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Discussions > Espresso > Espresso Mods > Help OPV Grimac...  
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Lifestar
Senior Member
Lifestar
Joined: 2 Dec 2005
Posts: 236
Location: Howell, MI
Expertise: I love coffee

Espresso: Grimac Mia
Grinder: Baratza Vario, Rocky, KAP
Drip: FP, TV, Aerobie
Roaster: HotTop P, I-Roast2
Posted Mon Dec 24, 2007, 8:41am
Subject: Help OPV Grimac MIA
 

I am looking to adjust down the pressure on my OPV valve on my GRIMAC MIA.  Doing a cheep portafilter pressure check it is topping out over 11 BAR (Where my gauge ends.)  the next two posts will show what appears to be a brass block with lots of tubes in and  out of it that appears to contain my OPV.  Problem is I have no idea how to adjust it.  I am wondering if I could add a secondary OPV right off the vibe pump that I could set lower.  Being an HX machine this would also be in-line for the boiler fill as well but I imagine that that could be a problem.  Anyone with thoughts on either how to adjust what I have or on adding the second OPV?  (Any water drops in the picture is the result of my removing the tank not any leakage)

The OPV flow tube is the top tube on the right.

Lifestar: boiler MIA.jpg
(Click for larger image)

 
Robert Kolm
Howell, MI
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Lifestar
Senior Member
Lifestar
Joined: 2 Dec 2005
Posts: 236
Location: Howell, MI
Expertise: I love coffee

Espresso: Grimac Mia
Grinder: Baratza Vario, Rocky, KAP
Drip: FP, TV, Aerobie
Roaster: HotTop P, I-Roast2
Posted Mon Dec 24, 2007, 8:43am
Subject: Re: Help OPV Grimac MIA
 

Closeup of the block

Thanks for the help and Merry Christmas everyone.

Lifestar: opv.jpg
(Click for larger image)

 
Robert Kolm
Howell, MI
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kitt2000
Senior Member
kitt2000
Joined: 29 Apr 2007
Posts: 229
Location: nelson, new zealand
Expertise: I love coffee

Espresso: Lambro,
Grinder: Mazzer SJ
Roaster: Gene cafe
Posted Wed Dec 26, 2007, 4:23am
Subject: Re: Help OPV Grimac MIA
 

Hi, i've got the older model grimac mini or la-uno, it has exactly the same block!! I wasn't sure if it was the opv at first, but after adjusting it , i'm sure it is.It made a big difference to the shots.I was getting quite under-extracted shots before the adjustment.The larger brass nut under the tube that returns to the tank is the one you want to turn in a anti-clockwise direction to lower the pressure.I turned mine about an sixth of a full turn.
There are figures somewhere on this site to check approximate water amounts the opv should be returning to the tank under a blind shot.I think it's around 50-55mls in 30 sec's, but i'm not sure-depends on the pump model also.
make sure to check for leaks after adjustment-mine was fine, but can't hurt to check.
Hope this all helps
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Lifestar
Senior Member
Lifestar
Joined: 2 Dec 2005
Posts: 236
Location: Howell, MI
Expertise: I love coffee

Espresso: Grimac Mia
Grinder: Baratza Vario, Rocky, KAP
Drip: FP, TV, Aerobie
Roaster: HotTop P, I-Roast2
Posted Wed Dec 26, 2007, 6:46am
Subject: Re: Help OPV Grimac MIA
 

Super thank you.  I rigged up a portafiler pressure gauge so I can test while I am adjusting.  Thanks for the help.

 
Robert Kolm
Howell, MI
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Lifestar
Senior Member
Lifestar
Joined: 2 Dec 2005
Posts: 236
Location: Howell, MI
Expertise: I love coffee

Espresso: Grimac Mia
Grinder: Baratza Vario, Rocky, KAP
Drip: FP, TV, Aerobie
Roaster: HotTop P, I-Roast2
Posted Thu Dec 27, 2007, 8:49am
Subject: Re: Help OPV Grimac MIA
 

Needed to add a O ring to keep it from leaking but its now at 9 BAR.  After several nice shots however my boiler dropped pressure and will not heat.  I can't see how it is related just my dang luck.  Going to move the machine from the bar to the shop to either fix it or prep it for shipping to a repair shop.

 
Robert Kolm
Howell, MI
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Salty
Senior Member


Joined: 2 Jul 2013
Posts: 2
Location: Zimbabwe
Expertise: Just starting

Posted Thu Jul 18, 2013, 7:23am
Subject: Re: Help OPV Grimac MIA
 

Hi, I know this was a long time ago but is there any chance that you can send me more close up pics of the wiring.  I have one that has been messed with so I need to know that everything is plugged in to where it should go.  The switch on the pressure valve, the attached wires to the Gicar unit.  Basically anything that will help me to trace things to where they should be.  Many thanks
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calblacksmith
Moderator
calblacksmith
Joined: 25 Nov 2007
Posts: 7,675
Location: Riverside, Ca, U.S.A.
Expertise: I live coffee

Espresso: ECM Vene. A1, La Cimbali M32
Grinder: Azkoyen Capriccio, Major
Vac Pot: 40s era Silex
Drip: Msl. Com. brewers
Roaster: gave it a try, decided no
Posted Thu Jul 18, 2013, 9:59am
Subject: Re: Help OPV Grimac MIA
 

It has been about 6 months since he logged in, you might try giving his public email account a try.

 
In real life, my name is
Wayne P.
Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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