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Thread: La Cimbali Junior S Sirai Pressurestat needs descaling

  1. #1
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    La Cimbali Junior S Pressurestat needs descaling

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi

    I have a La Cimbali Junior S (internal water tank) which I bought new about 8 years ago. I'm careful to use filtered water when filling the machine.

    Normally the deadband on my machine is approximately between 0.9 - 1.1 bar.

    On the week-end the boiler temperature kept rising and didn't stop until it got near 1.5 bar and when I steamed milk it dropped to around 0.6 bar. Next time I turned the machine on it didn't stop at 1.5 bar and nearly entered the red zone on my guage so I manually turned the power off and released steam pressure to drop the high pressure in the boiler. I have tried lubricating the spring on the side of the pressurestat and freeing it up but it hasn't made any difference.

    From my research it would appear that I need to descale the pressurestat diaphragm as it's stuck in the open position. The pressurestat has a brass body and has a large spring on the side. A picture of the pressurestat is attached.

    Can people please advise whether descaling the pressurestat is something that I can do myself?

    If it is, could someone please provide step by step instructions on how to take it out and descale it?

    Thanks

    Graham
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    Last edited by GCM58; 24th January 2017 at 10:34 AM.

  2. #2
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    Hi Graham, I did one a few years ago, it wasn't too hard. Just unbolt it and pull it apart and clean the the scale off the parts then put it back together.

    Sorry, that's all the details I remember now. Have a go.

  3. #3
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    Thanks TRRR.
    I took the initiative and unbolted it and there is scale inside the pressurestat and pipe so will take it apart and descale it.
    I believe that I may also have to take the pipe of the boiler as well to clean out the scale from that pipe as well. If I take the pipe off the boiler do I need to use some thread tape on it to reseal it when I put it back on?
    Cheers Graham

  4. #4
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    I think most brass pipes and fittings seal at the end into some socket and so there is no point in using thread tape

  5. #5
    Mal Dimal's Avatar
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    Definitely don't use any thread tape or similar....
    Small pieces may end up in the hydraulic circuit causing blockages in small orifices.

    Most pipe connections in espresso machines seal against a tapered metal-to-metal contact; nothing more is required. Be careful not to over-tighten when reconnecting...

    Mal.

  6. #6
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    A bit of graphite powder on the outer moving parts near the spring and lever pivot point might free it up too
    Dimal likes this.

  7. #7
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    Thanks for your advice. Took the plunge on the week-end and took out the pressurestat and descaled it. I thought scale would be white in colour. However, I could not believe the build up of black coloured material under the diaphragm. The diaphragm only had a slight white build up which rubbed off easily with a wet rag. I put the brass components in the descale solution and after a couple of hours the difference was amazing. I also took off the brass pipe and descaled the end that had scale build up. Re-assembled the pressurestat and it works great. The deadband is back to around 0.1 between the low and high points when the micro-switch turns off and on. I will in future include cleaning of the pressurestat as one of my maintenance jobs. Thanks again for your advice. Much appreciated. Graham
    Dimal likes this.



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