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Can someone please explain what exactly is happening in the OPV valve when it starts to squeal? I noticed this when trying to reduce the pressure. I was able to drop the OEM pressure from 13 to 11 bar. Anyting beyond that causes a squealing sound - which seems like something to avoid.
- Team HB
That was a good explanation. I'd like to add I've had luck ending the squeals by just disassembling and reassembling.
So if I understand correctly, the squealing is more a matter of harmonics rather than the valve being on the verge of popping off the threads. So if I drop the brew pressure a bit more will the squeal go away?
If their explanation is correct, changing the pressure (either way off the resonance point) should do it.
- Supporter ❤
Maybe, maybe not. Sometimes it can be dead quiet with the covers off and start squealing two days later, only to quiet again with the cover off. Sometimes rotating the adjuster in and out and back to original position can work. Also some HiTemp silicone grease in the spring cups doesn't hurt. [Lasts longer when the OPV is in the cold side]Pressino wrote:changing the pressure (either way off the resonance point) should do it
Depending on OPV design and age, flipping the rubber puck to put a new face on the seal sometimes works. If the puck is toast, a replacement may be available.
Ian's Coffee Stuff
- Team HB
What's worse is the fact that sometimes a new rubber valve face makes it worse than the old hard one it replaces. Sometimes the green rubber ones that are supposed to be used when the OPV is dual-purposing as the expansion valve are worse than the black rubber ones.