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Thread: What causes wet steam in a SBDU machine?

  1. #1
    Senior Member Dragunov21's Avatar
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    What causes wet steam in a SBDU machine?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I'm trying to work through teething problems with a PID'd Alexia (similar to the Isomac Zaffiro or VBM Piccolo) and here's the latest; wet steam (we're talking ~45ml of water in 15 seconds following the initial wand purge).

    What are the possible causes? My immediate thought was that the boiler was too full and the boiling water was splashing up into the steam takeoff pipe, but this occurs even after I've only primed through the group (with the takeoff 2/3 of the way down the boiler).

    What gives?

    *EDIT* I tried to show how much in the video but it just blew out of the shotglass, so ignore that bit.


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    Senior Member Dragunov21's Avatar
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    Bump for the move.

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    Very typical of single boiler machines. Simple purge is the only way to go.

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    Quote Originally Posted by Renegade View Post
    Very typical of single boiler machines. Simple purge is the only way to go.

    i'll try and measure up how much comes out of my silvia the next time i steam milk, but doesnt seem like its anywhere near as much as 40mls.


    im sure you've already considered it but any chance it could be a problem with scale build up?
    not sure what mechanism boilers fill by, but either scale build up on the steam intake from inside the boiler making it dip a little deeper than it should or some water level sensor issue?
    another possibility is just condensation on long piping.

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    Senior Member Dragunov21's Avatar
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    Quote Originally Posted by Renegade View Post
    Very typical of single boiler machines. Simple purge is the only way to go.
    Could you elaborate on "simple purge"? The only way I can get dry steam is to let it hit the high limit with the tap on the whole time (blasting out water the whole time and making a godawful mess), then turning off the tap when the element kicks back in and waiting for pressure to build then.

    Quote Originally Posted by timdimdom View Post
    i'll try and measure up how much comes out of my silvia the next time i steam milk, but doesnt seem like its anywhere near as much as 40mls.


    im sure you've already considered it but any chance it could be a problem with scale build up?
    not sure what mechanism boilers fill by, but either scale build up on the steam intake from inside the boiler making it dip a little deeper than it should or some water level sensor issue?
    another possibility is just condensation on long piping.
    Brand new machine, so not scale. Boiler is manual-fill; I've emptied the boiler and re-primed only using the group (rather than the steam tap) which should fill the boiler to about 2/3 rather than topping it off, as the group take-off point is 2/3 of the way up the boiler. Somehow it still managed to spit water forever.

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    What temp/pressure does it reach?

    Doesn't sound like condensation, as you say its effectively continuous, and the volume is too great.

    Could it be that when you initially fill the boiler, you are over filling it and flooding the steam line? Or does priming it avoid that (I have an auto fill HX, so no priming).

    If you open the steam tap until all of the water is through, and then wait for the pressure to build up again, does it happen again?

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    Senior Member chokkidog's Avatar
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    Is it a cool touch? If so, have you tried removing the teflon?

    The Alexia's steam wand doubles as the hot water dispenser when the machine is in brew mode.

    You're obviously not pouring a shot in the video but might there be an issue with this function?

    What is the standard actual volume of water % in relation to total boiler volume?

    If your boiler is full when you pull the shot are you dumping some water to allow adequate headspace for the steam?

    Switch to HW dipense, dump 100ml (or more, progressively) til the seam is running dry.

    This is most likely your issue.
    Last edited by chokkidog; 5th May 2014 at 10:47 AM. Reason: punctuation

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    Senior Member Dragunov21's Avatar
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    Quote Originally Posted by MrJack View Post
    What temp/pressure does it reach?

    110C when I start, hi-limit cuts out at 121C

    Doesn't sound like condensation, as you say its effectively continuous, and the volume is too great.

    Could it be that when you initially fill the boiler, you are over filling it and flooding the steam line? Or does priming it avoid that (I have an auto fill HX, so no priming).

    Yes, the steam line will be flooded, as I prime the boiler through it until water flows after steaming.

    If you open the steam tap until all of the water is through, and then wait for the pressure to build up again, does it happen again?

    If I open the steam tap and let it spit everywhere for 30-60sec, then close it once the element kicks back in, then the steam is dry, but this brings the total waiting time for steam to something like 2-2.5 minutes, which I imagine is abnormal (especially since leaving the sputtering tap open makes a massive mess).
    Quote Originally Posted by chokkidog View Post
    Is it a cool touch?
    Negative

    The Alexia's steam wand doubles as the hot water dispenser when the machine is in brew mode.
    Yep. Open tap + prime/pump switch pumps water into the boiler from the resevoir. When the boiler is full you'll get a stream of water from the steam tap.

    You're obviously not pouring a shot in the video but might there be an issue with this function?
    Nope, pretty simple system (as above).

    What is the standard actual volume of water % in relation to total boiler volume?
    What do you mean by this?

    If your boiler is full when you pull the shot are you dumping some water to allow adequate headspace for the steam?
    The only way to force water out of the boiler is by pumping more in. (Is this not the case with all SBDUs?)

    Switch to HW dipense, dump 100ml (or more, progressively) til the seam is running dry.
    If I do this, it will just fill any space in the boiler with water as the hot-water/steam takeoff is at the very top of the boiler, won't it?

    This is most likely your issue.
    Chokki, am I misunderstanding what you're saying or just being thick? :S

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    Was just on the Chris' Coffee site looking at this machine when a customer rep popped up in chat asking if they could help. I remembered this thread so asked her what might be the case.

    Basically what the others said:

    Me: "it continues to spray a lot of water for 30-60 seconds after the purge. once the element turns on and pressure is back up, steam will be fine
    Rep: "Yeah it will take about that long to get the water out, because the boiler was filled with water. In order to get rid of that water inside you need to open the steam valve to lower the water level allowing room for steam"

    Being a manual fill it would be easy to overfill it. Also, not being autofill, you could drain the boiler and it still wont fill up with water until you tell it to. Not sure why on a $1500 machine they didn't include an autofill system, I guess they had their reasons.

  10. #10
    Senior Member Dragunov21's Avatar
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    Yeah, I've been chatting to the (very patient) guys in the tech department and I suspect I may just be being impatient because the heat>purge>wait>heat>steam routine wasn't an issue on my last machine (Gaggia Classic).

    The biggest problem, honestly, isn't the wait, it's the fact that the two-hole steam tip sprays water all over the place during the purge if the tip has rotated on the arm (during cleaning or what have you). Not a dealbreaker, just an ergonomic PITA

    I suppose I could get a 600ml jug to purge the wand into (it just blows water out of the spare 300ml jug I have), but I'm thinking of just getting a 1-hole tip for it instead.

    One thing I'm still confused by is you/chokki talking about draining the boiler; as I understand it the path runs tank>pump>OPV>boiler>group, so the only way to force water out of the tank is by forcing cold water in from the reservoir, no? It doesn't really need an autofill as unless you're steaming a litre of milk in between shots there's no risk of it running dry.

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    I'm having the exact same issue as the OP, but with the updated version of the Alexia (Evo model). I wonder if this is a unique issue to Quick Mill, or a general problem with SBDU? In any case, if there's any solution I'd be very happy to learn about it :-)

    Thanks!

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    I know what you're saying about the Gaggia Classic refill, but it's not really missed despite that, I had a laugh!
    Have moved on to a VBM Piccolo and although the refill procedure sounds the same as for Alexia, the water/steam pipe issue experienced with the Alexia is not shared with my VBM.
    Its just a simple purge of around 20-30 mls (guestimate) before steaming, turnaround about a minute to steaming from shot pull.
    Perhaps as you say, it's a design idiosyncrasy of this machine?



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