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  • Isomac Tea not building pressure

    Hi,

    I have an Isomac Tea III cool touch. It worked fine for a few years (maybe around 4) anyway fairly recently it became very inconsistent and most of the time does not build up pressure when trying to pull a shot. I took it to a shop in Melbourne to get it fixed. In their first attempt they gave it a service ($220) including descaling and changing the pressure stat, and told me it was good as new. Unfortunately when I took it home and tested it, it still wasn't working. I called them up, and they said it must be the pump so they replaced it (they just charged for parts so it was $60). Unfortunately, this has not fixed the issue either. In fact it has gotten worse the pressure now rarely moves above 2 bar, so it is impossible to make a decent shot of coffee. It did use to go between 4 and 9 (as in it would work intermittently), when it started to fail.

    If any of the shops in Melbourne know how to fix these machines, please let me know?

    Thanks,
    Chris

  • #2
    There is 3 things you need to get correct pressure.
    1. water that is heating,
    2. No leaking of pressure/steam as it's heating.
    3. Relays clicking on and off to maintain the pressure and temperature.

    First is controlled by the heating element. Does yours heat?

    Second is controlled by the anti vac valve. It will hiss a bit till the boiler heats, then seal off and start building pressure. Does yours hiss a bit, then stop as the boiler boils?

    Third is controlled by the pressurestat, your machine should click off as it reaches pressure, and click the heating element back on as it cools. Does yours cycle the element on and off?

    Comment


    • #3
      Thanks for the reply,

      The machine does heat up. It doesn't seem to have any trouble boiling the water.

      I don't hear any hissing when it is heating up. The steam wand hisses when I put it on, but I am not sure there pressure is as violent as normal. I only make a milk coffee every few months so I can't remember exactly how strong it should be.

      The pressurestat was replaced when I first put it into be fixed, so unless the replacement is also faulty it can't be that. The heat does turn off and on.

      Does this mean the anti vac value needs replacing? The drop off in performance has not been linear, in that pressure has been dropping off gradually, but not evenly, some days it worked better than others, although at the moment it won't even budge over 2 bars so it is completely stuffed now.

      Comment


      • #4
        Sounds like your machine is working as it should. Are you able to measure the actual pressure in the boiler? This will tell you if the boiler pressure is where it should be, usually around 1.2 bar.

        Perhaps your steam valve/wand/tip is blocked reducing the steam output? This seems more likely if it was a gradual decrease over time.

        Cheers

        Comment


        • #5
          So googling the tea 3, reveals a hx machine with a brew and boiler gauge. I see now after rereading your post you are referring to the brew pressure.
          I detailed how the steam pressure in the boiler is maintained and you are suggesting that it is ok and not leaking. And as artman suggested, the pressure you should be seeing on the boiler pressure gauge. If this is fine, any problem with steam will be an instruction in the steam path.

          Ok, brew pressure...
          What pressure do you get if you put your blind portafilter in and run the brew?
          What flow do you get if you remove the shower screens and measure how much water the pump flows in 30sec?

          How old are your beans, what grinder?

          Comment


          • #6
            Thanks again for the information. The steam is probably fine, it is the brew pressure that is down, it was always in the 9-11 bar range before, now it is 2 or less. I cannot even properly backflush the machine now it is so weak.

            The beans are less than a month old.

            I have a compac K3 grinder

            After removing the showerscreen 60ml in 30 seconds.

            After putting it back on I got 30ml in 30 seconds (not sure if it is getting even worse)

            The pressure gauge does not seem to budge at all now with the blind filter on, so below 1 bar.

            Comment


            • #7
              A suitably qualified tech that was aware of the 240v at the pump, element, solonoids and other spots, would now need to go into the machine.
              It's either the opv is bypassing too much water, or there is some pump problem.

              Opv.
              He should be able to look and see if 300ml/30sec is going out the opv bypass line. Normally the opv is after the pump, and a water line feeds back in before the pump.

              Hmm, there is a few ways to proceed. Maybe spin the opv in a turn or 2, and see if that lifts the pressure.
              You could put a pipe on the opv bypass line, and install the blind and see if all the 300ml of water is going out the bypass line.

              There maybe some detrius in the opv, holding it open- easy to disassemble and clean (noting turns on adjuster for reassembly.

              He would need to measure pump flow at the pump. If it is good flow there, you need to check flow before and after the brew solenoid.

              Comment


              • #8
                Originally posted by Jackster View Post
                A suitably qualified tech that was aware of the 240v at the pump, element, solonoids and other spots, would now need to go into the machine.
                It's either the opv is bypassing too much water, or there is some pump problem.

                Opv.
                He should be able to look and see if 300ml/30sec is going out the opv bypass line. Normally the opv is after the pump, and a water line feeds back in before the pump.

                Hmm, there is a few ways to proceed. Maybe spin the opv in a turn or 2, and see if that lifts the pressure.
                You could put a pipe on the opv bypass line, and install the blind and see if all the 300ml of water is going out the bypass line.

                There maybe some detrius in the opv, holding it open- easy to disassemble and clean (noting turns on adjuster for reassembly.

                He would need to measure pump flow at the pump. If it is good flow there, you need to check flow before and after the brew solenoid.
                Thanks Jackster.

                Can anybody recommend a tech (self recommendations are fine) in Melbourne (Eastern Suburbs) that is qualified to do this?

                Thanks,
                Chris.

                Comment


                • #9
                  Chris from Talk Coffee at Northcote is well respected in the industry.

                  13/148 Arthurton Rd, Northcote VIC 3070
                  0401 679 478

                  Comment


                  • #10
                    Originally posted by Yelta View Post
                    Chris from Talk Coffee at Northcote is well respected in the industry.

                    13/148 Arthurton Rd, Northcote VIC 3070
                    0401 679 478
                    Fantastic, I will give him a call during the week.

                    Regards,
                    Chris.

                    Comment


                    • #11
                      Opv is my guess!
                      If he is replacing it, can I put up my hand for the old one?

                      Comment


                      • #12
                        Originally posted by Jackster View Post
                        Opv is my guess!
                        If he is replacing it, can I put up my hand for the old one?
                        Sure!

                        I will report progress on this thread.

                        Comment


                        • #13
                          Just an update, I will post another one after I get it back and make a coffee. I finally got around to dropping off the machine at Talk Coffee today. Chris seemed confident that it will most likely be not difficult to fix, so I am feeling optimistic that my machine will be revived.

                          Comment


                          • #14
                            So I got the report on the machine yesterday, and will pick it up tomorrow. From the report

                            We found previous service had been performed to a very poor standard. Inspected pump and
                            replaced anti-cavitation valve. Resolved outstanding service issues: Disassembled, serviced,
                            lubricated and replaced parts as required in the valves, wands and group of your espresso machine.
                            Completed pressure and electrical check and cleaned machine.

                            So Jackster no opv in the report (at least I am assuming as I have no idea what all of the different parts are). I am feeling confident that the machine is fixed this time (last time the other guys assured me that it was as good as new, so I guess I cannot be 100% certain until I try) so i bought fresh beans today as well, and can't wait to have a proper coffee machine back at my home.

                            Comment


                            • #15
                              I think you can trust what Chris@TC tells you mate...

                              Mal.

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