How does my heating system with solar thermal work?

Hello

No, that is a safety valve.
The air separator is underneath. It can be vented at the air screw under the red lever.

Olli

Ah, I see. Yes, I had also bled it myself until a drop of water came out. However, that was before it was flushed for the first time, I don't even know if I did it again afterwards?! I will check!

Too early to celebrate...

About 7 weeks ago we rerouted the pipes (they no longer run up to the ridge but over the attic to the collectors), so the collectors are now the highest point. The heating technician then connected the pipes (the supply line had to be extended by about 2m), refilled the system and then flushed it --> after that everything ran perfectly fine until about a week ago, in my opinion! On Sunday just before noon (since then I have regularly checked the control system values, if possible several times a day), I noticed the temperature at the roof was >130°C and accordingly the pump was of course not running. That immediately gave me the bad suspicion that it’s starting again, because I assume that if the circulation is working properly, the temperature at the roof does not reach such a high temperature or not so quickly. (There were days that were much sunnier and especially sunny for longer periods and I never saw more than 85°C on the roof and the temperature in the stratified storage tank was pumped up to >51°C and it has 800 liters volume after all!) A few days later I saw >70°C at the supply line below again, but both the return flow and the temperature in the storage hardly increased. Since yesterday nothing is working again --> supply and return stand as if nailed at ~20°C although the temperature from the roof is high and the pump is controlled and also running until the threshold is exceeded again and it switches off... The system must be tight, the pressure is always about ~2.5 bar or sometimes goes above >4 bar when the temperature at the collector rises (sometimes >150°C...). What I find strange: with my collectors (4 pieces) both sides, i.e. supply and return, are connected at the top! (So the supply line on the right module at the top and the return on the left module at the top!) All other collectors I have seen around here are connected at the same module, top and bottom! However, my heating technician said that there are also collectors where both pipes are connected at the top... My system is by the way with heating support as it turned out, does this still play a role? The last possibility that occurs to me as a layman would be to install an air separator directly at the collector at the top (i.e. at the highest point), right? One more question about the stratified storage tank: Does the size of the storage actually have the disadvantage that if, for example, no sun shines in winter or as in my case the system does not work, much more gas is consumed because much more domestic hot water has to be heated? It seems to me anyway that the heating constantly has to heat (when the solar thermal was still working properly, we sometimes didn’t need any gas at all according to the gas meter!). Many thanks in advance for your time and effort! Best regards

Since you write "with heating support" maybe there is a 3-way valve that does not switch? That means as long as the house is heated it works, but when it's only warm water it no longer does.

Hi
have you in the meantime also bled the air separator again?
It also collects the oxygen released from the liquid after commissioning.
An additional venting option only helps if it is actually used.

Which type of collector is installed? You can compare the installation instructions with the actual installation.

Please post some pictures showing the path of the solar lines
a from the buffer to the pump station and
b from the pump station to the shaft.

Olli

First of all, thank you very much for your time and effort!

Since you wrote "with heating support," maybe there is a 3-way valve that does not switch? That means as long as the house is heated it works, but when only hot water is left it doesn't anymore.

Good idea, something was also unusual, my heating technician said: Unfortunately, I don't remember exactly, some valve or something is located in the supply line and "normally" in the return line or vice versa. The function is supposedly given.
What I can say for sure is that since Sunday it has not worked either when heating is on or when only domestic hot water is heated. (It is always only 20°C at the supply and return lines even though the pump is running and there is sufficient heat at the roof!)

Have you also bled the air separator in the meantime?

I did. Quite a bit of air came out, but this did not improve anything. When I bleed now, fluid comes out immediately.

Which collector type is installed? You could compare the installation instructions with the actual installation.

I think they are Delphis, I will check the exact type in the invoices. I will definitely contact Delphis to see if the connection at the top for supply and return lines is correct!

Please upload some pictures showing the routing of the solar lines
a from the buffer to the pump station and
b from the pump station to the shaft.

On Wednesday I will take appropriate pictures and upload them here! One more question about that: What do you mean by shaft? The lines go through an unused flue of a chimney to the roof. Is that what you mean?

Thanks again!

Regards