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Air Bubbles in pickup tube on V2B.. is this a wild theory?
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Discussions > Espresso > Machines > Air Bubbles in...  
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DeanOK
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DeanOK
Joined: 24 Sep 2012
Posts: 720
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Sat Mar 8, 2014, 6:54pm
Subject: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

OK... I don't really have a clue about what I am about to talk about, but I want to air it anyway.

I have been monitoring my situation and I routinely get air bubbles in the pickup tube that goes into the tank. They start out as very small bubbles and they continually get larger and larger until there is large sections of the pickup tube that appear to be full of air.

Here is my wild theory:

I leave my espresso machine on 24/7. The water in the tank is around 105F because of the lost heat from the boilers. I think it is fair to assume that there may be other sections of the internal piping that are at even higher temperatures....

... so, I am come up with this theory that oxygen is coming out of solution and creating bubbles in the line... much the way oxygen bubbles form on the side of pan before it starts boiling.

Is this possible or am I out in left field? What little research I have been able to do leaves me to believe this is a viable theory. I need someone with some expertise about this sort of thing to chime in.
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CoffeeRon
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Joined: 26 Apr 2009
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Location: Eatonville, Wa
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Espresso: Wega Lyra, Europiccola(still...
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Posted Sat Mar 8, 2014, 7:31pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

Actually, I believe that's what was being referred to in the last couple posts of your other thread :)
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Tonyv138
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Joined: 16 Jun 2013
Posts: 74
Location: tx
Expertise: I love coffee

Espresso: V2B
Grinder: Mazzer SJ
Posted Sat Mar 8, 2014, 7:59pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

comparing routines:  i keep my V2B only a couple of hours a day, and my GRRRR noise has virtually gone. Also, shortly after the machine warms up, i dump some water through the head, once a day.
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Metatron
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Joined: 10 Nov 2011
Posts: 73
Location: Calgary, Canada
Expertise: I like coffee

Espresso: BDB900
Grinder: Vario
Posted Sun Mar 9, 2014, 9:49am
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DeanOK Said:

OK... I don't really have a clue about what I am about to talk about, but I want to air it anyway.

I have been monitoring my situation and I routinely get air bubbles in the pickup tube that goes into the tank. They start out as very small bubbles and they continually get larger and larger until there is large sections of the pickup tube that appear to be full of air.

Here is my wild theory:

I leave my espresso machine on 24/7. The water in the tank is around 105F because of the lost heat from the boilers. I think it is fair to assume that there may be other sections of the internal piping that are at even higher temperatures....

... so, I am come up with this theory that oxygen is coming out of solution and creating bubbles in the line... much the way oxygen bubbles form on the side of pan before it starts boiling.

Is this possible or am I out in left field? What little research I have been able to do leaves me to believe this is a viable theory. I need someone with some expertise about this sort of thing to chime in.

Posted March 8, 2014 link

As I said in my post in your other thread, just boil your water and let it cool to remove the air. Run a few tanks through and if the noise stops you know the solution.

Leaving the machine on 24/7 is the perfect way to cause the air to come out of solution in your intake. Tonyv turns his on only when he uses it and has fewer problems with cavitation.
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 720
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Sun Mar 9, 2014, 12:20pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

Metatron Said:

As I said in my post in your other thread, just boil your water and let it cool to remove the air. Run a few tanks through and if the noise stops you know the solution.

Leaving the machine on 24/7 is the perfect way to cause the air to come out of solution in your intake. Tonyv turns his on only when he uses it and has fewer problems with cavitation.

Posted March 9, 2014 link

Sorry Jim... didn't catch your comment earlier... If this is the issue, I am not sure if the air comes from the pump or the reservoir. I suspect it's coming from the pump simply because there is a larger amount of water in the pump than there is in the tube that is sticking down in the tank (unless some kind of thermal syphoning is going on). If the heat of the water in the reservoir is the issue, I think a layer of insulation between the boiler and the reservoir may lower the temperature of the water in the reservoir.
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SpaceTime
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Joined: 9 Dec 2013
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Expertise: I love coffee

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Posted Sun Mar 9, 2014, 4:41pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

The 64 thousand dollar question is why after all these months are owners still left to propose "wild theories"???

Is this so mysterious that even those that make the machine still don't have an answer??  That is the part that stumps me.  Anyone? Beuller?
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CurtG
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Joined: 25 Oct 2011
Posts: 27
Location: San Diego
Expertise: I like coffee

Espresso: Quick Mill V2B
Grinder: Baratza Vario
Vac Pot: Hario Nouveau Syphon
Posted Tue Mar 11, 2014, 4:21pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

Did you try sucking on the pickup tube to see if you have a pinhole somewhere on the vacuum side of the pump?
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DavecUK
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Joined: 21 Sep 2005
Posts: 1,466
Location: UK
Expertise: I love coffee

Posted Thu Mar 13, 2014, 10:09am
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

It's very odd, I put it down to the fact that perhaps your machines in the US were shipped with empty tanks and it can take a while for the air to come out. The UK machines don't make that noise, I never see any reports of it. Mine doesn't make that noise....although I did purposely induce a condition to create the noise. By sucking as well as forcing a huge amount of air into the brew side of the machine.. It made the noise much like the US ones were doing. I bled out the air, the noise reduced greatly, then it too a week or 2 to stop completely.

I have suggested some changes to Quick Mill for later models....although I really don't know why they are making a noise for sure. Usually this sort of problem is one of priming against a hot tank, or a leaky one way valve in the brew circuit (limescale, or perhaps faulty, swarf etc..). The brew boiler eventually fills completely (for various reasons I won't go into), but up until then there is a back pressure created within the brew boiler that is effectively "springy" rather than static , because of any air space. A static pressure will immediately move to 0 when you lift the brew lever, air space wont.. Is it any of these I really don't know.

I have tried all sorts of routines at home and mine really doesn't make the noise. I have once or twice had a slight noise if the machine has been on for 15 hours without pulling a shot, but again only occasionally. Also if mine does very rarely make any noise, it is literally for a few 10ths of a second, really really brief.

There are only 2 possible differences in the machines.

  1. I don't run my brew boiler with as high an offset as the UK machines (mine is 11C I think). I personally think the US machines have an offset that's too high, so for any given brew temperature you set, your boilers are much hotter. My advice would be to run with an offset of 11 or 11.5C, because that is the correct offset in my opinion and you never know it might also help with the noise..

  2. Perhaps it's something to do with startup torque and the time it takes for the motors in the US to get up to speed??

Regardless of the fact that its a little bit guesswork,  I suggested that QM should do a number of things which might help.

  1. Increase the size of the pump inlet tubing and also review the 1 way valve if the diameter is below a certain size i specified (can't remember what that was ATM, but I "think" it was 6 or 8mm).

  2. Relocate the take off to the  Expansion Valve used to relieve Hydraulic pressure in the brew boiler, due to cold water expanding when it heats (basically placing it on a T-Piece together with the take off for the brew pressure gauge (so it's all at the top of the boiler).  I should stress that this will only help to remove any headspace within the brew boiler faster (e.g. a few days instead of a few weeks). BUT, if there is any pull back thru this valve, that will bleed back out again every time it heats up.

It is my understanding that new machines from the factory now incorporate these changes. The retailer i did the UK reviews for did confirm that they had been told by QM that they were doing it all....but until some more ship to the UK, I can't ask the retailer to have a check and see if it was done...and then of course that "might" only be for UK machines. However, i did advise to make this change worldwide.

The big problem is, it's not a problem over here?
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CurtG
Senior Member


Joined: 25 Oct 2011
Posts: 27
Location: San Diego
Expertise: I like coffee

Espresso: Quick Mill V2B
Grinder: Baratza Vario
Vac Pot: Hario Nouveau Syphon
Posted Fri Mar 14, 2014, 4:21pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

Thanks for all your efforts to help us V2B owners Dave.  I'm in your boat as well; my machine doesn't make the noise so it's hard to help someone else troubleshoot.  It doesn't seem to be a UK vs US issue, more of a machine to machine issue.

I can say that I adjusted my offset very soon after getting my machine.  Did that solve the issue?  Not sure, but I like the result in the cup as I have it set.  I also never get bubbles in my pickup line.  It would be an interesting test to simply lower the set temp by 10 or so degrees F after finishing with the machine one day and see if the bubbles still come back the next morning.
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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,466
Location: UK
Expertise: I love coffee

Posted Sat Mar 15, 2014, 3:10pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

CurtG Said:

Thanks for all your efforts to help us V2B owners Dave.  I'm in your boat as well; my machine doesn't make the noise so it's hard to help someone else troubleshoot.  It doesn't seem to be a UK vs US issue, more of a machine to machine issue.

I can say that I adjusted my offset very soon after getting my machine.  Did that solve the issue?  Not sure, but I like the result in the cup as I have it set.  I also never get bubbles in my pickup line.  It would be an interesting test to simply lower the set temp by 10 or so degrees F after finishing with the machine one day and see if the bubbles still come back the next morning.

Posted March 14, 2014 link

The other thing of course is good water...98% of espresso machine problems are cause by bad water. It only needs the one way valve not to seat perfectly and you would get that problem.

I do do what I can to help, the trouble is I only have the power of my reviews behind me and whether they respect my opinion or not. I don't buy large quantities of machines, so I have no financial muscle.
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