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Date: 05 Jul 2007 00:58:50
From: Robert Harmon
Subject: OPV/PRV and the need to adjust them.
Because of the number of questions, comments, and just rude replies, to my
post about the Gaggia Classics with incorrectly adjusted OPV/PRV's, I
thought we might delve into the topic in more depth.

First, I'll state my assumptions and then encourage everyone to pile on. I'd
ask that replies be categorized as assumptions, facts, & CW.

Fact: If you've personal & first hand knowledge based on scientific or
empirical testing, that's fact.

Assumption: If you're following the advice of named individuals and believe
it to be good advice, that's an assumption.

CW: Conventional Wisdom; If you're doing something because everyone else is
doing it, that's CW.

CW;

* fresh roasted beans are best if used within 1 - 2 weeks

* espresso is best brewed ~130psi (9 bar) & at ~196F.

* three things affect the flow of a shot

1) pump pressure

2) OPV/PRV setting

3) grind/dosing/tamping of beans

If the pump passes a water debit test it's assumed to be functioning
properly (most vibe pumps are capable of 14 - 17 bar). If the OPV/PRV is
properly adjusted the brew pressure will be limited to ~9 bar, with the
excess being redirected to the water reservoir. If the beans are freshly
ground & of the proper degree of fineness, and are tamped consistently, the
resulting espresso shot will be 1.5 - 2 ozs in 25 - 30 seconds.

Assumptions;

It's best to establish that the pump & OPV/PRV are functioning properly
before attempting to master dosing techniques. If the brew/group pressure is
set too low the coffee must be ground coarser and/or tamped less, resulting
in under extracted coffee. If the brew/group pressure is too high the coffee
must be ground finer and/or tamped more, resulting in over extracted coffee.

Ideally, once the brew/group pressure is adjusted to ~9 bar it can then be
ignored. CW holds that tamps should be consistent from shot to shot, light
to firm is up to you. That leaves the grinding of the coffee beans as the
only variable. If shots finish before 30 seconds, or begin to blond, adjust
the grinder to a finer setting. If the shots don't finish by 30 seconds,
adjust the grinder to a coarser setting.

Fact;

I tested seven Gaggia espresso machines brew/group pressure and all had the
OPV/PRV adjustments wrong.

Opinion;

In pressure testing seven Gaggia espresso machines I found that, as they're
shipped from the factory, Gaggia machines over extract coffee and aren't
producing the shots they're capable of and consumers are entitled to.
Whether this is because of lack of proper quality assurance or whether
Gaggia is intentionally setting the pressure high for their own reasons is
moot. What's important is that the espresso machines are reaching the
consumer with improperly adjusted OPV/PRV's.

Comments?
--
Robert Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.

http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.

http://www.tinyurl.com/2cr3e2 - I have things for sale here.






 
Date: 20 Jul 2007 11:31:10
From:
Subject: Re: OPV/PRV and the need to adjust them.??
On 9 Temmuz, 21:54, SJM <cajamadimail-goo...@yahoo.com > wrote:
> On Jul 6, 10:05 pm, TimEggers <timegg...@hotmail.com> wrote:
>
> > I can understand the cost issue, but still I would think it to be
> > worthwhile if not standard then as an option. I for one would happily
> > accept the added cost (if I didn't have Anita).
>
> I need to eat a bit of crow here.
> Although it seemed to me that I had adjusted the OPV of my Gaggia
> Coffee, and indeed I think I did, it seems to me now that I actually
> adjusted it too low. And, in trying to re-adjust it, I have run up
> against a wall. The screw seems to be stripping out and I can't seem
> to get any reasonable level of adjustment. So, although I still think
> that lowering the pressure did make the shots sweeter, I seem to have
> lost the adjustability capability, and am (maybe) now stuck with
> whatever it is going to give me.
>
> In retrospect, Gaggia has definitely messed up by neither adjusting
> the pressure properly before shipping the machines nor giving the
> customer a reasonable way to make those adjustments to his/her
> preference. (I would prefer the second route, myself)....
>
> Do any modern Gaggias have adjustable OPV's? My experience is only
> with old (OLD!!!) Gaggias or with the newer Coffee and Espresso
> models.
>
> SJM

Modern Gaggias are worst. Consequently they ate crow (workshop
closed).

David



 
Date: 09 Jul 2007 11:54:12
From: SJM
Subject: Re: OPV/PRV and the need to adjust them.??
On Jul 6, 10:05 pm, TimEggers <timegg...@hotmail.com > wrote:
> I can understand the cost issue, but still I would think it to be
> worthwhile if not standard then as an option. I for one would happily
> accept the added cost (if I didn't have Anita).

I need to eat a bit of crow here.
Although it seemed to me that I had adjusted the OPV of my Gaggia
Coffee, and indeed I think I did, it seems to me now that I actually
adjusted it too low. And, in trying to re-adjust it, I have run up
against a wall. The screw seems to be stripping out and I can't seem
to get any reasonable level of adjustment. So, although I still think
that lowering the pressure did make the shots sweeter, I seem to have
lost the adjustability capability, and am (maybe) now stuck with
whatever it is going to give me.

In retrospect, Gaggia has definitely messed up by neither adjusting
the pressure properly before shipping the machines nor giving the
customer a reasonable way to make those adjustments to his/her
preference. (I would prefer the second route, myself)....

Do any modern Gaggias have adjustable OPV's? My experience is only
with old (OLD!!!) Gaggias or with the newer Coffee and Espresso
models.

SJM



 
Date: 06 Jul 2007 22:05:48
From: TimEggers
Subject: Re: OPV/PRV and the need to adjust them.??
I can understand the cost issue, but still I would think it to be
worthwhile if not standard then as an option. I for one would happily
accept the added cost (if I didn't have Anita).




 
Date: 05 Jul 2007 21:50:13
From: TimEggers
Subject: Re: OPV/PRV and the need to adjust them.
Thanks for the link Craig, I have seen that before and I appreciate
it.

I did adjust my valve and I didn't see any affect. Oh well it's of no
matter now that I have Anita!

Cheers!





 
Date: 05 Jul 2007 12:14:33
From: mocha
Subject: Re: OPV/PRV and the need to adjust them.
On 5 Temmuz, 20:44, TimEggers <timegg...@hotmail.com > wrote:
> My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
> (based on shot performance and espresso flavor) and when I posed
> questions to others in different coffee forums the general consensus I
> received was that the OPV wasn't adjustable and was only there to
> safeguard the pump in the event of total flow restriction. I saw a
> screw in mine and I did turn it back out as far as it would go but I
> didn't notice any affect.
>
> I really don't think the Gaggias are very user adjustable and that's a
> shame. Rancilio has just included an adjustable OPV on the new Silvia
> why can't Gaggia put one on their entry-level machines? I think they
> would sell more machines and overcome one of the more problematic
> issues with their machines as you have noticed.

An adjustable pressure regulator is a serious piece of engineering.
Such valves are sold 25 to 200 USD. Cheaper doesn't work at all.
Silvia's new valve is around 40 USD. It means 5 to 10% with respect to
machine's price. Another point is how to mount that valve. It's not
possible to attach it to the pump due to it's high weight. Silvia is
using a tricky design to just fix it in an existing hole of the
boiler. I guess there is no such suitable place at the Gaggia's small
boiler. A new boiler design would be needed: more cost.



 
Date: 05 Jul 2007 12:12:30
From: SJM
Subject: Re: OPV/PRV and the need to adjust them.
On Jul 5, 11:54 am, TimEggers <timegg...@hotmail.com > wrote:
> On Jul 5, 1:51 pm, SJM <cajamadimail-goo...@yahoo.com> wrote:
>
>
>
> > On Jul 5, 10:44 am, TimEggers <timegg...@hotmail.com> wrote:
>
> > > My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
> > > (based on shot performance and espresso flavor) and when I posed
> > > questions to others in different coffee forums the general consensus I
> > > received was that the OPV wasn't adjustable and was only there to
> > > safeguard the pump in the event of total flow restriction. I saw a
> > > screw in mine and I did turn it back out as far as it would go but I
> > > didn't notice any affect.
>
> > > I really don't think the Gaggias are very user adjustable and that's a
> > > shame. Rancilio has just included an adjustable OPV on the new Silvia
> > > why can't Gaggia put one on their entry-level machines? I think they
> > > would sell more machines and overcome one of the more problematic
> > > issues with their machines as you have noticed.
>
> > I, on the other hand, turned a screw in the valve of my Gaggia Coffee
> > and got an incredible improvement in the quality of my shots. I have
> > spent 2+ years working on different roasts, different grinds,
> > different coffees, and one 180-degree turn of a hidden screw made
> > everything better.
>
> > SJM
>
> Very interesting indeed!

Still not perfect, and having just now ordered a liquid filled
pressure gauge, I can't tell you for sure what the current pressure
is, but my shots are definitely very tasty, whereas before they really
needed the camouflage of milk...

SJM



 
Date: 05 Jul 2007 11:54:19
From: TimEggers
Subject: Re: OPV/PRV and the need to adjust them.
On Jul 5, 1:51 pm, SJM <cajamadimail-goo...@yahoo.com > wrote:
> On Jul 5, 10:44 am, TimEggers <timegg...@hotmail.com> wrote:
>
> > My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
> > (based on shot performance and espresso flavor) and when I posed
> > questions to others in different coffee forums the general consensus I
> > received was that the OPV wasn't adjustable and was only there to
> > safeguard the pump in the event of total flow restriction. I saw a
> > screw in mine and I did turn it back out as far as it would go but I
> > didn't notice any affect.
>
> > I really don't think the Gaggias are very user adjustable and that's a
> > shame. Rancilio has just included an adjustable OPV on the new Silvia
> > why can't Gaggia put one on their entry-level machines? I think they
> > would sell more machines and overcome one of the more problematic
> > issues with their machines as you have noticed.
>
> I, on the other hand, turned a screw in the valve of my Gaggia Coffee
> and got an incredible improvement in the quality of my shots. I have
> spent 2+ years working on different roasts, different grinds,
> different coffees, and one 180-degree turn of a hidden screw made
> everything better.
>
> SJM

Very interesting indeed!



  
Date: 05 Jul 2007 15:09:22
From: Craig Andrews
Subject: Re: OPV/PRV and the need to adjust them.

"TimEggers" <timeggers@hotmail.com > wrote in message
news:1183661659.686214.301310@n2g2000hse.googlegroups.com...
> On Jul 5, 1:51 pm, SJM <cajamadimail-goo...@yahoo.com> wrote:
>> On Jul 5, 10:44 am, TimEggers <timegg...@hotmail.com> wrote:
>>
>> > My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
>> > (based on shot performance and espresso flavor) and when I posed
>> > questions to others in different coffee forums the general consensus I
>> > received was that the OPV wasn't adjustable and was only there to
>> > safeguard the pump in the event of total flow restriction. I saw a
>> > screw in mine and I did turn it back out as far as it would go but I
>> > didn't notice any affect.
>>
>> > I really don't think the Gaggias are very user adjustable and that's a
>> > shame. Rancilio has just included an adjustable OPV on the new Silvia
>> > why can't Gaggia put one on their entry-level machines? I think they
>> > would sell more machines and overcome one of the more problematic
>> > issues with their machines as you have noticed.
>>
>> I, on the other hand, turned a screw in the valve of my Gaggia Coffee
>> and got an incredible improvement in the quality of my shots. I have
>> spent 2+ years working on different roasts, different grinds,
>> different coffees, and one 180-degree turn of a hidden screw made
>> everything better.
>>
>> SJM
>
> Very interesting indeed!
>


To Sue, Tim, & Tex too. I've posted answers to this in different threads
with links & quotes talking about this quite a few months ago., & more
recently with Sue & Tex in the latest threads from a few days ago.. Also
with a link to a pdf showing 3 different OPV's & adjustments.
Here's the link!
http://myweb.tiscali.co.uk/coffeetime/userfiles/OPV_Valve.pdf

Tim, the Silvia had the new adjustable OPV from about 1995 I think it was.
Cheers,
Craig.




   
Date: 05 Jul 2007 16:45:13
From: EdT
Subject: Re: OPV/PRV and the need to adjust them.
Craig Andrews wrote:

> Tim, the Silvia had the new adjustable OPV from about 1995 I think it was.
> Cheers,
> Craig.
>
>
Craig.
Did you mean 2005? I don't think they were available in 1995.
Ed


    
Date: 05 Jul 2007 21:00:16
From: Craig Andrews
Subject: Re: OPV/PRV and the need to adjust them.

"EdT" <EdT@ornwart.net > wrote in message
news:468d9069$1@news.acsalaska.net...
> Craig Andrews wrote:
>
>> Tim, the Silvia had the new adjustable OPV from about 1995 I think it
>> was.
>> Cheers,
>> Craig.
> Craig.
> Did you mean 2005? I don't think they were available in 1995.
> Ed

Hey Ed, yep that's what I meant.., had a brain fart I guess! LOL!! {;-D
Cheers!
Craig.




   
Date: 05 Jul 2007 15:13:30
From: Craig Andrews
Subject: Re: OPV/PRV and the need to adjust them.

"Craig Andrews" <alt.coffee@deletethis.rogers.com > wrote in message
news:5f4tv2F397o5vU1@mid.individual.net...
>
> "TimEggers" <timeggers@hotmail.com> wrote in message
> news:1183661659.686214.301310@n2g2000hse.googlegroups.com...
>> On Jul 5, 1:51 pm, SJM <cajamadimail-goo...@yahoo.com> wrote:
>>> On Jul 5, 10:44 am, TimEggers <timegg...@hotmail.com> wrote:
>>>
>>> > My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
>>> > (based on shot performance and espresso flavor) and when I posed
>>> > questions to others in different coffee forums the general consensus I
>>> > received was that the OPV wasn't adjustable and was only there to
>>> > safeguard the pump in the event of total flow restriction. I saw a
>>> > screw in mine and I did turn it back out as far as it would go but I
>>> > didn't notice any affect.
>>>
>>> > I really don't think the Gaggias are very user adjustable and that's a
>>> > shame. Rancilio has just included an adjustable OPV on the new Silvia
>>> > why can't Gaggia put one on their entry-level machines? I think they
>>> > would sell more machines and overcome one of the more problematic
>>> > issues with their machines as you have noticed.
>>>
>>> I, on the other hand, turned a screw in the valve of my Gaggia Coffee
>>> and got an incredible improvement in the quality of my shots. I have
>>> spent 2+ years working on different roasts, different grinds,
>>> different coffees, and one 180-degree turn of a hidden screw made
>>> everything better.
>>>
>>> SJM
>>
>> Very interesting indeed!
>>
>
>
> To Sue, Tim, & Tex too. I've posted answers to this in different threads
> with links & quotes talking about this quite a few months ago., & more
> recently with Sue & Tex in the latest threads from a few days ago.. Also
> with a link to a pdf showing 3 different OPV's & adjustments.
> Here's the link!
> http://myweb.tiscali.co.uk/coffeetime/userfiles/OPV_Valve.pdf
>
> Tim, the Silvia had the new adjustable OPV from about 1995 I think it was.
> Cheers,
> Craig.
>

P.S. I'd also suggest perusing the Home Barista forums for more technical &
civil answers. http://www.home-barista.com/forums/
Craig.




 
Date: 05 Jul 2007 11:51:38
From: SJM
Subject: Re: OPV/PRV and the need to adjust them.
On Jul 5, 10:44 am, TimEggers <timegg...@hotmail.com > wrote:
> My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
> (based on shot performance and espresso flavor) and when I posed
> questions to others in different coffee forums the general consensus I
> received was that the OPV wasn't adjustable and was only there to
> safeguard the pump in the event of total flow restriction. I saw a
> screw in mine and I did turn it back out as far as it would go but I
> didn't notice any affect.
>
> I really don't think the Gaggias are very user adjustable and that's a
> shame. Rancilio has just included an adjustable OPV on the new Silvia
> why can't Gaggia put one on their entry-level machines? I think they
> would sell more machines and overcome one of the more problematic
> issues with their machines as you have noticed.

I, on the other hand, turned a screw in the valve of my Gaggia Coffee
and got an incredible improvement in the quality of my shots. I have
spent 2+ years working on different roasts, different grinds,
different coffees, and one 180-degree turn of a hidden screw made
everything better.

SJM



 
Date: 05 Jul 2007 10:44:09
From: TimEggers
Subject: Re: OPV/PRV and the need to adjust them.
My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
(based on shot performance and espresso flavor) and when I posed
questions to others in different coffee forums the general consensus I
received was that the OPV wasn't adjustable and was only there to
safeguard the pump in the event of total flow restriction. I saw a
screw in mine and I did turn it back out as far as it would go but I
didn't notice any affect.

I really don't think the Gaggias are very user adjustable and that's a
shame. Rancilio has just included an adjustable OPV on the new Silvia
why can't Gaggia put one on their entry-level machines? I think they
would sell more machines and overcome one of the more problematic
issues with their machines as you have noticed.




  
Date: 06 Jul 2007 16:18:24
From: daveb
Subject: Re: OPV/PRV and the need to adjust them.??

> why can't Gaggia put one on their entry-level machines?

ONE REASON -- COST.

DAVE
www.hitechespresso.com


I think they
> would sell more machines and overcome one of the more problematic
> issues with their machines as you have noticed.
>



  
Date: 05 Jul 2007 19:14:26
From: Robert Harmon
Subject: Re: OPV/PRV and the need to adjust them.
Howdy Tim!
The OPV's (or safety valves as Gaggia refers to them) on Gaggia's without
three-way valves are located on the pumps. It's smaller than most such
valves and I can't swear as to their efficiency, but the design is similar
to all other OPV/PRV's - piston, spring, o-ring or pea-valve, and threaded
adjustment.

One problem is directly related to their placement - it's not in path of
descaling solution so it tends to get sorta funky (gratuitous use of
technical terminology). Using a blank filter will force the OPV open & route
descaling solution through it, but this presents a risk for the pump so I
don't recommend it. A better idea is to remove the valve & disassemble it
for a thorough cleaning once in a while.
--
Robert Harmon
--
http://www.tinyurl.com/mb4uj - My coffee pages.

http://www.tinyurl.com/2tnv87 - My 'Guidelines For Newbies' page.

http://www.tinyurl.com/2cr3e2 - I have things for sale here.
"TimEggers" <timeggers@hotmail.com > wrote in message
news:1183657449.635971.162870@n2g2000hse.googlegroups.com...
> My Gaggia Coffee Deluxe brewed at what I felt was very high pressures
> (based on shot performance and espresso flavor) and when I posed
> questions to others in different coffee forums the general consensus I
> received was that the OPV wasn't adjustable and was only there to
> safeguard the pump in the event of total flow restriction. I saw a
> screw in mine and I did turn it back out as far as it would go but I
> didn't notice any affect.
>
> I really don't think the Gaggias are very user adjustable and that's a
> shame. Rancilio has just included an adjustable OPV on the new Silvia
> why can't Gaggia put one on their entry-level machines? I think they
> would sell more machines and overcome one of the more problematic
> issues with their machines as you have noticed.
>
>




 
Date: 05 Jul 2007 05:55:41
From: jmol121-groups@yahoo.com
Subject: Re: OPV/PRV and the need to adjust them.
> CW;
>
> * fresh roasted beans are best if used within 1 - 2 weeks
>
> * espresso is best brewed ~130psi (9 bar) & at ~196F.
>
> * three things affect the flow of a shot
>
> 1) pump pressure
>
> 2) OPV/PRV setting
>
> 3) grind/dosing/tamping of beans
>
> If the pump passes a water debit test it's assumed to be functioning
> properly (most vibe pumps are capable of 14 - 17 bar). If the OPV/PRV is
> properly adjusted the brew pressure will be limited to ~9 bar, with the
> excess being redirected to the water reservoir. If the beans are freshly
> ground & of the proper degree of fineness, and are tamped consistently, the

> Fact;
>
> I tested seven Gaggia espresso machines brew/group pressure and all had the
> OPV/PRV adjustments wrong.


How can you state by FACT that the OPV/PRV are wrong, if you're basing
it on conventional wisdom that 9bar is correct?



 
Date: 05 Jul 2007 05:53:25
From: Allison Molinari
Subject: Re: OPV/PRV and the need to adjust them.
> * fresh roasted beans are best if used within 1 - 2 weeks
>
> * espresso is best brewed ~130psi (9 bar) & at ~196F.
>
> * three things affect the flow of a shot
>
> 1) pump pressure
>
> 2) OPV/PRV setting
>
> 3) grind/dosing/tamping of beans
>
> If the pump passes a water debit test it's assumed to be functioning
> properly (most vibe pumps are capable of 14 - 17 bar). If the OPV/PRV is
> properly adjusted the brew pressure will be limited to ~9 bar, with the
> excess being redirected to the water reservoir. If the beans are freshly
> ground & of the proper degree of fineness, and are tamped consistently, the
> resulting espresso shot will be 1.5 - 2 ozs in 25 - 30 seconds.

> Fact;
>
> I tested seven Gaggia espresso machines brew/group pressure and all had the
> OPV/PRV adjustments wrong.

How can you state by FACT that the OPV/PRV are wrong, if you're basing
it on conventional wisdom that 9bar is correct?