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Rancilio S26 running off tank letting hot water back through inlet hose

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  • #16
    A few quick photos. Thanks for the replies so far guys. I have a lot more to consider now.

    Click image for larger version

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    Last edited by voicecoils; 1 November 2015, 06:17 PM.

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    • #17
      $10 from bunnings, in their plumbing section, inline so easy to fit, yes you do need one, everything will be OK then, please keep me posted.
      Cheers,
      Mick.

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      • #18
        Originally posted by sprezzatura View Post
        [ATTACH]10788[/ATTACH]

        Level probe is in the middle white connection with white or grey wire.
        Bottom left of the photo is a 2 way solaniod and valve , the hot water should not be returning back from the heat exchanger past that , you do not want that hot water getting to the pump and it sounds to e that Is whats happening.

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        • #19
          Another possibility is that your bypass in the vane pump is stuck. Machines that sit for awhile can have the little o ring in the bypass 'stick' so that most of the water bypasses and never reaches full pressure. Field techs like myself will unscrew the bypass and pull the assembly out, use a tiny amount of food grade silicone on the o ring and reassemble. Cycling the set screw several turns in (counting) and then back out may free the bypass as well. We use a portafilter with a gauge to confirm pressure (6 - 9.5 bar depending on several top secret roaster factors).

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          • #20
            Cleancup has a good point too. Your boiler fill solenoid may be fouled. Ensure there's a healthy 'click' (coil energised and mag field pulling nucleus plug up) and water flowing into boiler.

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            • #21
              Click image for larger version

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              Picked up a non return valve today which also has an isolating switch which is handy if disconnecting the tank.

              So far I've had the machine on for an hour running water through the group, hot water tap and steam wand without any issues at all. I'll provide and update if this changes.

              The fact that hot water was coming back through before is still a bit concerning and worth more investigation but I'm happy to have gotten to this point so I can actually try the machine out!

              Really impressed at the knowledge and helpfulness of you guys!

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              • #22
                Hi Voicecoils, where abouts did you purchase the non return valve? I've been chasing one like that, that will connect to the bottom of a container. Cheers

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                • #23
                  Originally posted by kyeba View Post
                  Hi Voicecoils, where abouts did you purchase the non return valve? I've been chasing one like that, that will connect to the bottom of a container. Cheers
                  Nefa 15mm DR Brass Female Non Return Isolation Valve | Bunnings Warehouse

                  For my water container I also needed a 20mm to 15mm male-to-male reducer plus some plumbers tape!

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                  • #24
                    Awesome, thanks mate

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                    • #25
                      voicecoils,
                      Great to know you have sorted the pump problem,hopefully your rotary pump is running nicely now and will continue to do so for your ongoing coffee enjoyment!
                      Still may be worth while following the mentioned suggestions of confirming the clearing/operation of your pump too.
                      Cheers,
                      Mick.
                      Click image for larger version

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                      Last edited by mulquemi; 2 November 2015, 11:42 AM.

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                      • #26
                        Nice easy fix! Cheers!

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                        • #27
                          Thanks again guys.

                          My next 2 tasks are to calibrate pump pressure once the Pullman portafilter gauge arrives and to service my grinder.

                          After that I'll work through the checklist for the S26 that everyone's given me so far:

                          * clean water level probe
                          * check function of OPV valve
                          * check function of check valve downstream of pump
                          * check level controller & wiring
                          * check that hot water is not returning back from heat exchanger past 2 way solanoid & valve
                          * check bypass in vane pump (calibrate pump pressure with gauge portafilter)
                          * check that boiler fill solenoid makes healthy click and works properly

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                          • #28
                            Pullman gauge arrived so now I have my next challenge: group head pressure is at 3.7 bar!

                            The adjuster screw on the procon makes no difference whether full in or wound full out.

                            I checked the gauge on my Silvia and it is still solid 9 bar where I set it at months ago.

                            Luckily I have a spare procon I can pull parts from or swap in. Fun for this weekend!

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                            • #29
                              A bit of success, but not quite there. I pulled apart the pressure adjustment mechanism on the procon in the S26. It actually was in great condition and far less crusty than my spare pump's parts.

                              I stretched the spring out a bit and reassembled. This time, adjusting the grub screw with the 19mm hex nut loosened I was able to raise the pressure close to 6 bar. Then I added a few spacers to put more force on the spring situated between the grub screw and spring. This got pressure up to 6 bar as pictured. Sadly I could get no higher. I'm not sure if more spacers will have much affect in raising the pressure if the bypass is fully closed off than that would be the max pressure the pump is capable of without mains pressure I would assume.

                              Also I noticed while working on the pump that hot water is still flowing back to it. I can't tell exactly what situation it happens in but the pump body became hot to the touch until I drew water from the hot water tap to force fresh cool water through the pump and cool it down. The anti return valve between the tank and pump is clearly working to keep hot water flowing back to the tank which *is* good to see.

                              Perhaps the old pump has been damaged by the heat of the hot water.


                              Click image for larger version

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                              Last edited by voicecoils; 7 November 2015, 08:09 PM.

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                              • #30
                                voicecoils,
                                Good to know you have the machine operating,despite your lower then expected delivery pressure....how does it go actually operating,good/great coffee?
                                I really believe the proofs in the delivered shot,fussing about whether its exactly 9 bar is neither here or there.
                                I try setting my machines close as possible and the resulting performance is never disappointing.
                                How did you go regarding following the list you set yourself?
                                I'd reckon your machine is pretty sorted by this stage.
                                Life's great with a operational coffee machine (or two).
                                Cheers,
                                mick.

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