Announcement

Collapse
No announcement yet.

O P Valve For Oscar Machine

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • O P Valve For Oscar Machine

    I now have had my Oscar for over 15 months and generally very happy with it. I thought the coffee could be a bit sweeter but I would not call it sour or bitter. I was informed that it is running at about 15 Bar pressure and not the desired 9/10 Bar. Is it worth fitting an OP Valve which would cost a few hundred $ -  or do you think it is not worth the trouble. I definitely dont wont to upgrade to one of the SS 000 machines. I just wanted advice about the OP Valve ,effectiveness etc.

    I know some of the sponsors do this work but what is the most cost effective way to do this - It would not be something that I could do myself.

    Thanks for your help.

  • #2
    Re: O P Valve For Oscar Machine

    How does the person that informed you know this? Did he/she fit a pressure gauge to the group. If not, he/she could be talking through his/her hat.

    The machine will already have some kind of bypass valve (yes thats what they are, not "over pressure" valves Im afraid) fitted otherwise the pump wold pump at its maximum rated pressure which could be anywhere between say 15 and  18 bars. So there is already a reduction to wherever the manufacturer deemed it should be set to at production, and I dont know if the current setup allows for any sort of adjustment.

    And for the rest of it, the machine works fine. If it is at wherever the manufacturer set it to, and its making coffee ok, dont let idle discussions in these forums set you off on an unnecessary mission.....because the question is, if you manage to measure the current set point, then reduce it to forum spec, will YOU notice any difference in anything, that can be solely attributed to your having changed the setting of the bypass valve?

    If she aint broke..................

    Example. There are probably tens of thousands of early Rancilio Silvia machines out there that were set to around 12 bars at production.  Everyones made a big song and dance about this in forums and the factory modified later models to the accepted nominal spec. which is somewhere between say 8 and 10 bars pressure.


    But there are still tens of thousands of early silvias out there working just fine as they are, apparently as are you with your oscar. If you are drinking predominantly milk coffees, do you think it will make any difference to your brews?

    Im sure others will have an opposing view

    Attilio
    very first CS site sponsor

    Comment


    • #3
      Re: O P Valve For Oscar Machine

      It is always a bit of gamble asking questions on a forum as the respondents make assumptions that are not always correct - however never mind.

      Originally posted by 142037213A0D113D34343737520 link=1336792049/1#1 date=1336794615
      How does the person that informed you know this? Did he/she fit a pressure gauge to the group. If not, he/she could be talking through his/her hat.The machine will already have some kind of bypass valve (yes thats what they are, not "over pressure" valves Im afraid) fitted otherwise the pump wold pump at its maximum rated pressure which could be anywhere between say 15 and  18 bars. So there is already a reduction to wherever the manufacturer deemed it should be set to at production, and I dont know if the current setup allows for any sort of adjustment.
      I didnt want to mention it but the infomation as to the Oscar was from a well  known Sponsor after testing the machine.  I was asking whether any others had an opinion as to the worth or otherwise of this modification.


      I am not sure whether I used the correct terminology but I was tryng to see if I with my machine I could get
      a richer or sweeter coffee and that was the reason for my question as to whether the modiification  was justified or whether the cost was not warranted for this type of machine.

      Comment


      • #4
        Re: O P Valve For Oscar Machine

        My opinion is also dont bother.

        There are great machines around in the FS section for amazing prices. Better to sell and move on if you can manage your fear of SS. Bottom line will be a superior machine and no money wasted on a mod which nobody will pay you for when you do sell it.

        Comment


        • #5
          Re: O P Valve For Oscar Machine

          I feel a little like Shirly Temple stepping in to the ring with Mike Tyson, but Im gonna disagree with you there Attilio, on 2 points:
          1) The Oscar has no factory built in Bypass valve. Its just doesnt exist. Weird I know, but its the truth. The closest is the HX loop safety vale attached to the group, and thats a 16bar valve according to the Oscar parts list. I dont know if it definitely opens at 16 bar or not, but it definitely opens at something over 13 bar, cause it didnt open when I attached Gregs gauge to my Oscar and it read 13 bar.
          2) The Oscar definitely improves with a bypass valve installed on the cold side of the pump line to regulate the brew pressure to ~9 bar. I know this cause Ive installed one on mine. Before the install my shots were always thin and weak. I think this is because the high pressure made the water really prone to channelling. But after the install the coffee was much easier to get right, was richer in flavor, thicker in mouth feel and the grind did not need to be as fine.

          I will agree with you that without a bypass valve the brew water would up around 15 bar though - cause when I tested the brew pressure with Gregs gauge and it read 13 bar, that was after I installed the bypass valve. So that means without the bypass valve installed the pump pressure would have been even higher than 13 bar. I couldnt test it with the bypass valve closed cause I couldnt tighten it up enough to make it not open and bypass some water pressure.

          Is it worth putting in? Well when I called a service place to ask for advice, they indicated it would be a difficult and long job to install - at least a couple of hundred in labour costs, so I did it myself. It was a pain in the a$$. If youre going to do it yourself, you like tinkering, you dont mind a bit of trial and error and you have lots of patience, then it is rewarding. Both in the coffee improvement and the sense of satisfaction of achievement. You have to enjoy tinkering otherwise it will be too frustrating. If youre going to pay someone to do it for you, i guess you have to figure out how much a well behaved Oscar is worth to you.

          To answer your question "what is the most cost effective way" - do it yourself. If you cant its going to be expensive, because after you install it it needs to be dialed in. It will also increase the brew temp cause theres less flow through the HX, increasing the temp. Do a search on HB, someone did some tests.

          Its a good machine, and becomes great with mods like OPV, flow restrictors, anti-vac, boiler gauge (and boiler dialed in). Im glad I did the mods myself but I wouldnt have paid someone else to do it.

          Comment


          • #6
            Re: O P Valve For Oscar Machine

            Happy to be corrected as and where someone has better expertise.

            A service provider would in 99% of scenarios most probably simply refuse to do the job so yes, I am afraid this really is within the realms of DIY or nothing. This is because most sevrice centres have their hands full already in servicing / repairing machines as standard and dont need to get involved in unknowns with modifications that can turn problematic in terms of cost VS owner expectation. Except....if the service centre happens to be the oscar service agent and can act fast and in sure footed manner with the model.

            So from the point of view of most service facilities, not worth doing no matter what the gain may be in the brew.

            Im with Chris on this one and unless the owner is looking for a project and is also prepared to be wthout his presumably main machine for an unknown period while he remanufactures it :..."There are great machines around in the FS section for amazing prices. Better to sell and move on......... Bottom line will be a superior machine and no money wasted on a mod which nobody will pay you for when you do sell it...."

            Re: "...Its a good machine, and becomes great with mods like OPV, flow restrictors, anti-vac, boiler gauge (and boiler dialed in). Im glad I did the mods myself but I wouldnt have paid someone else to do it...."

            Yes perfectly understood and the owner of such has probably calculated that he probably could have just cut to the chase and bought one of the SS offerings where it has already all been provided, and ends up with a much more saleable used machine at the end of it (as noted by Chris).   Oscar is built to a price point and that is its strenght which is, that its great for what it is. When you turn it into a more expensive SS machine with all that already provided, it still only has the plastic body and will still only be worth a used oscars value. But certainly it will have prvided hours of fun for a someone that finds projects a challenge.

            After all of that then, my opinion is still that the cost / trouble of any modding to this albeit quite good little machine really isnt justified.

            Comment

            Working...
            X