out the hard way that some tube bends that are fit as a fiddle when cold can EASILY pop out when warmed up, and that 90 degree fittings are your friends in that situation.
 
high temps cause the fluid to expand so if there is nowhere for it to go, like the res is full and sealed, then it could push past O-rings. it could also be the tubing getting soft/deformed as mentioned ^.
 
pendragon1 said:
high temps cause the fluid to expand so if there is nowhere for it to go, like the res is full and sealed, then it could push past O-rings. it could also be the tubing getting soft/deformed as mentioned ^.
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This. Particularly if you are rocking rigid tubing. Flexxy tubing has a bit of give when it warms up that rigid tube doesn't. It is always smarter to leave just a bit of an air bubble in your reservoir so that expansion/contraction compresses air rather than your fittings.
 
pendragon1 said:
high temps cause the fluid to expand so if there is nowhere for it to go, like the res is full and sealed, then it could push past O-rings. it could also be the tubing getting soft/deformed as mentioned ^.
Click to expand...

Probably a combination of all of this. High pressure due to high temperature caused leakage around soft tubing. Pressure lowered after cooling down, causing a vaccuum. If the reservoir hasn't been opened, it's possible that vaccuum still exists and is preventing things from leaking when warmed up.
 
After filling and bleeding, I will typically thermally punish my system with the reservoir uncapped, getting the coolant temp 5°c over where it usually runs, and then capping the system while it's hot. This means that once it cools down I'm running under a slight vacuum, but that is preferable to the alternative!
 
I'd also argue that air trapped in your loop will expand far more with temperature than water will, so my guess is that a large quantity of air in your res will contribute to the pressure problem more than alleviate it.
 
VanGoghComplex said:
I'd also argue that air trapped in your loop will expand far more with temperature than water will, so my guess is that a large quantity of air in your res will contribute to the pressure problem more than alleviate it.
Click to expand...

Well, to me the solution is to not be an idiot and forget the fans off again.

When I first built the system I hooked up loop temp sensors to a fan controller and used it to control fan speed.

The problem with this is that it would just soon up the fans on hot days, and down on cold days which was annoying.

Using the motherboard CPU fan header wasn't very good either, as that didn't set fan speed based on CPU load only, not based on GPU load, and, if ifdle for a long time it would let the coolant get hot, such that when the CPU loaded up, the fans couödnt cool the coolant down enough to keep the CPU cool, leasing to a temp spike before reaching a stable temp at load.

In the end I just gave up on any assemblance on automated control and just soldered my own manual dial PWM controller board and manually set the fan speed.

Fans at ~480rpm are perfect for idle and light desktop use. Heavy games on a warm day can require fans at 1,250rpm and sometimes higher to keep the GPU at 40C or below.

It geberally works pretry well, espexialy since I have a large volune loop with large res, so the loop temp changes slowly, and I have plenty of time to adjust if I need to. The problem is that this one time I just forgot. Oops.

I should put a beeping alarm on there that goes off if the loop temp exceeds like 40-45C. That way I won't pull a stupid again :p
 
Zarathustra[H] said:
Well, to me the solution is to not be an idiot and forget the fans off again.

When I first built the system I hooked up loop temp sensors to a fan controller and used it to control fan speed.

The problem with this is that it would just soon up the fans on hot days, and down on cold days which was annoying.

Using the motherboard CPU fan header wasn't very good either, as that didn't set fan speed based on CPU load only, not based on GPU load, and, if ifdle for a long time it would let the coolant get hot, such that when the CPU loaded up, the fans couödnt cool the coolant down enough to keep the CPU cool, leasing to a temp spike before reaching a stable temp at load.

In the end I just gave up on any assemblance on automated control and just soldered my own manual dial PWM controller board and manually set the fan speed.

Fans at ~480rpm are perfect for idle and light desktop use. Heavy games on a warm day can require fans at 1,250rpm and sometimes higher to keep the GPU at 40C or below.

It geberally works pretry well, espexialy since I have a large volune loop with large res, so the loop temp changes slowly, and I have plenty of time to adjust if I need to. The problem is that this one time I just forgot. Oops.

I should put a beeping alarm on there that goes off if the loop temp exceeds like 40-45C. That way I won't pull a stupid again :p
Click to expand...
I believe that you should buy an Aquaero.

Of course, I believe that everyone with a watercooled system should buy an Aquaero, so take that for what it's worth. XD
 
Zarathustra[H] said:
I should put a beeping alarm on there that goes off if the loop temp exceeds like 40-45C. That way I won't pull a stupid again :p
Click to expand...

Beeping alarm should do it -- if you're lucky, your BIOS has a temperature alarm, and you just need to configure it.
 
toast0 said:
Beeping alarm should do it -- if you're lucky, your BIOS has a temperature alarm, and you just need to configure it.
Click to expand...


Sadly, my motherboard does not have a connector for temperature probes.

I could go by CPU temp, but that may not catch it if the major heat source is the GPU, and the CPU has low load.

I did buy this little dedicated thermal control board which might do the trick though.
 
VanGoghComplex said:
I believe that you should buy an Aquaero.

Of course, I believe that everyone with a watercooled system should buy an Aquaero, so take that for what it's worth. XD
Click to expand...

I've always been interested in the Aquaero, but the last time I researched it there were so many different modules and configurations, most of them only on webpages in German (my German is very rusty) that I got confused and delayed shopping for one.

That, and I also remember them being excessively expensive.
 
Zarathustra[H] said:
I've always been interested in the Aquaero, but the last time I researched it there were so many different modules and configurations, most of them only on webpages in German (my German is very rusty) that I got confused and delayed shopping for one.

That, and I also remember them being excessively expensive.
Click to expand...
They're pricey, but most of the price is the screen, the regular versions all come with one.

http://www.performance-pcs.com/aquacomputer-aquaero-6-lt-usb-fan-controller-26462.html

Dis right here is the one you want. No frills, just awesome standalone configurable cooling goodness.

PM me if you have any questions - I absolutely love mine. It'll treat you right.
 
Zarathustra[H] said:
Hmm.

But this one is just a board?

I thought they were 5.25" bay mounted with screens?
Click to expand...
The "flagship" is 5.25" with a screen, yes, but frankly, the power of these units lies in the software. I don't see a purpose to the screen other than eye candy. After using the software I couldn't imagine the depth of configuration possible being available on a little LCD with a few buttons.

The board is nice because you can pop four holes and mount it wherever is convenient for your cable runs. You don't have to see it - you don't even have to run the software anymore once you've set it up, because once it's configured the thing runs standalone, executing your configuration by itself.
 
VanGoghComplex said:
The "flagship" is 5.25" with a screen, yes, but frankly, the power of these units lies in the software. I don't see a purpose to the screen other than eye candy. After using the software I couldn't imagine the depth of configuration possible being available on a little LCD with a few buttons.

The board is nice because you can pop four holes and mount it wherever is convenient for your cable runs. You don't have to see it - you don't even have to run the software anymore once you've set it up, because once it's configured the thing runs standalone, executing your configuration by itself.
Click to expand...


Hmm.

The software appears to be windows only.

If I configure the unit using the software, does it need to be running, or if I reboot into Linux would the settings remain and still be active?
 
Zarathustra[H] said:
Hmm.

The software appears to be windows only.

If I configure the unit using the software, does it need to be running, or if I reboot into Linux would the settings remain and still be active?
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You don't need to be running the software for the unit to work. Your configuration is stored in memory on the board, so it can run completely independent of your OS.

I can't say for sure if the board will have access to embedded temperature sensors in your hardware if it's running without the software. Personally that's a non-issue, because the only temperatures my Aquaero control on are the ambient air and the coolant temperature (or more specifically, the delta between those two), which it gathers via dedicated sensors plugged into the board itself.

The only link my unit has to the rest of the system is a fake "tach" signal that it generates for the motherboard's CPU_FAN header. That tach signal will halt if my pump stops working or if the coolant temperature gets too high. Along with the tach stopping, an audible signal sounds from the unit: all this stuff was configured by me in the software.
 
I would think seepage around fittings would be pressure related? I don't see how high temps could cause that, but stranger things have happened.
 
IdentityCrisis said:
I would think seepage around fittings would be pressure related? I don't see how high temps could cause that, but stranger things have happened.
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Well, 2+ weeks later at normal temps, and I have not been able to reproduce any dripping.

There are multiple ways tempersture could cause leaking.

1.) Heat causes the tubing to soften and softer tubes are more likely to give.

2.) Thermal expansion and contraction. As materials heat up they expand. Different materials expand at different rates. Generally metals expand more than other materials. So, if the loop gets really hot, the metals in the fittings could expand just a tiny bit more than the rubber seals/tubing resulting in a leak.

I'm leaning towards the latter being the case in my system, as it has stopped since cooling down. This would be expected behavior for thermal expansion/contraction.

If the soft tubing were the cause, I'd imagine the leak would be permanent. The tube could loosen in the fitting while soft, and not go back again when it hardened up.
 
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Zarathustra[H] said:
Well, 2+ weeks later at normal temps, and I have not been able to reproduce any dripping.

There are multiple ways tempersturw could cause leaking.

1.) Heat causes the tubing to soften and softer tubes are more likely to give.

2.) Thermal expansion and contraction. As materials heat up they expand. Different materials expand at different rates. Generally metals expand more than other materials. So, if the loop gets really hot, the metals in the fittings could expand just a tiny bit more than the rubber seals/tubing resulting in a leak.

I'm leaning towards the latter being the case in my system, as it has stopped since cooling down. This would be expected behavior for thermal expansion/contraction.


If the soft tubing were the cause, I'd imagine the leak would be permanent. The tube could loosen in the fitting while soft, and not go back again when it hardened up.
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in the case of an extremely high increase in temperature as you said you experienced, I can see it, are these compression fittings? I've no experience with them, I've always used standard barbs with either a slightly smaller ID tube than the barb or a zip tie wrapped around it, never experienced a leak. I wonder if maybe the fitting needs a slight tightening? like a quarter turn or something?

Were you able to determine exactly where it was leaking from on the fittings?
 
IdentityCrisis said:
in the case of an extremely high increase in temperature as you said you experienced, I can see it, are these compression fittings? I've no experience with them, I've always used standard barbs with either a slightly smaller ID tube than the barb or a zip tie wrapped around it, never experienced a leak. I wonder if maybe the fitting needs a slight tightening? like a quarter turn or something?

Were you able to determine exactly where it was leaking from on the fittings?
Click to expand...

Nope. I never actually saw the leak. Just dried coolant on the GPU backplate (from one of the CPU fittings) and on the top of the PSU (from one of the GPU fittings).

No matter what I have done since, I have been unable to recreate the leak. If I can't recreate the leak, I can't tell exactly where it is coming from.
 
Zarathustra[H] said:
Nope. I never actually saw the leak. Just dried coolant on the GPU backplate (from one of the CPU fittings) and on the top of the PSU (from one of the GPU fittings).

No matter what I have done since, I have been unable to recreate the leak. If I can't recreate the leak, I can't tell exactly where it is coming from.
Click to expand...

That's a bummer. I'd be interested to see if it was that vacuum theory mentioned above, have you opened your res up then did some benchmarking to get it warm? I suppose it a good thing you cant recreate it, but man that would make me nervous.
 
VanGoghComplex said:
I believe that you should buy an Aquaero.

Of course, I believe that everyone with a watercooled system should buy an Aquaero, so take that for what it's worth. XD
Click to expand...


I bit the bullet , sucked up my pride, and spent over $200 on a fan controller, and now that I ahve it set up, I agree, it is the best damned fan controller anyone could ask for.

I went for the flagship model with a screen and (accidentally) a remote. Had to mod my case to make it look good, but now that it is installed I like it.

upload_2018-12-30_3-41-30.png


At least during winter. We''ll see if I am still happy with it in warmer weather. I have it tuned pretty nicely now so that it -n based on loop temp - gives me silent operation unless I load it up. The challenge will come with higher ambient temps. I don't know yet how much faster that will make the fans spin. Time will tell.

The switches below go to my manual fan control unit. If I switch the rightmost switch from up to down, it goes from Aquaero to manual control.

The middle switch when down, allows manual or aquaero control when down, but goes to all fans off when switched up.

The dial on th eleft goes to my custom soldered PWM fan control board, and sends a PWM signal to the fans, so I can manually set them when in manual mode.
 
Zarathustra[H] said:
I bit the bullet , sucked up my pride, and spent over $200 on a fan controller, and now that I ahve it set up, I agree, it is the best damned fan controller anyone could ask for.

I went for the flagship model with a screen and (accidentally) a remote. Had to mod my case to make it look good, but now that it is installed I like it.

View attachment 131535

At least during winter. We''ll see if I am still happy with it in warmer weather. I have it tuned pretty nicely now so that it -n based on loop temp - gives me silent operation unless I load it up. The challenge will come with higher ambient temps. I don't know yet how much faster that will make the fans spin. Time will tell.

The switches below go to my manual fan control unit. If I switch the rightmost switch from up to down, it goes from Aquaero to manual control.

The middle switch when down, allows manual or aquaero control when down, but goes to all fans off when switched up.

The dial on th eleft goes to my custom soldered PWM fan control board, and sends a PWM signal to the fans, so I can manually set them when in manual mode.
Click to expand...
I like your manual override scheme!

The thing I've settled on for my Aquaero is the temperature delta between ambient and coolant temp. I get my ambient by averaging the temps from three sensors strapped to the fan hub spokes on the intake side fans of my rad, and the coolant temp is the average of two sensors - one at the beginning of my rads and the other at the end.

So... I expect that in summer, my components may run warmer, but my fans won't go faster. They only go faster if the difference between ambient and coolant gets larger.
 
VanGoghComplex said:
I like your manual override scheme!

The thing I've settled on for my Aquaero is the temperature delta between ambient and coolant temp. I get my ambient by averaging the temps from three sensors strapped to the fan hub spokes on the intake side fans of my rad, and the coolant temp is the average of two sensors - one at the beginning of my rads and the other at the end.

So... I expect that in summer, my components may run warmer, but my fans won't go faster. They only go faster if the difference between ambient and coolant gets larger.
Click to expand...

I wish there were a quick way to switch fan curves. You know, fan curve 1 for when I plan on doing something that stresses my hardware (games, heavy CPU work, etc) and curve 2 for when I plan on just putting around the internet and posting on the hardforum.

As it stands right now, I have a fan curve that is based on the max of two loop temperature sensors, one right after my CPU and one right after my GPU. (i don't expect them to ever be significantly different due to high flow, but just in case...)

I like to keep my GPU at under 40C when fully loaded in order to get the best core clocks, and I know my GPU fullcover block typically results in core temps 3-5C above my loop temp, so I have the fans spin up to keep my loop temps below 35C at all times.

I have two fan curves based on the same sensors, one for my top fans and one for my bottom fans. I control them separately because they are connected to different radiators with different fin density, and the denser thicker radiator has push-pull and the the thinner less dense radiator has push only, so if I just run them at the same PWM percentage, they won't spin at the same speed.

It looks like this:

upload_2018-12-30_20-7-32.png


I just hope the fans don't get too noisy at idle during the summer.

Right now, idle at the desktop with an ambient of ~18C, my loop is at 26.8C with my fans at 28% or ~480rpm.

I find that I can usually go up to 600rpm without th efnas being really audible, but I don't want to go above 600rpm. Now, I know fan rpm and PWM percentage are not linear due to the resistance of the radiators, but assuming that they are, I should hit 600rpm at about 35% PWM signal.

Per my current curves, this means I can hit about 34C loop temperature and still stap at 600rpm.

If we assume the offset is linear (which it isnt, because the faster the fans spin, th elower the delta T to ambient is) this means my ambient can rise by 7.2C to about 25C and my fans should still be reasonably quiet.

This is a pessimistic prediction though, as the delta-T to ambient is not fixed and will be smaller at 600rpm than at 480rpm, but I don't know by how much.

25C room temperature is 77F. I generally don't want to sit in my office on my computer at temps much above that anyway.

And either way, I guess it is a moot point, because in the summer in order to get my office below 80F, I'll need my window AC unit, and it is loud enough to completely drown out my computer anyway...

One of these days my dream will come true and I will have a house with central AC, but they are just so rare here in the Boston area.
 
Zarathustra[H] said:
I wish there were a quick way to switch fan curves. You know, fan curve 1 for when I plan on doing something that stresses my hardware (games, heavy CPU work, etc) and curve 2 for when I plan on just putting around the internet and posting on the hardforum.

As it stands right now, I have a fan curve that is based on the max of two loop temperature sensors, one right after my CPU and one right after my GPU. (i don't expect them to ever be significantly different due to high flow, but just in case...)

I like to keep my GPU at under 40C when fully loaded in order to get the best core clocks, and I know my GPU fullcover block typically results in core temps 3-5C above my loop temp, so I have the fans spin up to keep my loop temps below 35C at all times.

I have two fan curves based on the same sensors, one for my top fans and one for my bottom fans. I control them separately because they are connected to different radiators with different fin density, and the denser thicker radiator has push-pull and the the thinner less dense radiator has push only, so if I just run them at the same PWM percentage, they won't spin at the same speed.

It looks like this:

View attachment 131669

I just hope the fans don't get too noisy at idle during the summer.

Right now, idle at the desktop with an ambient of ~18C, my loop is at 26.8C with my fans at 28% or ~480rpm.

I find that I can usually go up to 600rpm without th efnas being really audible, but I don't want to go above 600rpm. Now, I know fan rpm and PWM percentage are not linear due to the resistance of the radiators, but assuming that they are, I should hit 600rpm at about 35% PWM signal.

Per my current curves, this means I can hit about 34C loop temperature and still stap at 600rpm.

If we assume the offset is linear (which it isnt, because the faster the fans spin, th elower the delta T to ambient is) this means my ambient can rise by 7.2C to about 25C and my fans should still be reasonably quiet.

This is a pessimistic prediction though, as the delta-T to ambient is not fixed and will be smaller at 600rpm than at 480rpm, but I don't know by how much.

25C room temperature is 77F. I generally don't want to sit in my office on my computer at temps much above that anyway.

And either way, I guess it is a moot point, because in the summer in order to get my office below 80F, I'll need my window AC unit, and it is loud enough to completely drown out my computer anyway...

One of these days my dream will come true and I will have a house with central AC, but they are just so rare here in the Boston area.
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Have you looked at set-point control in the Aquasuite software?
 
VanGoghComplex said:
I'd also argue that air trapped in your loop will expand far more with temperature than water will, so my guess is that a large quantity of air in your res will contribute to the pressure problem more than alleviate it.
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Air in loop - bad because it can bind the pump or reduce surface area on transfer surfaces.

Air would not make a pressure problem worse. Air is ~highly~ compressible. Adding more air doesn't change that, and while the pressure will change with temp, it isn't very drastic of a chance (ideal gas law and all).

Water is only very negligibly compressible, and if the system is hydraulically locked (i.e. no air bubble anywhere) the pressure will change by ~a lot~ when temperature changes, as it essentially behaves as a solid.

Diaphragm tanks used on water wells use this principle to help maintain constant pressure.

You should have air in your reservoir. You need enough liquid to make sure your pump never cavitates - beyond that it doesn't really matter how much liquid or air there is, so long as there is some of both. But you never want air in the actual loop or components themselves.
 
Brian_B said:
Air in loop - bad because it can bind the pump or reduce surface area on transfer surfaces.

Air would not make a pressure problem worse. Air is ~highly~ compressible. Adding more air doesn't change that, and while the pressure will change with temp, it isn't very drastic of a chance (ideal gas law and all).

Water is only very negligibly compressible, and if the system is hydraulically locked (i.e. no air bubble anywhere) the pressure will change by ~a lot~ when temperature changes, as it essentially behaves as a solid.

Diaphragm tanks used on water wells use this principle to help maintain constant pressure.

You should have air in your reservoir. You need enough liquid to make sure your pump never cavitates - beyond that it doesn't really matter how much liquid or air there is, so long as there is some of both. But you never want air in the actual loop or components themselves.
Click to expand...

Not just water wells. What we sort of imitating in these little water cooling loops: hydronic systems, always use expansion tanks (air) to buffer the pressure changes in boiler or chiller loops.
 
Just throwing my two cents into the ring. If you have a loop and ANY of your tubing gets really hot, then you are doing it wrong. :D

I've always been a big fan of using more radiator than is really needed in a loop - i.e. Excess. :) Find out what you need at a safe minimum as to radiators to handle your heat load... and then double it. Lots of high quality fans as well. And 1/2 ID tubing at a minimum. Also a reservoir with at least some air in it (20-25%) to allow for temp induced expansion in the loop. Air in a loop is actually a good thing... acts as a short of shock absorber... just so long as ALL of that air resides at the top of your reservoir or the top of your bleed off line and not anywhere else in the loop. If you are running a fully closed loop with reservoir and no air in the system anywhere, then pressure from thermal expansion or even your pump first starting up, isn't your friend and has to go somewhere... fittings/connections seeping are one way for it to go.
 
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Brian_B said:
Air in loop - bad because it can bind the pump or reduce surface area on transfer surfaces.

Air would not make a pressure problem worse. Air is ~highly~ compressible. Adding more air doesn't change that, and while the pressure will change with temp, it isn't very drastic of a chance (ideal gas law and all).

Water is only very negligibly compressible, and if the system is hydraulically locked (i.e. no air bubble anywhere) the pressure will change by ~a lot~ when temperature changes, as it essentially behaves as a solid.

Diaphragm tanks used on water wells use this principle to help maintain constant pressure.

You should have air in your reservoir. You need enough liquid to make sure your pump never cavitates - beyond that it doesn't really matter how much liquid or air there is, so long as there is some of both. But you never want air in the actual loop or components themselves.
Click to expand...
Good points, I was way off on my guesses.
 
Supercharged_Z06 said:
Just throwing my two cents into the ring. If you have a loop and ANY of your tubing gets really hot, then you are doing it wrong. :D
Click to expand...


I know. I have a fan kill switch for testing g purposes, and I accidentally left it so that I had no fans for a long gaming session. I didn't notice because my headphones were on.

Oops
 
Brian_B said:
Air in loop - bad because it can bind the pump or reduce surface area on transfer surfaces.

Air would not make a pressure problem worse. Air is ~highly~ compressible. Adding more air doesn't change that, and while the pressure will change with temp, it isn't very drastic of a chance (ideal gas law and all).

Water is only very negligibly compressible, and if the system is hydraulically locked (i.e. no air bubble anywhere) the pressure will change by ~a lot~ when temperature changes, as it essentially behaves as a solid.

Diaphragm tanks used on water wells use this principle to help maintain constant pressure.

You should have air in your reservoir. You need enough liquid to make sure your pump never cavitates - beyond that it doesn't really matter how much liquid or air there is, so long as there is some of both. But you never want air in the actual loop or components themselves.
Click to expand...


Good point, and a "duh" moment for me. I know this in theory but never thought of it in my loop.

I've always been topping off my reservoir to eliminate all air in it. This, combined with a hot loop during my "oops no fans" accident might have caused an over pressure situation.
 
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