Hi folks. I've a problem that my Silvia boils the water in the boiler. Before reaching boiling point water, and eventually also hot steam, flows through the over pressure hose back to the water reservoir.

Especially in the steam mode the excess steam comes furiously out of the over pressure hose causing loud noise. I've tried to tighten the over pressure valve by 90 degrees but that didn't seem to affect this at all. The water pressure out of the group head is ok in my opinion.

Here is a video to illustrate the problem Do you think that the malfunctioning OPV could cause this?

OPV will be the first place to look at,

but also figuring out if the brew thermostat is working properly and is not shutting off way after the set point,

also (I cannot see it in the video) is there any water at all coming out from the grouphead?
if not you might have issues there as well, something clogging the passages and diverting all the flow to the OPV

Thank you for the answer! No, in video there isn't coming any water out of the grouphead because I only had hot water and steam switches on. Brew switch works normally and delivers water out of the grouphead.

How could I check the OPV? Can it be dismantled by unscrewing the valve?