Thermal buffer: avoid surface evaporation of hot water with oil or other blocking product?

[Christophe]

...
Maybe there is no air intake simply because the pressure drops and the diameters of the pipes are sufficient for the water to fall under the action of gravity?
...

How could water sink if its volume is not compensated with air?

Yes I know it's weird...

Either there is always a part of it (slightly compressed by the water) or is it cavitation that produces it? I have about 12 m of fall anyway... it's a hell of a suction...

Either there is an air leak that I haven't discovered yet...

At home, the water goes back down when the pumps stop, the meters turn upside down, and the pumps too. (I have fans in parallel with the pumps, they turn during the descent, powered by the pumps).

At home too: but the water that is in the return comes down through the return...

What's this story about a fan powered by pumps?

[Christophe]

you forgot this:
.... which would mean that it wouldn't cost anything in the end (oh yes, a Weekend of elbow grease and the hardware: aluminum crosspieces and PVC supports + concrete pads, galvanized wire * and stainless steel screws! And this for ZERO HASSLE)...

But how heavy it is!
Christophe, can you tell him once and for all that apart from being a cave diver it is impossible to intervene in this capacity?
And if not, invite him really "a Weekend" to mount his false ceiling, you offer him lodging, cover and with a little luck a good Legionnaire's disease....

Already said X times but he listens to nothing and he compiles nothing...we're used to it...

[dede2002]

...

What's this story about a fan powered by pumps?

pumps 12-2022.jpg (162.34 KiB) Viewed 531 times

On the left, two PC power supply fans in series. Powered by the same relay as the pumps, they turn when it empties. It seems to me in the same direction...

It's 24V DC three-phase pumps, and the current goes back through the controllers.

[sicetaitsimple]

Either there is always a part of it (slightly compressed by the water) or is it cavitation that produces it? I have about 12 m of fall anyway... it's a hell of a suction...
Either there is an air leak that I haven't discovered yet...

There is undoubtedly a slight degassing of the gases contained in the water when your circuit goes "under vacuum" during emptying, but that certainly cannot be the explanation given the still certainly large volume of your solar circuit.
Similarly, not for "cavitation", but for a "vaporization" of the hottest water in your circuit when it triggers.
But by the way, are you sure that your circuit drains quickly, as was certainly the case before you removed what you call "bleeders"?
I don't know if your pump is submerged or not, but if it isn't, do you see if it backfires when draining?

[A.D. 44]

Wax on the heat exchangers...

And ? They are submerged and the wax floats...you have to follow a minimum before opening it and look like a fool...

Or are you thinking of something else???

If you are certain that it will float above, without ever being in contact...so much the better.

Otherwise open it... Yes it can happen to me (modestly).

As for passing for an idiot... I don't care at all. But then, totally.

It is always a real pleasure to discuss with you.

Good continuation.

[Christophe]

No I'm not sure but what is the problem if there is wax in contact with the exchangers? Which is solid or liquid?

We answered above: the heat transfer coefficient of liquid wax is good, better than water...and in any case the "waxed" surface will be tiny compared to the rest of the surface of the exchangers...

So sorry but I don't see the problem??

[Christophe]

But by the way, are you sure that your circuit drains quickly, as was certainly the case before you removed what you call "bleeders"?
I don't know if your pump is submerged or not, but if it isn't, do you see if it backfires when draining?

It drains in a few seconds after a dead time of about 5 seconds (never measured)...it's just a little longer than when the traps were "open" where the drain was immediate.

Oh, I forgot to specify: when I was working on the roof at these traps and the solar pump was running and there was a nice suction of air! We could hear it several meters away...That's why I quickly decided to isolate them with a valve at first (I could have removed them completely and finally put a cap on, but going up the top is no easy task!) .

Now I'm not sure that these 2 valves are perfectly vacuum-tight...nor to the installation and even less after 10 years outside

The pump is not submerged and yes, it runs backwards when emptying...but the water that is already in the return probably does not come up when emptying...

The best would have been to put solenoid valves (NO and closed when the pump is activated) instead of the 2 purgers but I never found the courage to do it... and then it still ends up messing up a solenoid valve even more when they are outside...

[sicetaitsimple]

It drains in a few seconds after a dead time of about 5 seconds (never measured)...it's just a little longer than when the traps were "open" where the drain was immediate.
Oh, I forgot to specify: when I was working on the roof at these traps and the solar pump was running and there was a nice suction of air! We could hear it several meters away.../u]

Ah well, you see, I was right when I said that the function of these "bleeders" was more of a "vacuum breaker" function.
Well, if it drains well, that's the main thing...

[sicetaitsimple]

No I'm not sure but what is the problem if there is wax in contact with the exchangers? Which is solid or liquid?

The potential problem, with solid wax which would have deposited on an exchanger which is "cold" by nature, is that you will reduce (physically, by reducing the passage sections) the natural convection flows of the water in your buffer between the tubes and fins of your exchanger, and therefore create a "more or less cold bubble" around it.

[Christophe]

It drains in a few seconds after a dead time of about 5 seconds (never measured)...it's just a little longer than when the traps were "open" where the drain was immediate.
Oh, I forgot to specify: when I was working on the roof at these traps and the solar pump was running and there was a nice suction of air! We could hear it several meters away.../u]

Ah well, you see, I was right when I said that the function of these "bleeders" was more of a "vacuum breaker" function.
Well, if it drains well, that's the main thing...

I never said you were wrong (on this one...) but I just didn't know the name empty case...

In this case, it was more air suckers (aspirair?) than empty breaks!