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  • Steamer causing excessive bubbles

    I have noticed something a bit odd with the profitec pro 800 last two days.I pour my shots and go to steam some milk.
    As normal I bleed any of the wet steam/condensate in the steam wand for maybe a second or two until it looks dry enough. Then cut it off, insert the steam wand in the milk jug and turn the knob back on to get the steam going. The last two mornings however a whole bunch of what looks like air bubbles have formed at the top of the milk jug. Almost like I got a straw and blew a few big bubbles in the jug. The milk looks more like bubble bath water - maybe the bubbles are a bit bigger than that, the size of a 5c piece?
    After maybe 2 seconds they seem to stop and the milk begins to swirl and froth as normal.

    Doesn't seem to affect the final outcome of the microfoam other than I have to work a little harder to make sure the big bubbles disperse and get mixed into the vortex. But I am a bit perplexed why this is happening all of a sudden?
    The same 3L milk I have been using for maybe 4 days to a week so shouldn't be that.

    It seems like there is excessive air in the boiler somehow. Anyone have any experiences similar or any reasonable guesses what is going on?

    Cheers,

    WEBN
  • Answer selected by Javaphile at 26 August 2022, 12:52 PM.

    Second update - Turned the machine on last night to investigate and as soon as the pressure gauge started to rise it shot up to well over pressure - like 2+bar. Purged the life out of the steam wand suspecting there might be excess air in the boiler and yup, that was the culprit. Gauge shot back down to approx 1.1 bar or normal levels.

    Discovered a small leak in coming form the lever group, so likely one or more of the piston seals have busted. Rubber ones tend to bake, become brittle and breakdown after so many heating/cooling cycles.

    Putting that all together what likely was happening is that as the machine cooled down excess air was being sucked into the boiler through the fine leak which mostly seemed to close up once up to temp. So I am guessing once the seals were warm they expanded enough to only leak a little bit. And while a small amount of air would probably escape during the first purge of the day for 1-2 seconds, there was significantly more in the boiler that needed to purge.

    Long story short, new seals to order/replace and the problem should resolve itself.

    Comment


    • #2
      If you have a a screw on steam tip it might be worth checking the o-ring/seal is still good inside the tip. If not, steam might be coming out there on the surface when not intended.

      I for a bit kept getting frustrated with less than ideal steaming when I didn't have a replacement o-ring for mine and I used a slightly larger o-ring until I received the proper size.

      Comment


      • WhatEverBeansNecessary
        WhatEverBeansNecessary commented
        Editing a comment
        Thanks Alistair will check that tonight.

        The only other suggestion that came up during a google was check there isn't any blockages in the steam tip as the 3 or 4 holes might be reduced down to 1 or 2 etc and causes higher pressure. But pretty onto cleaning so doubt it is that considering it's never blocked in the 4+ years of ownership.

      • AlastairMcG
        AlastairMcG commented
        Editing a comment
        Well at least you can check for blockage when taking the tip off to check the o-ring.

    • #3
      Update: Took off the steam wand, checked the o-ring, cleaned the wand and swapped the milk for a fresh batch.
      Same issue still persists.

      Little stumped now.

      Comment


      • #4
        Sounds like the same phenomenon I get with the Rocket Boxer 3gr at church if I don't purge enough steam before I use it for the first time since the machine heated up.

        I would suggest trying a longer purge and see if that fixes it. At least as long as until it stops doing it in the milk. The Boxer has a ~25L service boiler so I need to purge for 20-30s, but hopefully you won't need that long!

        Couldn't tell you why it changed, but my suspicion would be with the anti-vac valve.

        Comment


        • WhatEverBeansNecessary
          WhatEverBeansNecessary commented
          Editing a comment
          Thanks mate, will give that a go. Possibly very sticky anti vac valve let some air in. Will try a super long purge tomorrow morning and report the results.

      • #5
        Second update - Turned the machine on last night to investigate and as soon as the pressure gauge started to rise it shot up to well over pressure - like 2+bar. Purged the life out of the steam wand suspecting there might be excess air in the boiler and yup, that was the culprit. Gauge shot back down to approx 1.1 bar or normal levels.

        Discovered a small leak in coming form the lever group, so likely one or more of the piston seals have busted. Rubber ones tend to bake, become brittle and breakdown after so many heating/cooling cycles.

        Putting that all together what likely was happening is that as the machine cooled down excess air was being sucked into the boiler through the fine leak which mostly seemed to close up once up to temp. So I am guessing once the seals were warm they expanded enough to only leak a little bit. And while a small amount of air would probably escape during the first purge of the day for 1-2 seconds, there was significantly more in the boiler that needed to purge.

        Long story short, new seals to order/replace and the problem should resolve itself.

        Comment


        • #6
          I am having a similar problem. My Rocket R58 which I have had for about 6 years has made fine foam for all that time. In the last two weeks it makes a lot of noise and bubbles. The noise generated by the large bubbles interacting with the steam jet. There is no nice silky foam. I have cleaned the steam nozzle. I have replaced the steam nozzle (1.5 mm to 1.2 mm) - no improvement. The steam pressure remains high. I have changed the boiler water with fresh water. I have evacuated any water/air in the steam piping before steaming. There does not appear to be any steam seal leakage as the pressure remains high.
          I have tried steaming milk, full cream and reduced cream, Almond Milky.
          I am totally perplexed!
          🤔

          Comment


          • WhatEverBeansNecessary
            WhatEverBeansNecessary commented
            Editing a comment
            Only thing I can say is purge the hell out of the steam wand to get all the air out. I noticed that when it was heating the pressure gauge shot well over normal because the air would compress. First time I had to purge maybe for 20-30 seconds at least. Give that a go and purge for a minute or more and see.

            Failing that are you confident the pressure is regulating okay? A fault thermostat could cause excess pressure. But there would be a heap of other symptoms too like hotter water temp etc.

        • #7
          Thank you. I will give that a try. The big question is what has caused this after so long.

          Comment


          • #8
            Bit of a final roundup on this post for anyone who is interested.

            Finally got the new seals in after my parcel got lost in the mail and had to be resent.
            New seals + liberal application of Molykote 111 the leaking has completely stopped at the grouphead as suspected. I also 'invented' a new tool for getting the piston seals on a bit easier which I will post in a new thread to keep this one cleaner.

            Also took the top of the pro 800 off and found the anti-vac valve was stuck open as suggested by level3ninja
            So took that off, disassembled and cleaned/checked seals which were all still good. Didn't see anything visible causing it to stick. Once it was reassembled all the issues were gone. so I suspect the antivac valve wasn't letting the air escape as intended.

            Long story short its all back to working order and the brew has never tasted as good!

            Comment

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