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Giotto PP Problem - boiler safety valve

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  • Giotto PP Problem - boiler safety valve

    Long time lurker, first time poster.
    I have owned a Rocket Giotto PP for about 5 years, used daily and backflushed weekly.
    This week the machine has experienced a problem, the machine heats up normally and maintains ordinary boiler pressure. When a shot is pulled the extraction starts normally (perhaps a touch slower than usual) however after about 10 seconds the boiler pressure escalates suddenly (as indicated on the front pressure gauge) - and then the boiler safety valve kicks in and exhausts the pressure (as it should in this circumstance I guess).
    I have taken the sides off the machine and cleaned/descaled the water level probe, I didn't expect this to fix the problem however I knew this was a potential area requiring attention and figured may as well clean it up.
    Does this behaviour point to a particular issue? Any help appreciated.

  • #2
    Originally posted by clio64 View Post
    Long time lurker, first time poster.
    I have owned a Rocket Giotto PP for about 5 years, used daily and backflushed weekly.
    This week the machine has experienced a problem, the machine heats up normally and maintains ordinary boiler pressure. When a shot is pulled the extraction starts normally (perhaps a touch slower than usual) however after about 10 seconds the boiler pressure escalates suddenly (as indicated on the front pressure gauge) - and then the boiler safety valve kicks in and exhausts the pressure (as it should in this circumstance I guess).
    I have taken the sides off the machine and cleaned/descaled the water level probe, I didn't expect this to fix the problem however I knew this was a potential area requiring attention and figured may as well clean it up.
    Does this behaviour point to a particular issue? Any help appreciated.
    Sounds like the Pstat is playing up.

    Comment


    • #3
      Does this happen everytime you start brewing only? Or does the safety valve open with machine sitting idle also?

      If it is during brewing, sounds like your pump is not only providing water to the brew path, but also filling the boiler with pressure, that would be my guess.

      If your pstat cycles normally while idle (which you should hear) then it is functioning ok, althought it could occasionally stay on and overpressure the boiler.

      Cheers


      Cheers

      Comment


      • #4
        Hi clio64,

        I have just experienced the same issue that yoi have described, along with water coming out (spurting) from the vaccum breaker valve during heating. Pressure at temp is good (1.1 - 1.3 bar) but as soon as I go to pull a shot the pressure spikes to 2+ bar then hovers at 1.5bar due to the boiler relief valve (even without portafilter fitted). I had the machine serviced about 4 months ago (new seals including group resealed) and valves (vacuum & boiler relief), so I wasn't expecting this sort of thing to happen. What did you find was the problem with your machine, as mine also appears to have a reduced flow from the group (without the portafilter fitted)?

        Comment


        • #5
          I missed this thread.

          Some release of water (mainly vapour) during heating is normal. The release of any significant quantity of water is abnormal and can be dangerous.

          This can occur due to a number of factors. The most likely include:
          • boiler probe scaled or otherwise fouled. We have seen some where the teflon cover on the probe has not been trimmed. As a result the probe cannot be earthed and an overfill occurs. Approx. 5mm of clean metal should be visible.
          • water has little or no ionic or solid content. Boiler probe is never earthed by the water and the boiler overfills as a result.
          • grotty or failing boiler solenoid directs some water to the boiler during each shot instead of sending it all to the group. A progressive overfill occurs.

          All issues are pretty easy to rectify but if you don't know what you're doing, find a good tech or someone else who does.

          Cheers

          Chris

          Comment


          • #6
            I know what you mean wrt to water vapour. Our machine has done that since day 1, but since yesterday it now spits water out of the vacuum breaker valve, and we have a crisis at home due to no good caffeine :-).

            I'll be calling a tech tomorrow in Geelong, Victoria for them to look at it.

            Do you have any recommendations fro the Geelong area?

            Comment


            • #7
              I would be getting in touch with site sponsor The Coffee Man (see link in the page footer), the workshop is in Nobility st. Moolap

              Comment


              • #8
                Originally posted by coffee_machinist View Post
                I would be getting in touch with site sponsor The Coffee Man (see link in the page footer), the workshop is in Nobility st. Moolap
                Thanks for the advice & reccomendation. They actually serviced my machine last, so hopefully there won't be too much too it (famous last words). I'll call them today once they open, as they were closed yesterday.

                Cheers

                Comment


                • #9
                  No worries. Happy to help....

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