tegee Senior Member Joined: 29 Feb 2012 Posts: 47 Location: New England Expertise: I love coffee
Espresso: Brewtus IV-R Grinder: Baratza Vario
Posted Sat Mar 3, 2012, 4:48pm Subject: Gaggia Classic.....Adjusting the OPV
Hello Everyone,
Kinda new to this forum and thank all that have help me so far with the purchase of my Gaggia Classic.
I would like to adjust my machine so its output is only 9 bars and need a little guidance.
1) I need to know if I should adjust by attaching to the portafilter or the steam wand? 2) Depending on which hookup, what fittings, etc I will need? 3) And lastly, what good video (youtube, etc.) do you suggest I watch to gain a better understanding on the components within the machine I need to adjust.
*Or do you know exactly how many clicks and/or turns of the settings screw I need to turn; instead of using the gauge approach???
I am very mechanically incline and don't mind getting inside the machine to perform the necessary adjustments. I just want to dot my 'i' and 't' so i do not break my new machine.
I did do extensive perusing of this site and did not find any good topics that covered it in my search.
Any help, links or good direction would be GREATLY appreciate.
Posted Sat Mar 3, 2012, 7:14pm Subject: Re: Gaggia Classic.....Adjusting the OPV
You definitely want to build a gauge for the adjust. Trying to turn it a set amount will just get you into trouble as the valve is EXTREMELY sensitive with even a slight turn. I experimented with that method then tested it with a gauge and it was way off. I made a gauge and have a pic, but I machined my portafilter into a bottomless so it's a little different from what you'll end up doing.
Posted Sat Mar 3, 2012, 11:01pm Subject: Re: Gaggia Classic.....Adjusting the OPV
A lot of posts suggest measuring the amount of water going back to the water tank when using a blind filter - but I don't trust that at all since every pump I've ever tested has flowed differently.
My pressure gauge is NOT pretty - but I found it easily at the hardware store (meant for measuring garden hose pressure) and was able to remove the gauge from the garden hose fitting and just needed one elbow adapter to connect it to the portafilter (as long as you have a threaded spout portafilter adn not one of those older ones with the two molded in spouts.)
Having a gauge will pay for itself if you have any curiosity at all -- after you set it you can test again in a month or two to see if it has changed - and you can see if you get the same pressure when the machine is cold as you do when it is all warmed up. And you may want to see how you like your shots at 8 bar or at 10 or at 11 bars.
You may decide you are interested in pre-infusion --- I put a resistor in series with my pump and a switch to bypass the resistor. I flip the switch and the pump gets much quieter for preinfusion - having the PF gauge lets me see that I'm cutting the rpessure down to about 4-5 bars with the resistor in there. I experiment starting my shot at the lower pressure for a few seconds and then to high pressure for the bulk of the shot and then back to low pressure for a couple of seconds before I end the pull. It's a lot of fun and having the gauge lets you experiment like that and see what pressure you are actually getting.
But in case you want to just experiment first - you take the four screws out on the top to lift the top off. disconnect the hose from the top of the OPV and unscrew the top (the nipple that hose was on) and you will see the adjuster with a hex hole for an allen wrench (I forget what size) - probably back it off (counterclockwise) about 3/4 of a turn. Mine has not been so finicky that I couldn't turn it back the same amount and get pretty much right back where I was.
My machines are older (they used stronger pumps I believe) and there is quite a lot of water trickling back to the tank when pulling a shot (more than is going into my cup - but I pull ristrettos)
SJM Senior Member Joined: 17 Nov 2004 Posts: 1,508 Location: CA Expertise: I love coffee
Posted Sun Mar 4, 2012, 9:16am Subject: Re: Gaggia Classic.....Adjusting the OPV
Teegee, this might be a good time for you to join the Gaggia Group at Yahoo. There are lots of members there who have Classics and who have been doing the various mods on them and who would be glad to share their experience.
This is not to suggest that AndyPanda's suggestions aren't good, just to give you another place to get input before or while you jump into the exciting world of Gaggia mods....
SJM Senior Member Joined: 17 Nov 2004 Posts: 1,508 Location: CA Expertise: I love coffee
Posted Sun Mar 4, 2012, 2:09pm Subject: Re: Gaggia Classic.....Adjusting the OPV
Yup and Nope. I used to loan mine out, but I got tired of the general hassle, or maybe I just got lazy.
In any case, it seems that most members have been able to source the parts for very little more (or maybe even less) that the cost of two way USPS priority shipping and insurance.
Probably I would reconsider if someone really really couldn't manage....but only via the GUG site.
tegee Senior Member Joined: 29 Feb 2012 Posts: 47 Location: New England Expertise: I love coffee
Espresso: Brewtus IV-R Grinder: Baratza Vario
Posted Mon Mar 5, 2012, 1:47pm Subject: Re: Gaggia Classic.....Adjusting the OPV
Thanks everyone....I am just now getting around to checking in on my OP.
I spoke to WLL today, where I bought the machine, and they did not recommend messing with the OPV. But after extensive homework perusing the internet I think I will in fact by the necessary fittings and gauge and set it to 9 bars.
To that end, I did see a youtube vid that suggested setting it slightly higher then 9 bars, in the 9.5 to 10 range, because of something to do about back pressure????? I can not remember exactly what he mentioned, but I do recall the higher sitting.
I am really excited about my new Classic and have been enjoying shots for over a week now. At $380 you really can not beat this great espresso machine that keeps chugging along year after year. I want a Rancilio V3, but just could not cough up the $1k for the machine and necessary grinder. For $597 I bought the classic and grinder all in.
Anyway......GREAT help with my original post and I will check back in when I get the gear to set the OPV.
Posted Mon Mar 5, 2012, 3:48pm Subject: Re: Gaggia Classic.....Adjusting the OPV
I posted a YouTube video but it was for a Gaggia without a 3-way solenoid valve - those behave very differently and the point I was attempting to prove was that the spring loaded valve those non-solenoid machine use affects the pressure. So if that is the video you saw - I was trying to demonstrate something that does not apply to you.
My understanding (I'm confident I'm right, but many people disagree with me) is that with the 3-way valve you simply set the pressure to 9 bars (unless you feel that your particular coffee blend or your particular taste prefers extraction at higher or lower pressure).
For machines without the 3-way, the brew pressure changes based on how fast your shot is flowing. (that was the point of my YouTube video --- if you pull a double you have lower brew pressure than when pulling a single) --- but on the Classic with the 3-way valve, you get exactly the pressure you set the OPV for whether pulling a ristretto or a lungo a single or a double etc. With the only caveat being that if your grind/dose is so loose that it never reaches 9 bars at all - then the OPV never comes into play.
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