Posted Wed Jun 27, 2012, 10:58am Subject: Re: Gaggia Espresso machines w/out OPV - how is pressure regulated?
Glad the explanation helped.
You will get a lot of argument about it being an elegant solution. Most people just absolutely hate the valve and blame it for not getting enough (or not consistent) brew pressure. It is pretty much universally despised and one of the first mods people make to their Gaggia is to plug it up.
Myself ... I don't believe the valve affects brew pressure at all (unless it is really stuck/damaged/leaking badly - though most will say they all fit that description or soon will). I've plugged a few and not missed it - enjoyed having one less hose dangling in the water tank. I've left a few in place and and not been bothered by it. It just isn't the big deal it is made out to be.
If I had a machine that was leaking horribly from that valve I would probably just plug it rather than try to clean/fix it.
I'm so in the habit of simply opening the steam valve when I prime a dry pump or top up an empty boiler so the valve isn't really needed.
DansCoffeePhase Senior Member Joined: 2 Dec 2009 Posts: 31 Location: OK Expertise: I love coffee
Espresso: Gaggia mod (PID+OPV+3way) Grinder: Cunill Brasil Roaster: TC/CO
Posted Thu Jul 26, 2012, 6:49am Subject: Re: Gaggia Espresso machines w/out OPV - how is pressure regulated?
Here's some data from a very unique setup: before/after static pressure measurements from replacing a Gaggia group valve boiler with a 3-way valve boiler. My modded machine also has a high quality Quickmill OPV, installed away from the boiler, which wasn't disturbed at all by the swap.
For the last 3 years my portafilter mounted pressure gauge consistently read 145 psi static. After installing the 3-way valve boiler the same gauge read 185 psi. I had to turn the OPV nut 2 full turns to lower the pressure to 145 psi.
I usually kept the group valve nut backed off 1/4-1/2 turn, but I'm still surprised by the 2.75 bar (40 psi) difference.
BTW, I love the 3-way valve setup. My main reason for doing this mod is I HATEHATEHATE cleaning the group valve weekly (sometimes daily) to stop drips & leaks! Even a small leak of a few drops/minute will soon drain half the boiler which results in a way too low brew temperature (sour shots).
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