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  • Silvia OPV adjusting- worth doing!

    Bullitt and I have successfully adjusted our silvias to closer to 9 bars from around 11 or 12.
    Coffeeparts were absolutely marvelous in all this and quickly supplied the teflon gasket. I was wondering if I would actually be able to discern any difference in taste and I have.
    Im sure its not my imagination- the shot was a LOT sweeter.
    If you have a silvia and havent done this mod, you really should. :
    RH

  • #2
    Re: Silvia OPV adjusting- worth doing!

    Yes RH,

    Pulling shots at the "right" pressure definitely pays dividends and I guess the magic number of 9 Bars wasnt arrived at by accident either. Pressures significantly higher than this are guaranteed to degrade the quality of the shot..... will seem over-extracted(very bitter) and a slightly burned edge to the taste in my experience. Have also noticed that the crema is more plentiful, sweeter and persistent too.

    When I was trying to get the pressure adjusted correctly on the Mokita (it was initially too low), I over-compensated and ended up with the pressure around the 14 Bar region. Brews produced at this setting were much as I described above and not very pleasant. It also made it much more difficult to dial-in the correct grind setting too as the difference between a reasonable shot and one that was either significantly too quick or too slow, was less than a single step adjustment on the Rocky. Getting the OPV back to the 9 Bar benchmark made a hell of a difference all round, quality of the shots improved out of sight and the grind setting became less critical when dialling in for a new blend or new beans, etc.

    Cheers,
    Mal.

    Comment


    • #3
      Re: Silvia OPV adjusting- worth doing!

      Originally posted by rayzurhed link=1161407746/0#0 date=1161407746
      Bullitt and I have successfully adjusted our silvias to closer to 9 bars from around 11 or 12.
      Coffeeparts were absolutely marvelous in all this and quickly supplied the teflon gasket. I was wondering if I would actually be able to discern any difference in taste and I have.
      Im sure its not my imagination- the shot was a LOT sweeter.
      If you have a silvia and havent done this mod, you really should. :
      RH

      Great post - thanks. A few questions to help me when I tackle this on my bench machine:

      - Did you use a portafilter gauge to measure the pressure? Or something else?
      - Is it necessary to make any compensation for static pressure (pump deadheaded) versus flowing pressure?
      - Does your machine have the new adjustable OPV? (You mentioned a gasket, so Im guessing not)
      - How many washers/gaskets did it take?

      Thanks in advance.

      Jim

      Comment


      • #4
        Re: Silvia OPV adjusting- worth doing!

        Originally posted by jggall01 link=1161407746/0#2 date=1161464502
        Originally posted by rayzurhed link=1161407746/0#0 date=1161407746
        Bullitt and I have successfully adjusted our silvias to closer to 9 bars from around 11 or 12.
        Coffeeparts were absolutely marvelous in all this and quickly supplied the teflon gasket. I was wondering if I would actually be able to discern any difference in taste and I have.
        Im sure its not my imagination- the shot was a LOT sweeter.
        If you have a silvia and havent done this mod, you really should. :
        RH

        Great post - thanks. A few questions to help me when I tackle this on my bench machine:

        - Did you use a portafilter gauge to measure the pressure? Or something else?
        - Is it necessary to make any compensation for static pressure (pump deadheaded) versus flowing pressure?
        - Does your machine have the new adjustable OPV? (You mentioned a gasket, so Im guessing not)
        - How many washers/gaskets did it take?

        Thanks in advance.

        Jim
        Hi Jim, check which of the vibrating pumps you have- probably the ulka. I have the ulka EK and in my botticelli (big silvia really) it was a matter of measuring flow from OPV in 30 sec (from when water flowed)with blind filter in- 8 bars was 150ml 10 bars was 100ml. You can do a google search based on your pump and youll find coffeesnobs threads with your model
        Brett

        Comment


        • #5
          Re: Silvia OPV adjusting- worth doing!

          The Rancilio website has all the necessary computations and graphs to tell you what the pressure for any given pump is using flow as an indicator.

          I checked mine probably about a year or so ago, and it was spot on 9 bars --out of the factory.

          Appliance shops which boast that their $159 thermoblock
          coffee machine is 15 bars! are doing everyone a disservice.
          Fifteen bars is just the rated capacity of the ulka pump.... not the pressure at which it should operate to make good espresso.

          --Robusto

          Comment


          • #6
            Re: Silvia OPV adjusting- worth doing!

            Hi, Brett -

            I actually plan to use my spiffy new portafilter gauge.

            But I thought I heard or read somewhere that your gauge reading should be a little higher than what you want the coffee to experience. I assumed, if this is true, that head losses from the flowing water will drop the brew pressure a little (as opposed to the static condition with no flow going through the portafilter gauge when you make your reading).

            Jim

            Comment


            • #7
              Re: Silvia OPV adjusting- worth doing!

              When we had our training day in Hobart- Chris from talk coffee used the handheld guage to check and mine was maxing out on 12- 13 bars.
              coffeeparts sent me a white circular gasket made from teflon and we replaced the thin brass one with this one.
              So - no it isnt an adjustable one and I dont know if I should have left the brass one on- all I know is it is better than it was before and I am very happy ;D.
              I might do the calculations on flow rate and see how close I am now.
              Perhaps someone out there know whether I was supposed to leave the brass one on?

              Again this morning I sampled a doppio and it ts finish was extremely sweet!
              RH

              Comment


              • #8
                Re: Silvia OPV adjusting- worth doing!

                As much as this has been great information, I also think it should have come with a bit of a disclaimer. As I now have visions of inexperienced tinkerers out there fiddling with OPVs and stuffing up their machines whilst either out of warranty or under it.

                Please guys, be a little cautious here in your enthusiasm! Id hate to see Chris now being inundated with people thinking that they should do these mods to their machines when they probably dont really need to. You know the old adage, "kids dont try this at home." Well thats how I feel about this topic and I think that if you do want to do any modifications to your machine, please seek the advice of professionals first.

                I know you all have great information and stuff to share, but just remember that we are being read here by those who have very little experience with this sort of thing...and yes they are learning by reading but we dont want to scare them off just yet!

                I say all this with gentle affection for all of you! Please dont think I am flaming anyone... :-[

                Comment


                • #9
                  Re: Silvia OPV adjusting- worth doing!

                  Wise words Scoots,

                  Playing around with what is essentially a "Safety" device intended to protect the pump from over-pressure , must not be approached in a cavalier fashion. While lowering the pressure in the system will do no harm, the converse is fraught with risk to both owner and machine. The disclaimer posted by Scoots should be considered by all who think they want to "play around" with this component.... If you are not absolutely sure about what you are doing, engage the help of someone who does know or take your machine to a reputable coffee equipment technician to make the adjustment for you.

                  Mal.

                  Comment


                  • #10
                    Re: Silvia OPV adjusting- worth doing!

                    Originally posted by Mal link=1161407746/0#8 date=1161527125
                    While lowering the pressure in the system will do no harm
                    Thats not true. There are quite a few guys who have done the washer OPV mod that have reported that their OPV now dribbles a little bit of water back into the reservoir when on but not in use for a little bit of time. The complaint usually comes up when they PID their machine then get irritated that they cant walk up and pull a shot because they have to run the pump for a few seconds to refil the boiler and they want to wait for a stable temp. So just be careful if you have done the mod and have your machine on a timer.

                    Ive left my OPV stock because Im going to sell my silvia relatively soon to finance an upgrade. Otherwise, Id be all over the mod like a mule on a peach.

                    Cheers,

                    Luca

                    Comment


                    • #11
                      Re: Silvia OPV adjusting- worth doing!

                      Originally posted by luca link=1161407746/0#9 date=1161536130
                       Otherwise, Id be all over the mod like a mule on a peach.
                      I had no idea that Mules were particularly fond of peaches. :-?

                      Back OT. The stall pressure will usually be up to 1 bar higher than the brewing pressure. So if you use a pressure measuring PF, then a setting of between 9 and 10 bar will get you around 8-9.5 bar depending on the flow rate. For example my Faema family (a 300 ml boiler similar to Silvia) will brew a single at close to 9 bar and a double at 8.5 bar. The OPV is set at a stall pressure of 9.25 bar.

                      Cheers,

                      Mark.

                      Comment


                      • #12
                        Re: Silvia OPV adjusting- worth doing!

                        Originally posted by luca link=1161407746/0#9 date=1161536130
                        Thats not true. There are quite a few guys who have done the washer OPV mod that have reported that their OPV now dribbles a little bit of water back into the reservoir when on but not in use for a little bit of time. The complaint usually comes up when they PID their machine then get irritated that they cant walk up and pull a shot because they have to run the pump for a few seconds to refil the boiler and they want to wait for a stable temp.
                        Hmmm,

                        Very interesting Luca. For this to occur the OPV would have to be adjusted to a point that is below the steam pressure while the boiler is under control of the Brew T/stat or PID setpoint.... It boggles the mind as to how low these particular individuals must have set the OPV.

                        As I mentioned above, my Mokita was set too low at around 7 Bar. No signs of the OPV bypassing at this pressure but the shot quality was abysmal. I cant imagine what the shot quality would be like with the the OPV set lower than this . And, at this low setting the OPV did NOT bypass continually into the reservoir, even when steaming. For this to occur, the OPV would have to be set down to about 3 Bar or less so it is a wonder that these people were ever able to pull a shot of any description..... It certainly wouldnt resemble anything like an espresso,

                        Mal.

                        Comment


                        • #13
                          Re: Silvia OPV adjusting- worth doing!

                          I do appologise for attempting to sway anyone into messing with their machines.
                          If you intended to copy my experience by adding a gasket to reduce your pressure... Dont do it. You will probably void your warranty, and if thats not an issue then you might damage something. :-?
                          I hope I havent led anyone astray.
                          It is easy to make recommendations when you dont take any responsibility for the problems you create. :-/
                          Sincerely
                          RH- sipping on a sweeeeeeeet dopio. ;D

                          Comment


                          • #14
                            Re: Silvia OPV adjusting- worth doing!

                            I might just weigh in on this one too.
                            I actually did the modification to both units, and yes if youre not sure after reading the excellent how to posts, (Google "silvia pressure mod page" for an excellent post with pics) then get someone who is confident to do it.
                            Personally I didnnt think it was beyond any home handyperson who understands how the machine is supposed to work, but then my background probably helps me there.

                            A word of caution about checking the alleged pressure based on OPV flow rate with a blind filter in...mine appeared to be OK, but I was always suspicious that it was pouring too fast even with very fine grind and updosing etc.
                            Proof was in the PF with pressure guage that 2mcm fitted when at the Hobart training day, mine was up around 11 bar.
                            Usual discalimer applies,
                            if not sure of what youre doing, consult your local Coffeesnobs preofessional.

                            And yeah I didnt know mules liked peaches either.

                            Regards
                            Bullitt

                            Comment


                            • #15
                              Re: Silvia OPV adjusting- worth doing!

                              One other thing I would like to add, is that we also should remember that Silvia is more than capable of producing quite decent coffee without having any modifications done to it. I know that with my machine I do nothing other than a poor attempt at temp surfing and I get results that still beat my efforts at work. Of course, it does also help that I purchase top quality coffee beans for home!

                              What Id like I guess is that potential new owners of a Rancilio who read this thread and others on the Silvia are made aware that they arent purchasing some scary machine that is difficult to use. Rather that they be aware that the guys here are searching for their "God Shots" and that modifying this machine is one way that they can reach that goal. And if theyre game enough to join you all on the journey, more power to them I say!

                              Comment

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