# Do these burrs look okay please?



## Ghostrider (Jul 3, 2008)

This is not some sort of bizarre trick question, so please just say what you see. Please would people comment on the condition of these burrs as they appear in the photos? I am not the best at assessing burr condition. For reference, they are in a Macap MXA. Thanks one and all.


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## DavecUK (Aug 6, 2013)

A little more information might be helpful?


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## Ghostrider (Jul 3, 2008)

Hi Dave,

We have a very old rotary HX that most likely has an HX pressure leak. One of the resulting symptoms has been extremely sour espresso like lemon juice, there have been other issues with a spurious noise and we think the OPV was letting in as described in your article. She is being retired but I just had one of those stupid panic moments and thought might it be the grinder burrs re the souring.


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## DavecUK (Aug 6, 2013)

Ghostrider said:


> Hi Dave,
> 
> We have a very old rotary HX that most likely has an HX pressure leak. One of the resulting symptoms has been extremely sour espresso like lemon juice, there have been other issues with a spurious noise and we think the OPV was letting in as described in your article. She is being retired but I just had one of those stupid panic moments and thought might it be the grinder burrs re the souring.


Ah.....I actually meant any more information about the grinder, although I don't believe (well actually I'm 100 certain), the grinder burrs won't be the cause of sour espresso....


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## Ghostrider (Jul 3, 2008)

Thanks Dave, much appreciated. I thought it looked fine but the whole machine fault thing has turned into a rather surreal and long drawn out mind bender, so I decided to just ask for confirmation. I am grateful. Nothing unusual about the grinder. Sorry, I should have realised the question, it's behaving as would be expected. It was just me over thinking.


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## DavecUK (Aug 6, 2013)

This is what might be happening. The machines anti backflow (one way valve) valve is letting by (assuming the machine is run from a tank, not the mains)...this may well cause enough water to push out of the HX so the thermosyphon stops and the group cools a bit. You pull a shot, this refills the HX and the group warms up again....so a shots pulled a few minutes or som later might be fine....but shots pulled after the machine has been standing a while could be sour.

http://coffeetime.wikidot.com/izzo-alex-anti-backflow-also-called-non-return-valve

It's unlikely you have an HX leak, if you did there would be other symptoms e.g. rising steam pressure when pulling a shot, overfilling steam boilet etc..


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## Ghostrider (Jul 3, 2008)

Oh Dave, thank you. I was seriously thinking my sanity was going. You describe the symptoms perfectly. We did check the one-way valve between the pump outlet and the fluid-o-tech OPV bypass valve (we tried a CMA and Izzo too) and the one-way appeared fine. Perhaps it was not, I certainly wish we had replaced it. Each time we replaced the OPV we could get a closed HX to go over pressure once then it would not do so until the next size up OPV was installed. Eventually it was removed altogether for testing and it still wouldn't go over pressure. The pump had been sucking air occasionally as you describe. This has been going on for months and it so needs to end.

Edit: Just thinking about it, the original one-way valve was removed temporarily when the CMA OPV was installed as it had an integral non-return, but the issue persisted. However, the way it has been, I wouldn't rule out that too letting by. It's been a nightmare.


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