Junkers Novatherm ZW 20 KD - letni tryb pracy / summer mode not working

Hello
Sorry for English, but it seems that this forum is the only place where people knows something about Junkers boilers ) Feel free to answer in Polish, i understand it well, just can't speak.

I have a problem with Novatherm ZW20KD: the heating continues even when regulator on the boiler is in "summer" position:


It seems that this regulator is not working at all, boiler keeps firing every several minutes regardless of regulator position and current temperature. What reasons can cause this? What of this reasons can be fixed or checked by myself? If repair is too complicated, is there a way to just disable heating for now (to make it work in summer mode permanently)? For example by plug in there

some fake "regulator" that will make boiler think that it's too hot in the room

Thanks

Może być uszkodzone ( złamane) pokrętło do regulacji c.o. Może też być wytarty potencjometr na płycie. By wyłączyć c.o. można wypiąć zworę ze styków 1, 4.

12B napisał:

By wyłączyć c.o. można wypiąć zworę ze styków 1, 4.

Great great thanks! That's exactly what I need. I didn't even hope that it is so easy

Now I have time till next winter to fix it completely

... two hours later


Guilty!

Testing if everything else works...

Pins 1 and 4 are shorted and everything is fine (no CO but CWU ok)
So it looks like I just need to find a new potentiometer

Thanks for help!

12B napisał:

Może być uszkodzone ( złamane) pokrętło do regulacji c.o. Może też być wytarty potencjometr na płycie. By wyłączyć c.o. można wypiąć zworę ze styków 1, 4.

Widzisz Bodzio. Już możesz robić za granicą. Dogadałeś się? Dogadałeś!