hi,
after changing the magnet valve responsible for boiler filling/"fresh water in the HX circle" in my L6 one problem still remained (occurred only one time in months): the water level of the boiler sank, hot water entered the pump and fresh water tube. i still dont understand the function of the magnet valve at the back of the machine as a whole. if i start the machine (on switch on) the valve "clicks" one time and the heating element starts heating the water in the boiler. if the pump is on and i press the "filling" switch in the middle (mine is blue) the boiler water level increases, if the pump is not working hot water runs into the pump due to the boiler pressure. all this seems reasonable to me. the machine is not connected to the water supply but to a reservoir. why is there a first klick before heating up?
the only explanation i have for hot water entering the pump after the machine is heated up is that the rear magnet valve opens. is this problem familiar to you? could it arise from a defect gicar box, contact problems of fill level metering or sth else?
kind regards, arcimboldo

Is the wire going to the boiler fill probe disconnected? If it is, then that would cause the machine to think the boiler is empty and try to fill it. Also, the pump would kick in at this stage.

Post a pick of your machine internals.

It is possible for the non-return valve to be leaking and therefore hot water from boiler going backwards due to boiler pressure.

thank you for your reply.
if you look at the picture there is a part marked with "?". is this the non-return valve you mentioned? i dont understand the function of this part. after the extraction the HX circle is pressure free due to the other magnet valve below the brewing unit. if there is pressure in the HX circle (during extraction) the pump prevents back flow through the non-return valve.

is there also a first "click" sound before heating up with your L6?

No click on startup, except if the machine is low on water and it needs to fill the boiler up.

Hot water in pump circuit can be caused by a couple of things - the solenoid 'click' means your fill circuit is open and or
- non return valve leaking meaning water can flow backwards from HX circuit when heating up due to expansion of water

It seems your 'click' means solenoid is opening. It could be due to wire on fill probe being disconnected or ground wire going to brain box not making proper contact or being loose.
I would concentrate on that click noise because that should only happen if the boiler is low and the machine is filling it up.

Thank you very much for your reply.
The first click before heating up has to be a short open-close signal. This happens before every heating, also while running. I forgot to mention this. But, as i sayed, its a short open-close click since the pump keeps cool. If the cable is disconnected from the waterlevel indicator the machine start filling the boiler. So the open-close click before heating is a misfunction and the original problem of HX water entering the pump (occured only 1 time since i bought the new magnet valve) should be related to this open-close error. How can i check the control (gicar) box? Where could be the connection between heating up and magnet valve? can anyone show me a picture of the cabeling in his pressure controle box?
I hope i could get my ideas across ...
kind regards
PS: wiring is new an all contacts are fine

The click is unrelated to the problem - it's the sound of the fill valve opening when it needs to open.

But - hot water flowing backwards to the pump (or flowmeters if the machine is an automatic) is bad - these components are made to handle cold water only - you should fix this immediately - a hot pump won't last.

There is a one-way valve (all brass, not an electrovalve) located along the cold water path towards the heat exchanger - it's what you need to repair. It's a simple spring/plunger mechanism.

thank you, yes it is the one-way valve that caused the problem (hot water flowing back towards pump).
how can i fix the click problem when heating?

Here is a link to a video showing the machine while heating (machine already heated up)
https://www.dropbox.com/s/3m9r7fu6o55cu ... 1.mp4?dl=0
hope you can hear all the sounds. meanwhile i changed the gicar box, the behaviour is the same.
i wonder about the short "click" on/off after the light shows the beginning of the heating. there are three separate click sounds, one simultaniously with the red light an the click on/ click off shortly after this. i wonder about the two last clicks made by the EMV showed in the picture above.

nobody with a L6 here?