Post By shadow745
Rancilio Silvia- steam is returned via hose back to tank
hope this make sense. After cleaning the machine when start rancilio, it appears the steam is transferred via hose back to tank and it bols the water un tank. Ive opend up and there is bo any obvious a’loose’ part.
what shall i do?
Sounds like your OPV (over pressure valve) might be sticking open. This part controls the brew pressure, but also holds back pressure in the boiler when the machine is ON and sits idle. If the plunger in it doesn't have a good seal/or spring worn (not likely) it can let heated water/steam escape and route back to the reservoir.
You mentioned cleaning the machine... can you describe the process?
Ive used a powder soap into portafilter to clean the grouphead, ran the water few times untill water clears. Thats the ocasional clean i do, nothing major.
What do u suggest i do next, i opend up machine but there was nothing appears ‘loose’, where is opv lcated?
thank u for your help!
Originally Posted by shadow745
Attached is a pic of the adjustable OPV. Older machines have a non-adjustable OPV of a slightly different design. Unplug machine and do this when it's cool. The OPV has two hoses... one is threaded on one side and is fed by the pump, which is pressurized. Don't bother with that hose. The hose on the opposite is the overflow back to the reservoir and that is the one you want to remove. Just pinch the clamp open and slide down the hose, then pull it off the OPV nipple. Without reinventing the wheel here is a link that will explain what to do...
Recently my Silvia OPV was stuck completely shut and I noticed it immediately when backflushing as the OPV will divert excess pressure back to the tank. I let the machine cool down, took OPV apart and really found nothing wrong at all. No parts wear, no blockage, etc. Made sure all was clean, put back together and it's been flawless since. Likely just a one time hiccup.
**You could try a descale of the boiler, steam wand, etc. and there is a way to descale the OPV without taking anything apart, but in all honesty it's quite easy and quick to just take it apart and inspect/clean mechanically.