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Thread: Sight glass level ok cold... high when hot. Why?

  1. #1
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    Sight glass level ok cold... high when hot. Why?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Can anyone tell me what could cause a "normal" water level reading in a sight glass on a cold machine to increase above the max level and up over the top of the sight glass so that I can no longer see the meniscus under operating temperature....and then drop back to normal when cold again? It's driving me crazy.


    Thanks,
    Paolo

  2. #2
    Site Sponsor coffee_machinist's Avatar
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    most likely there's a blockage at one end that's only present when the parts have expanded from heat. This has happened with one of my Europiccoli, and it was the top flat surface of the glass butting up against the teflon seal that is under the sight glass plug, effectively blocking it from one end.

  3. #3
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    Hi CM,
    Thanks for replying.

    Does that mean that to get the sight glass to operate properly, I would have to dismantle and re-set the sight glass? Or is this something that might actually get better with use. I say this because (on this new machine) everything actually worked properly through one cold-hot-cold cycle properly yesterday...but played up several times today.

  4. #4
    Site Sponsor coffee_machinist's Avatar
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    What sort of machine is it? You *might* be able to wiggle the glass gently up or down by twisting when it's cold, but for peace of mind I'd be pulling it all apart and checking the seals. I'm guessing the machine doesn't auto-fill, so you really want to know where the water level is with confidence.

  5. #5
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    It does actually auto-fill...so I suppose as long as the water level is ok each time that I check it when cold, then all should be ok....still....a pain in the nether bits.

    Why would it have worked properly (once) yesterday?

  6. #6
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    a Londinium 1 ?

  7. #7
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    No...it's not a Londinium 1...

    The level in the sight glass has dropped on 2 separate occasions to the proper point when I operated the steam wand to froth milk. It will remain at the proper level until shutdown but start to rise again once the anti-vac valve shuts (and pressure in the boiler starts to build) on the next turn-on.

    I drained a couple of cups out of the hot water tap and the level dropped then accordingly too....and stayed there until heating up the next day.

    It is still driving me crazy!



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