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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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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,452
Location: UK
Expertise: I love coffee

Posted Mon Mar 31, 2014, 1:31pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

CarloM Said:

What's weird about auto-fill is that for the first month of ownership, it almost always kicked on when I turned on the V2B. I use it 1-2 times a day, every day, unless I'm away from home. But in the 5 months since, it only kicks in slightly less than half the time. The only thing I can think of is at about a month or so into ownership I drained the boilers via the bottom taps. I reattached the caps on the tap securely, there is no leak, and I double-checked that. But perhaps not long after that emptying of the boilers back around the second month of ownership, the autofill frequency has changed. I'm not sure why that is. Coincidentally in that first month I never had the cavitation sound. At some point I may fully drain and refill the boilers again to see if it helps.

To be honest, the sound now only happens around a 35-40% of the time, and as long as I haven't forgotten that the machine was on for several hours, it's very short in duration and intensity and doesn't really bother me any more. Draining boilers was such a PITA (based on my kitchen configuration) that I don't really want to go through with the trouble again unless I have to.

Good luck!

Posted March 31, 2014 link

The autofill is purely controlled by the probe in the steam boiler, nothing else. The autofill is more likely to come on when switched on from cold simply because the water in the steam boiler contracts as it cools and may dip below the level of the probe. hence statistically, it's more likely to autofill when the machine is switched back on after a cold start. When these machines autofill, they all have a minimum on time, so that the level goes above that of the probe, which prevent them then re-autofilling, the second any steam is drawn, which they would do if the fill stopped the second the water reached the probe tip. Your Gicar boxes are different models being 110V, so it's possible some of the autofill parameters are slightly different. Gicar have also changed them from time to time and has variance on models of box. I have had 2 RL30s made in different years with different fill characteristics. I don't have any idea why yours is now different. perhaps your Kitchen is now warmer, perhaps the usage pattern has changed...just don't know, but it doesn't sound like you have a problem. certainly draining the steam boiler shouldn't make any difference.

Draining the brew boiler will, however, introduce air, which will take a few days to get reabsorbed....this air cushion is "bouncy" and unlike an absolutely full brew boiler, will create a cushion against the pump. A full brew boiler drops to near Zero pressure the second the lever is lifted, then back to 9 bar, but with air inside, this isn't so and creates a momentary resistance that lasts much longer (and needs filling). it's a potential issue on all dual boiler machines fed from a tank using a standard Rotary Vane pump. I have suggested things that can mitigate this to QM, but as yet have not had pictures of the interior of a UK machine to see if it's been done. As you can imagine, because we're not getting the problem over here, it's not high on the priority list of the UK retailer, although they did vist QM last week in Italy and raised the issue again (at my request). your right to not let it bother you, because it's not going to do any harm to your pump over it's service life. The one routine I always do, it became a habit with ever prosumer machine, I always switch on and then lift the lever to draw water through the group. I do this out of habit, because most DB machines have no sensor in the brew boiler, if something has happened and it's below the heating element for whatever reason, this routine is both protective and diagnostic. If it takes ages for water to come through the group...something is wrong and I can switch off to investigate. It also has the benefit of removing any head-space that has formed in the brew boiler (for numerous reasons), This routine, may help you?

As for boiler draining, it sound like the US machines don't have these (I hope you do)....which is standard fitment on the UK machines (at my request). You undo the bottom plate (2 screws I think), then stand the machine on a book or something under each foot and slide a tray underneath, reach under and undo the taps. The best way is a tray ready, reach under undo 1 tap, and then slide the tray under outlet, when drained empty tray and repeat for second tap. I insisted on them, because the taps are a PITA to reach when their on the bottom of the boiler and you either have to use a tube, or let it flood out and onto the bottom plate of the machine. QM did send me a video of the correct procedure, which involved case removal (and I think one or two other bits) and trying to shove a tube on the fitting, all done in a workshop. This didn't do it for me.

The picture shows the drain tubes on extension pipes from each boiler leading to the base of the machine, they are literally a few mm inside the plate cover.

DavecUK: draintaps.JPG
(Click for larger image)
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CarloM
Senior Member


Joined: 1 Apr 2013
Posts: 332
Location: Los Angeles
Expertise: I live coffee

Espresso: Vetrano V2B
Grinder: Mazzer Mini-E Type A, SJ...
Drip: Toddy
Posted Mon Mar 31, 2014, 3:16pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

Hi Dave,

I think the drain taps are identical, except in my unit they both don't point nicely out of that hole. One points down towards the metal bottom plate which made draining it messy. I compounded the problem by not doing a full removal of the back and sides. I thought if the taps pointed straight down through the hole it wouldn't be necessary. My mistake. If I ever do need to drain them again, I will make sure to remove the case. Maybe there's even a way to rotate the boiler/tap so that both taps point straight through that big hole so they drain without splashing all over the bottom of the machine?

On occasion I too have lifted the lever when I didn't hear the autofill kick in, and it does reduce (though it doesn't fully eliminate) the chance of the cavitation noise. The good news is, at no point from a cold start have I lifted the brew lever and had a lengthy delay until water comes out. It generally comes out almost instantaneously. Phew!
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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,452
Location: UK
Expertise: I love coffee

Posted Mon Mar 31, 2014, 4:51pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

Remember as well the bounciness I talk about, my theory is it's not a push against the pump, so much as some, but not enough resistance, causing the need for the pump to deliver more fluid than momentarily available, from a high to sudden lower (but not as low as a steam boiler) pressure situation, which is not generally the case when the steam boiler autofills and you would probably never hear the cavitation. This could be compounded by the fact that the balanced bypass may momentarily be operating, which under pressure, may induce vaporisation  (across the bypass system)..in the pump chamber.

It's an odd situation when you have air in the brew boiler in terms of the dynamics of what's happening, I'm not sure I fully understand it, but it would seem that increasing the potential flow to the pump, might help, as will strategies to eliminate head space in the brew boiler at all times. I also suspect that there is a critical point at which this can occur and which it doesn't. it could be related to pump speed (perhaps there is a slight difference in pump speed between UK/US voltage. I always thought there was, because there are pumps suitable for 50 and 60Hz operation with the 60hz being a higher motor speed. This could contribute to the problem....then lastly the higher temperature.

All these factors could be just enough to put the system in the realm where that slight cavitation can occur. Changing any factor, should improve things e.g. reduce the offset (I feel mine is more correct than the 15C of the US machines). Increase the feed pipes, prevent headspace. I'm not explaining the whole thing very well, as it's difficult to do, but I am looking more at the differences that exist..
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 693
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Mon Mar 31, 2014, 5:20pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DavecUK Said:

humour me a little and set it up my way, with a brew offset of 11C or 11.5C and 94C brew temp which I find good for shots. With your current offset the boiler pressure is running at 0.4 bar, not 1.4, because you forgot to deduct 1 bar for atmospheric pressure.

There is a 1 way valve as well which can let by...but for now, just lower that offset a tad to 11C....or whatever that is in old money.

Posted March 30, 2014 link

Consider yourself humored... I am sitting here drinking my coffee.... I used the F equivalents to your C temps because that is what I am used to.  I can't decide if it is better, worse or the same as the shots I normally make. I will tell you that the crema seemed darker.  The shot is definitely not bad at this temperatures so I will leave it there a few days before I make a decision.... and see if it helps with the cavitation issue as well.
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sharky
Senior Member
sharky
Joined: 9 Jan 2013
Posts: 186
Location: Calgary, AB
Expertise: I love coffee

Espresso: QM Vetrano 2B
Grinder: Compak K3 Touch
Posted Tue Apr 1, 2014, 1:48pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DeanOK . . . I feel for ya, man!  It sucks to have spent over $2,200 on the V2B and you're still battling the dreaded 'growling' noise with your machine!  I would be pretty upset, too!  I have drained my machine (via drain plugs in boilers) twice now (for travel reasons) & accidently ran it dry once.  My bad . . . !!   I have gotten the 'growler' sounds after I refilled the machine from complete drains both times!  As it filled the boilers, it made the sound, but it only lasted for a second and then it was gone.  I have it on a timer everyday for a 5am start-up for 1-2 lattes and another latte in the afternoon.  It has not made a peep for over a month, since the last time it growled.  Why your V2B continues to 'growl' on a regular basis is a mystery?  I would try it on a timer for your morning coffee and the afternoon . . . rather than leaving it on 24-7.  Try this for a week and see what happens?   Leaving yours on 24-7 appears to be the issue!  Good luck!
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 693
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Tue Apr 1, 2014, 5:06pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

sharky Said:

DeanOK . . . I feel for ya, man!  It sucks to have spent over $2,200 on the V2B and you're still battling the dreaded 'growling' noise with your machine!  I would be pretty upset, too!  I have drained my machine (via drain plugs in boilers) twice now (for travel reasons) & accidently ran it dry once.  My bad . . . !!   I have gotten the 'growler' sounds after I refilled the machine from complete drains both times!  As it filled the boilers, it made the sound, but it only lasted for a second and then it was gone.  I have it on a timer everyday for a 5am start-up for 1-2 lattes and another latte in the afternoon.  It has not made a peep for over a month, since the last time it growled.  Why your V2B continues to 'growl' on a regular basis is a mystery?  I would try it on a timer for your morning coffee and the afternoon . . . rather than leaving it on 24-7.  Try this for a week and see what happens?   Leaving yours on 24-7 appears to be the issue!  Good luck!

Posted April 1, 2014 link

If I turned the machine on for short periods of time like, like most people do, I don't think I would have any issues. If I use the machine several times throughout the day, it does fine. The only time I have issues is when it sits for 12-16 hours or more.... if I let it set for 24-36 hours it will cavitate so badly that it wont pump at all into the team boiler.  My schedule is hectic sometimes and I may be in a hurry in the morning and not have time to make coffee and then I get home so late, I don't drink coffee because of the caffeine so, while not all of the time, it does sit long periods sometimes. I try to remember to open the brew valve and let a few ounces of water through a couple times a day if I am not making coffee, but sometimes I let it slip my mind. I had two lattes today. One this morning and one this evening after my dinner. If I did that every day, the problem wouldn't be nearly has bad, but I probably would hear just a little growl when it first comes on.
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DavecUK
Senior Member


Joined: 21 Sep 2005
Posts: 1,452
Location: UK
Expertise: I love coffee

Posted Wed Apr 2, 2014, 5:12am
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DeanOK Said:

If I turned the machine on for short periods of time like, like most people do, I don't think I would have any issues. If I use the machine several times throughout the day, it does fine. The only time I have issues is when it sits for 12-16 hours or more.... if I let it set for 24-36 hours it will cavitate so badly that it wont pump at all into the team boiler.  My schedule is hectic sometimes and I may be in a hurry in the morning and not have time to make coffee and then I get home so late, I don't drink coffee because of the caffeine so, while not all of the time, it does sit long periods sometimes. I try to remember to open the brew valve and let a few ounces of water through a couple times a day if I am not making coffee, but sometimes I let it slip my mind. I had two lattes today. One this morning and one this evening after my dinner. If I did that every day, the problem wouldn't be nearly has bad, but I probably would hear just a little growl when it first comes on.

Posted April 1, 2014 link

Leaving any prosumer machine on and not drawing water through it for 24 to 36 hours is not really good....Unless the seals are all perfect. This applies to DB or HX machines. With Vibe pumps, you won't really notice anything much.

in fact if I had your schedule, I would probably be looking for this type of solution.

http://www.belkin.com/uk/p/P-F7C027/

It would allow you to simply switch the machine off or on whenever you want and from wherever you are, or put it on a schedule.
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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 Wed Apr 2, 2014, 2:47pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DavecUK Said:

...in fact if I had your schedule, I would probably be looking for this type of solution.

http://www.belkin.com/uk/p/P-F7C027/

It would allow you to simply switch the machine off or on whenever you want and from wherever you are, or put it on a schedule.

Posted April 2, 2014 link

I have been using the new Insight version of this and I love it.

http://www.belkin.com/us/F7C029-Belkin/p/P-F7C029/

It doesn't have a motion sensor built in but it has a built in Kill-A-Watt type usage meter that you can remotely view anytime.  In the event that I'm out at dinner and decide I want a coffee when I get home, I can simply turn it on from my phone at the restaurant and the machine will be fully warmed up for me when I get there.
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DeanOK
Senior Member
DeanOK
Joined: 24 Sep 2012
Posts: 693
Location: OK
Expertise: I like coffee

Espresso: QM Vetrano 2B
Grinder: Vario W
Posted Wed Apr 2, 2014, 4:17pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DavecUK Said:

Leaving any prosumer machine on and not drawing water through it for 24 to 36 hours is not really good....Unless the seals are all perfect. This applies to DB or HX machines. With Vibe pumps, you won't really notice anything much.

in fact if I had your schedule, I would probably be looking for this type of solution.

http://www.belkin.com/uk/p/P-F7C027/

It would allow you to simply switch the machine off or on whenever you want and from wherever you are, or put it on a schedule.

Posted April 2, 2014 link

Do you think hooking it to municipal water would solve the issue? I can easily get water to the machine, but I haven't because I didn't want to make a hole in the cabinetry for the water line and I didn't want to use municipal water .... it has a lot more minerals than the bottled water I am using now. It would not be hard for me to hook it to municipal water though. I guess putting a softner in is an option, but here again a lot of work. I would rather wait until I do a major remodel of the kitchen and build a dedicated spot for the Vetrano with water and a drain. I kind of have a vision of a small coffee bar with enough room for my grinder and accessories. Not going to happen soon though.

The 24-36 hour example is rare.... 12-18 hours is not unusual. I try to remember to open the brew valve every morning and every evening even if I am not going to make coffee... but I do forget to do it sometimes.
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CarloM
Senior Member


Joined: 1 Apr 2013
Posts: 332
Location: Los Angeles
Expertise: I live coffee

Espresso: Vetrano V2B
Grinder: Mazzer Mini-E Type A, SJ...
Drip: Toddy
Posted Wed Apr 2, 2014, 4:43pm
Subject: Re: Air Bubbles in pickup tube on V2B.. is this a wild theory?
 

DavecUK and CurtG, thank you so much for that iOS power switch solution!!! I've never bought a timer because the time I wake up and the time I get home from work varies greatly and I don't want to have the machine sitting for prolonged periods in case my schedule changes and I'm late an additional hour or two. I'd much rather be able to use my iPhone to turn on the V2B when I'm leaving work, knowing it will have just reached optimum temp when I walk in the door. Also when I wake up, I use my phone as an alarm, so I can quickly cycle over to the app and turn on the machine knowing that when I step out of the shower it's good to go. Gonna hit up Google and hopefully find the best price for that Belkin piece of magic! :D
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