# thermosyphon stall?



## ArisP (Dec 17, 2019)

G'day folks,

My machine refused to pass 81C today, even after leaving it on for 1h. That's weird, never did that before. Made a coffee to try and force it to heat up, but neither the coffee itself nor the water from the hot water tap were hot (enough). All the while, the pressure reading in the boiler was rock steady at 0.9 bar (I set it there), even through making the coffee.

So I thought that there might be air trapped in the loop, and opened the tap of the steam wand. The pressure dropped immediately to about 0.3 bar, and now after letting the machine on for about 10 mins, the temperature is back up to 96C and climbing.

So, was that a thermosyphon stall, or an indication that something more sinister is happening?


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## catpuccino (Jan 5, 2019)

Sounds like a stall, check this resource: http://www.espressomyespresso.com/stall.html

Can be a one off, can also be a symptom of other problems. Open it up (what machine?) and have a quick visual check for leaks.


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## DavecUK (Aug 6, 2013)

*To save a bit of time and speculation it would be useful to know what machine you are talking about and how old it is e.g. date of original purchase?*

In the absence of any information I'm going to guess it's an HX machine and from your description of events, that the vacuum breaker stuck closed. Usually a sign of a "sticky seat" caused by poor quality water, note; I didn't say hard water because it's not just hardness that causes problems.

It might not stick again for a while, but as time goes on it will stick more frequently. Remove it, disassemble it, clean it, possibly replace the viton or FKM o ring (if it's that type), or if necessary replace it if it keeps happening. Often a temporary fix can be obtained by pressing it down when under good steam pressure and blowing off steam thru it, can sort of steam blan the seat sometimes.

I don't believe it is a thermosyphon stall....although a stall can have similar symptoms there is one symptom you mentioned that doesn't fit with TS, but does with sticky vacuum breaker..


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## ArisP (Dec 17, 2019)

Sorry gents, it is in the topic "tag" that the machine is an E61 HX, but to be precise, it is a La Scala Butterfly made in 2004. No need for bold text...

I do also believe that it could be a sticky vacuum breaker, I'll look into it a bit more once it cools down.


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## DavecUK (Aug 6, 2013)

ArisP said:


> Sorry gents, it is in the topic "tag" that the machine is an E61 HX, but to be precise, it is a La Scala Butterfly made in 2004. No need for bold text...
> 
> I do also believe that it could be a sticky vacuum breaker, I'll look into it a bit more once it cools down.


 I emphasised what I thought would be very useful information because sometimes people still don't give it even when it's asked for, they either don't see it, or do not have enough experience to understand the importance of it.. I rarely know peoples level of experience, I don't search or view by thread tags. The tag gave the minimal information and for others benefit reading this, not all E61 HX machines have the same Vacuum breaker systems, or thermostatic controls e.g. a pressurestat. This means they may not suffer from false pressure and it could have been something else, hence make and year of machine is very important to know.

It's a little disappointing you felt bold text was more important pull me up on, than saying, "thanks for the help"?

Good luck with it.


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## ArisP (Dec 17, 2019)

DavecUK said:


> I emphasised what I thought would be very useful information because sometimes people still don't give it even when it's asked for, they either don't see it, or do not have enough experience to understand the importance of it.. I rarely know peoples level of experience, I don't search or view by thread tags. The tag gave the minimal information and for others benefit reading this, not all E61 HX machines have the same Vacuum breaker systems, or thermostatic controls e.g. a pressurestat. This means they may not suffer from false pressure and it could have been something else, hence make and year of machine is very important to know.
> 
> It's a little disappointing you felt bold text was more important pull me up on, than saying, "thanks for the help"?
> 
> Good luck with it.


 No worries Dave, I asked for an opinion only, if you feel you have been "told off", then that's on you mate...

Anywho, insecurities aside, I did take the vacuum breaker off, read below if interested, cheers anyway.


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## coffeechap (Apr 5, 2012)

Not everyone has to have the same view point, unfortunately bold text or capital letters is often taken as shouting a point on the internet!


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## ArisP (Dec 17, 2019)

Now, for anyone else that might be in the same or similar predicament, I waited for the machine to cool down a little, until it was just warm to the touch.

Then, using 2 wrenches to counteract the torque, I removed the vacuum breaker. To be honest, it didn't look too bad, the pictures below are probably a bit scary, but the breaker moved with ease in my hand. That aside, I removed the leftover teflon tape, gave everything a good cleaning, and back she went.

Happy to provide more details if anyone needs help.


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## NewboyUK (Jul 14, 2018)

Not thermosyphon stall but airlock in the boiler is my 2p.

When turning it on to heat - have the wand open till it steams then shut it. Like a backup for the antivac.


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## John Yossarian (Feb 2, 2016)

Did you use some food grade grease on the Viton o-ring? I have noticed that, even though I live in a soft water area, that helps with longevity between cleaning.


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## NewboyUK (Jul 14, 2018)

John Yossarian said:


> Did you use some food grade grease on the Viton o-ring? I have noticed that, even though I live in a soft water area, that helps with longevity between cleaning.


 Surely if you grease the ring it would stick more and not drop when the pressure drops?


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## ArisP (Dec 17, 2019)

Yeah, I wanted to grease the piston/plunger ring assembly, but I didn't as I also felt it could "gum up" and not let it drop back down again.

Anyway, the search continues, it wasn't the vacuum breaker that allows air into the system.


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## NewboyUK (Jul 14, 2018)

I think it more the anti vac not allowing air OUT of the system

Im pretty sure if it sticks closed while heating up - what you explained would happen.

See what i said above about leaving wand open while heating every time and it proves my point


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## ArisP (Dec 17, 2019)

NewboyUK said:


> I think it more the anti vac not allowing air OUT of the system
> 
> Im pretty sure if it sticks closed while heating up - what you explained would happen.
> 
> See what i said above about leaving wand open while heating every time and it proves my point


 Sorry ,just to clarify, the vacuum breaker will shut closed once the pressure in the boiler increases sufficiently; beyond that point, any air that might be trapped or created in the system cannot escape via the vaccum breaker.

On your point, yes leaving the wand open or opening a few times along the heat up does get rid of the air, but the question remains where/ how is it created and, more importantly, why now?

I appreciate the suggestions, but not trying to put a bandaid on it, I want to get to the root of the problem.


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## NewboyUK (Jul 14, 2018)

Because the vac may have been temporarily stuck shut and you may or may not have pulled off water and you may have caused an air lock in the boiler which causes the pressure sw to report its up to pressure but wont be up to temperature because of the air lock... Blah blah

Out of the 4000 machines i have fixed over the time as a service engineer - thats what i would look at


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## ArisP (Dec 17, 2019)

NewboyUK said:


> Because the vac may have been temporarily stuck shut and you may or may not have pulled off water and you may have caused an air lock in the boiler which causes the pressure sw to report its up to pressure but wont be up to temperature because of the air lock... Blah blah
> 
> Out of the 4000 machines i have fixed over the time as a service engineer - thats what i would look at


 Cool, thanks.

I did a bit more digging, and found that, even though I cleaned it, the vacuum breaker was stuck in the closed position (up) after the boiler had cooled down.

Took it off, again, and took it apart and cleaned it, again. I now have put it back on and it seems to be working properly, but not sure how something so simple can be failing. I mean, once the pressure in the boiler has been removed, all it needs to open again is gravity. No scratches in the shaft, the rubber ring has not worn out...

Anywho, I think I should order a new one... any recommendations?


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## coffeechap (Apr 5, 2012)

This really is a consumable part and as much as folk like to reuse stuff, it is much wiser just to buy a new one, then you won't have these issues.


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## John Yossarian (Feb 2, 2016)

NewboyUK said:


> Surely if you grease the ring it would stick more and not drop when the pressure drops?


 It has not caused any issues with mine yet. After all it is a thin film (that would not polymerase to form a sticky, gunky thing) that prevents the direct contact between the limescale and the o-ring. The under-pressure that is being created upon cooling surely would pull back the vacuum breaker in its initial position.

Anyway, the OP has resolved the issue and all is good.


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## Deidre (Aug 13, 2019)

NewboyUK said:


> Because the vac may have been temporarily stuck shut and you may or may not have pulled off water and you may have caused an air lock in the boiler which causes the pressure sw to report its up to pressure but wont be up to temperature because of the air lock... Blah blah
> 
> Out of the 4000 machines i have fixed over the time as a service engineer - thats what i would look at


 Can an airlock in the boiler also cause the pump to be unable to top up the boiler?

Occasionally (and only after a number of shots have been pulled over the course of a day), instead of the pump automatically kicking in & topping up the boiler, it fails to engage; when this happens I turn the machine off, let it sit for 1 or 2 hours, and then turn it back on, and all is well again... it starts up & fills the boiler no problem. Is this also the behaviour of an airlock?


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## ArisP (Dec 17, 2019)

Sounds like the water fill level probe might be malfunctioning.


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## Deidre (Aug 13, 2019)

ArisP said:


> Sounds like the water fill level probe might be malfunctioning.


 Thanks, but no, it doesn't seem to be the probe (checked this early on). But some hindrance is occasionally blocking the normal flow from tank to pump to boiler. I suspect air in the water line or boiler is involved (and perhaps because I experiment with some unusual preinfusion approaches with the lever in various positions?), but I really don't know for certain. It only happens on days when I pull more than 3 or 4 shots over the course of a day, and during the day, the tank, pump & boiler navigate each other perfectly. When it does happen, I simply turn off the machine for an hour or so & that solves the hiccup or whatever it is. The machine consistently behaves beautifully, after it has had a short rest in the "off" position, with no intervention. Strange. ?‍♀?


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## NewboyUK (Jul 14, 2018)

You may get more response if you create your own thread and tell us what machine you got?


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