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Thread: Help! No steam!! For a few minutes, anyway...

  1. #1
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    Help! No steam!! For a few minutes, anyway...

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Every now and then after my Futurmat turns on (it is on a 15 amp timer) and it has reached operating temperature (about 30 minutes) I find that it will not immmediately froth milk. This is the case from both steaming arms. The pressure gauge shows the usual optimal level but I only get a few seconds of half-hearted steam. Then nothing....

    The pressure in the boiler drops right down and the heating element cuts in. The heater stays on for a few minutes and the pressure gauge shows that boiler pressure is building up again. When the heater turns off, there is plenty of steam.....but it wasnt available there a few minutes before. This head of steam will be abundant anytime I use it while the machine is still turned on.....but it may or not be there next time it turns on....



    Has anyone else had this problem?

    Any ideas what I can do to get around this?

  2. #2
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    Re: Help! No steam!! For a few minutes, anyway...

    Paolo,

    The boiler is full of air!

    As the boiler cools down, the vacuum break valve opens (the steam in the boiler cools) and that sucks in air.

    When the timer turns on - the boiler heats up, the air expands, the vacuum break closes and the air in the boiler gets pressurised - but as soon as you open a wand, the pressure drops to zero.... the boiler eventually fills with steam....

    You could check your vacuum break valve - but at the professional machine course- we were told to open a steam wand when shutting down and leave it open until lots of steam is coming out at heat up ... but this is a little hard on a timer.

  3. #3
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    Re: Help! No steam!! For a few minutes, anyway...

    Sounds like you had air in your boiler instead of steam. You should open your steam wand when shutting down and leave it open until heaps of steam is coming out at start-up.

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    Re: Help! No steam!! For a few minutes, anyway...

    Man your quick java ;D

  5. #5
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    Re: Help! No steam!! For a few minutes, anyway...

    Is there another way guys?
    Like fixing/changing the valve.

    Obviously it wasnt previously a problem.
    Something has changed and needs to be corrected.

  6. #6
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    Re: Help! No steam!! For a few minutes, anyway...

    Thundergod,

    If the vacuum break is operating correctly it will open just before the pressure in the boiler drops to zero (only a fraction of a PSI)..... and at this point the boiler is full of steam.... it then condenses and is replaced by air sucked in via the valve...(as it is designed to do).... so the boiler is full of air at atmospheric pressure - no collapsed boiler.

    You then turn on the heaters, initially the air in the boiler heats up and expands - but not much pressure is generated and the vacuum break stays open - some air escapes.... eventually some steam is produced, the pressure starts to increase more rapidly and the vacuum break closes (again at one PSI or less..... at this point the boiler is still mostly air..... which wont froth milk and the pressure dissipates almost as soon as the steam wand is open.... eventually all the air is flushed out and the boiler operates normally.....

    So you could either leave the wand open during heat up (most cafes do this when they turn the machine on 1 hour before opening) or you could open the wand and bleed off all the air / steam until a steady stream of pure steam is exiting...

    Cant see any other solution (other than an extra valve which stays open for X minutes after switch on to bleed the air).

  7. #7
    Sleep is overrated Thundergod's Avatar
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    Re: Help! No steam!! For a few minutes, anyway...

    Then why was it working to Paolos satisfaction before?

    Any idea whats changed?

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    Re: Help! No steam!! For a few minutes, anyway...

    Quote Originally Posted by Thundergod link=1177460897/0#6 date=1177466586
    Then why was it working to Paolos satisfaction before?

    Any idea whats changed?
    The vacuum break is typically a small disc with an O ring on the top, the disc slides along a shaft inside a cylinder. The disc is raised by the pressure in the boiler until it seals the opening at the top of the cylinder....

    On older units the "sliding" of the disc becomes more difficult (due to residue on the shaft) and so it takes more pressure for it to seal.. the O ring loses some of its sealing ability so leaks until it is sufficiently hot to seal properly - both these were noticed on my machine prior to overhaul... so steam escaped from the valve for some time. No air in the boiler!!!!

    Post overhaul, the disc pops straight up as soon as the slightest pressure is indicated on the gauge and the new O ring seals instantly - resulting in lots of air in the boiler.

  9. #9
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    Re: Help! No steam!! For a few minutes, anyway...

    Thanks, JavaB!

    Any idea where I could look for this "Vacuum break"?

    I would like to beat this "quirk".

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    Re: Help! No steam!! For a few minutes, anyway...

    JavaB...

    Is that what might be called a "pressure relief valve"?

  11. #11
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    Re: Help! No steam!! For a few minutes, anyway...

    Quote Originally Posted by Paolo link=1177460897/0#9 date=1177468916
    JavaB...

    Is that what might be called a "pressure relief valve"?
    Nope, the pressure relief valve opens when the boiler is over pressure.....

    What you are looking for is often at the top of the water level tube, or sometimes on the boiler.... it generally looks like a tube which is open at the top and you can look into it and see the disc which moves up and down....

    I dont know if you can "fix" it.... as judging by the professional machine course I attended.... you need to open the steam valve on all boiler machines to let the air out..... (mine didnt have a problem when the valve leaked - i.e. it was faulty - but once fixed I have the same problem)....

    But I leave mine on 24/7 - so not an issue!

  12. #12
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    Re: Help! No steam!! For a few minutes, anyway...

    On the top of my sightglass my machine has a brass sleeve that contains a stainless steel ball...which acts as a valve.

    This sounds like what you talked about, JavaB.

  13. #13
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    Re: Help! No steam!! For a few minutes, anyway...

    Quote Originally Posted by Paolo link=1177460897/0#11 date=1177470320
    On the top of my sightglass my machine has a brass sleeve that contains a stainless steel ball...which acts as a valve.

    This sounds like what you talked about, JavaB.
    Yep, sounds similar.... just using a ball rather than the disc.... probably a spring underneath which pushes it up to seal.... and when the machine is cooling down the vacuum inside the boiler sucks the ball down and lets the air in....

    If you stop the air getting in, atmospheric pressure on the outside of the boiler will crush it - so be careful what you do! :(

  14. #14
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    Re: Help! No steam!! For a few minutes, anyway...

    Well there you go.....

    And I thought that my Futurmat had a problem!

    It sounds like what is happening is what is meant to occur.

    Thanks for the piece of mind JavaB.

    The professional machine course sounds interesting. Do you have a number that I could contact?
    Maybe one could be arranged on the East side...

  15. #15
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    Re: Help! No steam!! For a few minutes, anyway...

    Paulo,

    I did the course at the Barista Academy over here in WA..... You might find one of the site sponsor can offer something similar over East....

    Its well worth doing if you can get onto one! Commercial machine use is quite a bit different to the domestics.

  16. #16
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    Re: Help! No steam!! For a few minutes, anyway...

    I call it a "false pressure", and it happens when the ANTI VACUUM valve is stuck SHUT. ie it did not open when you turned off the machine and it cooled down, and therefore it did not allow atmospheric pressure to equalise into the boiler.

    When you turn the machine back on it goes into a false pressure situation exacty as you have found, then rights itself after you bleed off a steam valve.

    Anti vacuum valves are supposed to open and shut every time the machine is swiched on and off, to stop false pressure. But they stick shut eventually due to a build up of scale from the passage of steam.

    You get around this in the following way: when you turn off the machine you open a steam tap and let all the steam bleed off...leave the valve open. When the steam is exhausted, atmospheric pressure equalises into the boiler.

    When you switch on again, make sure the steam valve is still open. Leave it open until the machine has built up enough steam for it to start leaking out the steam pipe. When you see it leaking, close the tap. The machine will then very quickly reach operating pressure, and there will be NO false pressure situation.

    If you do the above all the time, it doesnt matter if the anti vacuum valve is stuck shut.


    To stop the anti vacuum valve from sticking shut you can occasionally just tap the top of the valve with something (screw driver handle) while the machine is on, to make sure its not stuck. The steam pressure will just bounce it straight back up and reseat it.

    A stuck valve is not a failed valve...its just struck. Tap it occasionally and you will stop it sticking. If it is stuck, tapping will unstick it and make it reseat itself. *

    Anti Vacuum valves eventually fail in that the passage of steam will create a "track" through the valve, or the valve will wear in some way, or a seal will fail ( depends on the type of valve). *In this case the valve wont reseat itself properly and will leak steam all the time. Only then will I consider replacing the valve.

    Otherwise, you just make the spare parts man very well off indeed from selling anti vacuum valves to people that didnt need to buy them...they just needed to tap them!

    By the way, remember these items are directly concerned with steam delivery so if you are going to tamper with or "tap" these valves, please take care not to burn yourselves.

    Apologies for the lengthy reply (but how else would you describe and explain the above?????).

  17. #17
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    Re: Help! No steam!! For a few minutes, anyway...

    Curmudgeon that dosent sound quite right if your valve was stuck shut dosent that mean you would get a collapsed boiler from the vacum created when you turn the machine off??

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    Re: Help! No steam!! For a few minutes, anyway...

    Sorry Segrave, but JavaB is spreading factoids that arent strictly correct. These are pressure vessels that can withstand both positive and negative pressure. The negative pressure that results from a sealed boiler is less than 1 bar implosive pressure and should be well below what a boiler can withstand.

    What Curmudgeon describes is common on older machines. The anti-vacuum valves can get stuck closed. I suspect it is the rubber in the o-ring seal softening and deforming until it becomes sticky enough to, well, stick.

    This is the case on my Pav and I had it on my Bezzera. A new o-ring can fix it, or you can do what was suggested and what Im currently doing on the Pav, and that is tap the anti-vacuum valve open just before turning the machine on.

    The false pressure effect will cause a brief spurt of steam followed by nothing until the boiler heats up enough to generate a real pressure. This can take some minutes, after which the machine will run normally.

    The air in the boiler phenomenon is completely different and will not result in a drop of pressure other than what is normally observed when opening a steam valve. What it will do is blow large bubbles in your milk (untill all the air is removed).

    Im still puzzled as to what causes this false pressure. But this is whats happening.

    On my machine, the anti-vacuum valve is on top of the sight glass.

    Cheers,

    Mark.

  19. #19
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    Re: Help! No steam!! For a few minutes, anyway...

    Quote Originally Posted by Sparky link=1177460897/15#17 date=1177503445
    Sorry Segrave, but JavaB is spreading factoids that arent strictly correct. These are pressure vessels that can withstand both positive and negative pressure. The negative pressure that results from a sealed boiler is less than 1 bar implosive pressure and should be well below what a boiler can withstand.

    Mark.
    Mark,

    Whilst I agree that it is unlikely the boiler will collapse or implode, vacuum brake valves are stated to prevent this happening.... for example the following quote from Kadant Johnson who design these valves for various boilers:

    Quote
    Kadant Johnson Vacuum Breakers provide a simple, dependable
    way to relieve any unwanted vacuum condition that may
    develop in a closed vessel or pipeline. They can be used to
    prevent contamination from back flowing in fluid handling
    systems and to protect equipment against collapse or implosion.
    Unquote

    To my naive way of thinking a vacuum breaker is there to prevent a vacuum..... so for what other reason would you want to prevent a vacuum??? :-/ :-/

    EDIT:

    Just a thought.... painful as it might be....

    Assuming we allow 1 Bar vacuum to be established in the boiler..... what effect would that have on the pressurestat and the pressure gauge etc.... devices which are designed for positive pressure....can these be forced to travel beyond their design range... maybe the vacuum on the diaphragm of the pressurestat is what causes the false pressure initially.... i.e. it switches on a 1 Bar increase... above the previous -1Bar.

    Even the steam valve seals would be pulled hard into their seats by the vacuum.

  20. #20
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    Re: Help! No steam!! For a few minutes, anyway...

    Dont even think that the vacuum in one of these vessels would approach -1bar. -1bar at sea level equals total vacuum, and having been heavily involved in vacuum moulding processes in my working life I can assure you that the machinery involved in getting to near -1bar is quite impressive.
    Having stated the above I can also assure you that a negative pressure differential of as little as 2 or 3 psi, in the wrong circumstances, can have a devastating effect.

  21. #21
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    Re: Help! No steam!! For a few minutes, anyway...

    Good discussion here chaps.

    Note the small vacuum that occurs when the anti vacuum valve is stuck and the machine is off and the steam valves havent been opened, is the most common cause of rubbish being sucked back into the boiler through the steam pipes.

    And this is why equipment traders such as ourselves always recommend that when a machine is switched off, a steam valve should be opened and left open atleast until all the steam is gone.

    This is also why we advise all purchasers never to soak steam pipes. *The vacuum discussed above sucks back
    a) the garbage you are trying to soften by soaking (that shouldnt have been there in the first place) and
    b) the garbage you are soaking with (detergents, chemicals etc).

    And I can confirm, the vacuum created never causes an implosion in these boilers....and, false pressure is a very common occurence because many still dont know they should be opening the steam pipes when switching off. Nothing to worry about, just manage the equipment properly.


    Regardz,
    FC.

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    Re: Help! No steam!! For a few minutes, anyway...

    Quote Originally Posted by JavaB link=1177460897/15#18 date=1177506360


    To my naive way of thinking a vacuum breaker is there to prevent a vacuum..... so for what other reason would you want to prevent a vacuum??? :-/ :-/
    How about to prevent the false starts that this topic is about. Also to prevent suck back of nasties into the boiler as FC added.

    If there is false pressure in the boiler, the boiler wont heat up to the operating pressure, but will otherwise look operational. As soon as someone tries to froth some milk or make a shot youll get.... Not good for a commercial environment, and also not good for home machiens on timers...

  23. #23
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    Re: Help! No steam!! For a few minutes, anyway...

    Quote Originally Posted by Fresh_Coffee link=1177460897/15#20 date=1177546331

    Note the small vacuum that occurs when the anti vacuum valve is stuck and the machine is off and the steam valves havent been opened, is the most common cause of rubbish being sucked back into the boiler through the steam pipes.

    And this is why equipment traders such as ourselves always recommend that when a machine is switched off, a steam valve should be opened and left open atleast until all the steam is gone.

    Regardz,
    FC.
    Thanks FC.... the penny has dropped!! ::)

    The instructor I had was very insistent (almost overly so) that we ALWAYS open the steam valves to prevent damage to the machine at shutdown..... so Id assumed that the damage was physical damage caused by the vacuum :-[..... but sucking back rubbish into the boiler was obviously the reason!!!

    The false pressure would cause embarrassment (might damage your reputation).... but I couldnt see it damaging the machine.

    He was also very insistent on never soaking the wands by the way....

    Thanks again. :)

  24. #24
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    Re: Help! No steam!! For a few minutes, anyway...

    A negative pressure as little as -1psi (very easily created) will support a column of water just over 650mm high, so as FC has said it will suck quite a bit of junk back into your boiler.

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    Re: Help! No steam!! For a few minutes, anyway...

    I think I have the gist of the above accumulated wisdom...but just to be sure:-

    Referring back to FCs comment....


    "Note the small vacuum that occurs when the anti vacuum valve is stuck and the machine is off and the steam valves havent been opened, is the most common cause of rubbish being sucked back into the boiler through the steam pipes."



    am I right in thinking that if an anti-vacuum valve IS stuck...that the only way that rubbish can actually be sucked into the boiler is if proper protocol has not been performed, leaving rubbish (milk solids) caked in the steam wand by virtue of it not being flushed out straight after being used?
    These solids then get sucked into the boiler when the negative pressure (vacuum) occurs when the steam tap is opened in a tank that has residual air (but not much developed steam) yet...

    Or to put it another way....does this mean that if the opening of steam taps did not occur prior to shutdown and prior to startup...that the boiler cant become contaminated if a healthy shot of steam was released after the steaming of the last milk?

  26. #26
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    Re: Help! No steam!! For a few minutes, anyway...

    Paolo,

    Firstly Ill repeat what I was told to do at the course (and have been doing religiously)..... and the reasons for this was explained by FC above...

    When texturing milk, withdraw the wand as you turn off the steam so that it is just below the surface as the steam is turned off.... if deep in the jug (at 60C) the steam in the wand will condense sucking in some milk.

    Wipe the wand down immediately to remove the milk residue (with a wet wipe kept for just this purpose.... not wiping the bench etc)....

    Give a shot of steam (into the drip tray) to blast out any milk which might have happened to get sucked in.

    When shutting the machine down- open at least one steam wand.... and leave it open until all steam is exhausted...

    When starting up, ensure at least one wand is open until a strong jet of steam is emitted and then close the wand (a fully operational vacuum break might make this unnecessary..... but thats what I was told to do)

    NEVER place a jug with any cleaning material under the wand to "soak off" baked on milk.... (and Ive seen cafes do that).... the steam in the wand will condense and the cleaning material will be sucked up into the wand.... and if there is a vacuum in the boiler..... its only a short route into the boiler and the water will be contaminated with the cleaning agent and the crap inside the wand which you were removing.... (that is the "damage" to the machine which I had interpreted as physical damage to the boiler :-[ :-[)

    So yep, bad technique.... generally from people not correctly cleaning the wand after each milk texturing.... allowing it to get into such a state that drastic action is needed..... and soaking it when the machine is switched off (and cooling down) seems to be the answer...... BUT IT ISNT!!!!!

  27. #27
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    Re: Help! No steam!! For a few minutes, anyway...


    Hi Paolo,

    Your problem really sounds like a stuck anti-vacuum valve as per Curmudgeons suggestion.

    As for the vacuum sucking back junk into the boiler. Well that would be hard to completely mitigate, because even though you may have a cleaning technique that sounds good, there is a vacuum behind the steam and hot water valves that will try to bring any residual into the boiler. Maybe a CSers fastidious routine will be enough to prevent this. But it would be easier to fix the anti-vacuum valve and then the problem is solved and the machine will be operating normally again.

    Cheers,

    Mark.



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