PELLAQUA solar heating 12 m2 struggles to provide DHW in summer

[ENERC]

Have you drained the water heater recently?
There may be a good layer of brown mud at the bottom of the balloon which would cover the exchanger (iron oxides). I have already taken out a lot of brown sludge from a water heater.
You can do a sludge yourself (by emptying all the water, then by adding a little water by opening the hot water part so that the water arrives at maximum flow in the water heater to clean, then drain again) . it doesn't cost much.

[sicetaitsimple]

I am almost convinced that the secondary of the solar exchanger is "dirty".

Or a muddled "primary" after 10 years? The exchanger is still a low point of the entire solar circuit, anything that is solid particles is more or less likely to have accumulated there. Perhaps easier to treat, by disconnecting at the inlet / outlet of the tank and by attempting a high flow rinsing and / or circulation with a product, to see with a heating engineer?
It's just a guess.

Edit: post crossed with Enerc, but we are not talking about the same thing: him on the "secondary" side, me on the "primary" side.

[Philippe Schutt]

What are the characteristics of the solar pump? just to see if it's consistent with your speeds.

Sludge of solar circuits: if the panels exceed 150 ° (variable depending on the fluid), said fluid decomposes and forms sludge. However, if the circulator stops, the heat from the panel is no longer evacuated. And since your pump goes off all the time, you are screwing up your fluid.
I recovered HS panels, was able to retype 1 but the 2nd was completely blocked by the dried mud. Connected directly to the 4 bars of the network, nothing was happening.
AMHA that could be a lead.
@Christophe
my solar tank is heated in a thermosiphon from a plate heat exchanger. Of course it is not in the ball, I couldn't put it in. But it seems that this is what Ökofen did

[sylvain52220]

we read below the cursor, right?
do we read above the cursor?

A no it's either one or the other but not both at the same time!

At a time (bygone) on the internet we said RTFM ... In polite mode and in French it meant "Please look at the notice"

Otherwise it's a beautiful installation, having a flowmeter is rather rare!

In the photo, we see a graduation scale on the left which goes up to 13 l / min. For this scale, we can read the value pointed by the upper part of the float. If the float goes higher, we can no longer see its upper part, on the other hand with its lower part we can read on the right scale, which indicates 15, 20 l / min. I'm looking for the manual to be sure ...

[Christophe]

This is certainly why we must read the value at the bottom of the "needle" (or a mark above ...)

[Christophe]

@Christophe
my solar tank is heated in a thermosiphon from a plate heat exchanger. Of course it is not in the ball, I couldn't put it in. But it seems that this is what Ökofen did

Ah? Thank you for this info, I did not know that a plate heat exchanger could operate as a thermosiphon ... this may be what explains the inclined position in the okofen tank ??

Is yours tilted?

For the sludge it's also interesting what you say!

A solar system that stops in case of overheating, sorry I do not understand the principle !!

Tin solders start to suffer from 180 ° C under pressure it seems to me ... temperature that a modern solar thermal panel at standstill can reach in the event of a heat wave ... in my opinion it must relieve the calories but not stop?!?

[Philippe Schutt]

Well, I didn't think it might not work, so suddenly it works. For them, it is the fact of having a long enough heat exchanger and perhaps they have isolated the pipe that goes up.
At home, as it is on a common electric wall tank with the 2 connections below, I put the exchanger as low as possible. The ideal is to have a tank on the ground with the hot water outlet at the top, this gives the height of the tank for the pump effect.
My exchanger is not tilted. I don't think it has an effect. it is much smaller, but it is 50cm lower than the ball.

We try to limit the temperature in the balloon to around 90-95 °, it's not a steam locomotive
otherwise, large expansions, risk of burns, pvc pipes which soften etc ... Expansion vessels do not like either.
With evaporative tube panels there is self-regulation because the heat transfer by condensation no longer takes place, so we shut off the circulator and let the temperature of the panels rise.
With flat panels, from 75-80 ° in the balloon, the heat puncture is reduced so that the panel rises to a little below the decomposition T ° of the fluid, so it re-emits more into the air. By slowing down the circulator or intermittent operation. And we run it at night to cool the balloon by heating the panels.
I have never seen solar systems that would throw out the fluid. They prefer to let the pressure build to prevent it from muddying. And not seen any tin solders in the panel loop.

The gap between the plates of the exchangers is not very important, it can become blocked with sludge. The copper pipes of the panels too, maybe even more. Hence the need to see the flow curves of the circulator.

[Christophe]

The gap between the plates of the exchangers is not very important, it can become blocked with sludge. The copper pipes of the panels too, maybe even more. Hence the need to see the flow curves of the circulator.

This is why I am quite surprised that a thermosyphon works with a plate heat exchanger which contains lots of baffles ... the fluid must therefore go down as much as it must rise ... in short, a good thermosyphon requires the minimum pressure drop ...

But if you say it works I believe you ...

A submerged fin heat exchanger would work much better, right? But if Okofen has really put an immersed plate heat exchanger in a thermosyphon, it is because it works. It's just amazing ...

Yes for fouling, we thought about it above, hence the questions on the flow (which seems good ... so not really clogged but that does not mean that the internal surfaces of the exchanger are not dirty ...) ... A good blow of karcher inside should see what comes out of it!

If it is the scaled secondary, without the possibility of disassembly ... You just have to change the balloon

[Macro]

He could already get an idea of ​​the fouling of his balloon .... Quite simply by opening the purge valve at the low point ... If the water is very hard in his region ... Logically he does not should ... Nothing flow .... If fine sludge flows ... With a bit of luck they were not driven by thermosyphon into the plate heat exchanger ... but only blocked its low inlet. ... the balloon is reputed to have an inspection hatch to graft a standard electric resistance .... The hole is not very big .... In general it allows a hand to enter ... Without power take it out with a handful of limestone crystals ... But it allows you to vacuum a hose .... I say that but with all the mess that this balloon contains ... it's far from being won. ...

My house boiler is equipped with a cylindrical DHW tank in horizontal position .... This tank is equipped with an internal coil ... this coil is connected directly to the boiler heating body without a circulator ... And it works very well .... Since 1973 .... Yet without a softener, with very hard water .... Like what .... It is not useful to want to reinvent hot water .. ..

[sylvain52220]

If it is the scaled secondary, without the possibility of disassembly ... You just have to change the balloon

I think the analysis has been quite thorough now and I will insist on having a technical :-) exchange with someone from Okofen to see if they confirm our explanations and see a solution.
If the fouling of the solar exchanger is confirmed and no effective solution is considered by Okofen, you will surely laugh, but we are discussing to install an inspection hatch ourselves in a well chosen place (ie without risking 'damage the heat exchanger itself or another coil) to be able to deal with the problem regularly ... It's steel, it discs, it welds well and the pressure is not either huge (<2bar) so we should be able to seal with a door / flange ...